Bosch Appliances Water Heater ESVVT User Manual

MODEL GWH 2700 ES NG and GWH 2700 ES LP -  
INDOOR MODEL  
Temperature Modulated with Electronic Ignition  
Suitable for heating potable water only  
Not approved for space heating purposes  
(Intended for variable flow applications)  
GWH 2700 ES NG - Natural Gas  
GWH 2700 ES LP - Liquefied Petroleum (LP) Gas  
Warning: If the information in this manual is not  
followed exactly, a fire or explosion may result  
causing property damage, personal injury or death.  
Do not store or use gasoline or other flammable  
vapor and liquids in the vicinity of this or any other  
appliance.  
What to do if you smell gas  
• Close gas valve. Open windows.  
• Do not try to light any appliance.  
• Do not touch any electrical switch; do not use any  
phone in your building.  
• If you cannot reach your gas supplier, call the fire  
department.  
Improper installation, adjustment, alteration,  
service or maintenance can cause injury or  
property damage. Refer to this manual. For  
assistance or additional information consult a  
qualified installer, service agency or the gas  
supplier.  
• Immediately call your gas supplier from a neighbor’s  
phone. Follow the gas supplier’s instructions  
• Installation and service must be performed by a  
qualified installer, service agency or the gas supplier.  
In the Commonwealth of Massachusetts this  
product must be installed by a licensed plumber or  
gas fitter.  
Upon completion of the installation, these  
instructions should be handed to the user of the  
appliance for future reference.  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Warning  
1
Warning  
Warning: The appliance should be  
located in an area where leakage of the  
heater or connections will not result in  
damage to the area adjacent to the  
appliance or to lower floors of the  
structure. When such locations cannot  
be avoided, it is recommended that a  
suitable drain pan, adequately drained,  
be installed under the appliance. The  
pan must not restrict combustion air  
flow.  
For your safety  
Do not store or use gasoline or other flammable,  
combustible or corrosive vapors and liquids in the  
vicinity of this or any other appliance.  
Warning: Carefully plan where you  
install the heater. Correct combustion  
air supply and flue pipe installation are  
very important. If a gas appliance is not  
installed correctly, fatal accidents can  
result, such as carbon monoxide  
poisoning or fire.  
Warning: The maximum inlet gas  
pressure must not exceed the value  
specified by the manufacturer and that  
the minimum value listed is for the  
purposes of input adjustment.  
Warning: Exhaust gas must be vented  
to outside using stainless steel vent  
material suitable for category III vent  
systems and temperatures up to 480°F.  
Vent piping must be sealed gas-tight to  
prevent possibility of flue gas spillage,  
carbon monoxide emissions and risk of  
fire, resulting in severe personal injury  
or death. Approved vent terminators  
must be used when penetrating to the  
outside.  
Warning: If a water heater is installed in  
a closed water supply system, such as  
one having a backflow preventer in the  
cold water supply line, means shall be  
provided to control thermal expansion.  
Contact the water supplier or local  
plumbing inspector on how to control  
this situation.  
Warning: Place the heater in a location  
where water leaks will do NO DAMAGE  
to adjacent areas or lower floors.  
Warning: Keeping appliance area clear  
and free from combustible materials,  
gasoline and other flammable vapors  
and liquids.  
Warning: Field wiring connections and  
electrical grounding must comply with  
local codes, or in the absence of local  
codes, with the latest edition of the  
National Electric Code, ANSI/NFPA 70,  
or in Canada, all electrical wiring must  
comply with the local codes and the  
Canadian Electrical Code, CSA C22.1  
Part 1.  
Warning: Do not obstruct the flow of  
combustion and ventilation air.  
Warning: Precautions must be taken  
prior to manually operating the relief  
valve to avoid contact with hot water  
coming out of the relief valve and to  
prevent water damage.  
Warning: Shock hazard: line voltage is  
present. Before servicing the water  
heater, unplug power supply cord from  
outlet. Failure to do so could result in  
severe personal injury or death.  
Caution: Label all wires prior to  
disconnection when servicing controls.  
Wiring errors can use improper and  
dangerous operation.  
Verify proper operation after servicing.  
Warning: The heater must be  
disconnected from the gas supply  
piping system during any pressure  
testing of that system at test pressures  
equal to or more than 0.5 psig.  
Warning: In order for the freeze  
prevention kit to provide adequate  
protection,120V AC must always be  
supplied to the water heater.  
3
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Appliance details  
2
Appliance details  
Warning: The anti freeze kit is  
designed to provide protection for the  
water heater down to approximately 5°F  
for short term conditions only. It will not  
protect the appliance in areas where the  
temperature is routinely expected to be  
below freezing.  
2.1 Features  
Parts  
• Key Pad interface control  
• High power pre-mix compact burner with low NOx  
emissions  
B The anti freeze kit will not protect  
plumbing outside the appliance from  
freezing. Precautions should be taken.  
• Modulating Gas Valve with constant gas:air ratio  
control  
B Always drain the water heater if it will be  
exposed to long term freezing  
conditions. See Section 6.2 Winterizing  
for seasonal use.  
• Modulating water valve for improved comfort and  
temperature control.  
High quality materials for long working life  
• Copper heat exchanger  
• High efficiency Ceramat Burner  
Warning: If a relief valve discharges  
periodically, this may be due to thermal  
expansion in a closed water supply  
system. Contact the water supplier or  
local plumbing inspector on how to  
correct this situation. Do not plug the  
relief valve.  
• Compact space saver: mounts on a wall with a  
supplied bracket.  
Features  
• Real-time diagnostics for troubleshooting/informational  
purposes  
• LCD Display with backlight  
• On/Off and Temperature control switches  
• Reset button  
FCC:  
This device complies with Part 15 of the FCC rules.  
Operation is subject to the following two conditions: (1)  
This device may not cause harmful interference, and (2)  
this device must accept any interference received,  
including interference that may cause undesired  
operation.  
• Program button (Selectable temperature default)  
• Failure codes for easy diagnostics and repair  
• Easily removable one-piece cover  
• Built in freeze prevention.  
Note: The freeze prevention is designed to provide  
protection for the water heater down to approximately 5°F  
for short term conditions only. It will not protect the  
appliance in areas where the temperature is routinely  
expected to be below freezing.  
D A N G E R  
- The freeze prevention will not protect plumbing outside  
the appliance from freezing. Precautions should be taken.  
Accessories (Bosch part #)  
• Optional wireless remote control accessory to operate  
with the appliance (TSTAT2)  
HOT  
• Cascading kit (TLINK)  
• Outdoor kit (AQOK)  
BURN  
• Gas conversion kit (8719002176)  
• Vertical vent kit (ESVVT)  
• Horizontal vent kit (AQ3ES1))  
Water temperature over 125°F can  
cause severe burns instantly or  
death from scalds.  
• Stainless steel bird screen (L2594)  
(fits into a 3” PCV fitting - Intake vent).  
Children, disabled and elderly are  
at highest risk of being scalded.  
BOSCH is constantly improving its  
products, therefore specifications are  
subject to change without prior notice.  
See instruction manual before  
setting temperature at water  
heater.  
i
Feel water before bathing or  
showering.  
1) AQ3 vent kit is compatible with this appliance but  
requires the purchase of an additional 12" piece of  
straight pipe to meet minimum vent length requirements.  
The aluminum flex piping included with this kit is not per-  
missible for use with this appliance.  
6720608643-16.1AL  
Fig. 1  
4
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Appliance details  
Dimensions  
2.2 Specifications (Technical data)  
Approved in US/Canada  
• Depth (in): 11¼” (286 mm)  
• Width (in): 17 7/8” (452 mm)  
• Height (in): 30½” (775 mm)  
• Weight: 67 pounds (30,5 kg).  
Capacity  
Maximum flow rate: 7.15 GPM (27 l/min) at a 45°F  
(25°C) rise.  
Gas types  
Maximum output  
Natural Gas.  
LP Gas.  
160,500 Btu/h (47.0 kW)  
Maximum input  
Converting the gas type can only be done by a certified  
gas technician with a calibrated CO2 analyzer.  
199,000 Btu/h (58.3 kW)  
Call Bosch Water Heating through Bosch  
thermotechnology corp. for conversion instructions.  
Efficiency in %  
Thermal efficiency > 82%  
Voltage  
Min. Input  
120 V AC (60 Hz) nominal  
19,900 Btu/h (5.8 kW)  
Amperage  
Temperature Control  
Idle - 40 mA  
Operation - 2.5 A  
Selection range: 100°F (38°C) - 140°F (60°C)  
Default temperature: 122°F (50°C)  
Stability: +/- 2°F (+/- 1°C)  
Noise  
45 - 65 db (A)  
Gas Requirement  
Safety devices  
Gas connection (inches) - ¾”  
• Flame failure device (ionization flame rod sensor)  
• Pressure relief valve (supplied with heater)  
• Over heat prevention (temperature limiter)  
• Inlet temperature sensor  
Inlet gas pressure under operation (with a high hot  
water flow rate)*  
• Propane: 8” - 13” water column  
• Natural Gas: 3.5” - 10.5” water column.  
• Outlet temperature sensor  
* To measure gas pressure, see Measuring Gas  
Pressure, chapter 3.12.  
• Backflow temperature sensor.  
Water protection  
Water  
IP X4 (protection against water drops)  
• Hot water connection (inches) - ¾”  
• Cold water connection (inches) - ¾”  
If appliance is installed at elevations above  
2000ft, refer to section 3.3.6 Fan speed  
adjustment.  
• Water valve material: Polymer (PPS) (Polypropylene  
Sulfid)  
i
• Minimum water flow: 0.65 gallon/minute (2,5 l/m).  
Note: Activation varies with inlet water temperatures  
from 0.65 - 1.6 gallon/minute.  
• Minimum recommended water pressure: 30 PSI  
(2.07 bar)  
Minimum recommended well pressure: 40 PSI (2.75  
bar), see chapter 3.9.  
• Connections:  
– Bottom of heater  
Combustion  
• NOx 40 Ng/J (Nanograms of NOx (calculated as NO ) per  
Joule of heat output).  
2
• CO 250 ppm (measured)  
• CO2 level set from factory, see chapter 6.4.  
5
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Appliance details  
To remove front cover  
2.3 Unpacking the heater  
B Loosen the two Philips head screws located on  
bottom rear of cover (see Fig. 3).  
Before installing the unit, be certain you have the  
correct heater for your type of Gas: Propane or  
Natural Gas. Identification labels are found on the  
shipping box, and on the rating plate which is located on  
the right side panel of the cover.  
Fig. 3 Loosen the two screws  
B Lift front cover panel upward and remove.  
Fig. 2 Rating plate  
A
B
Serial number  
Type of gas  
The box includes:  
• GWH 2700 ES  
• Pressure relief valve (150 psi / 200,000 Btu rating)  
• Bracket for wall hanging the heater  
• Exhaust vent adaptor (with 4 screws and gasket  
provided)  
• Combustion air inlet adaptor (with 3 screws and gas-  
ket provided)  
• Installation manual (manual can be downloaded at  
www.boschhotwater.com)  
• Product registration card  
• Energy Guide label.  
Fig. 4 Removing the front cover  
To remove combustion cover (service only)  
Please complete and return the enclosed product  
registration card.  
B Open the four clips and remove the combustion  
cover see Fig. 5.  
The GWH 2700 ES is not approved or designed  
for:  
• Manufactured (mobile) homes, boats or any mobile  
installation (modular homes are acceptable for  
installation)  
• Use above 8000 ft A.S.L. altitude (see page 18)  
• Outdoor installation without installation of Outdoor  
kit (AQOK)  
• Space heating purposes  
• Preheated inlet water supply.  
Fig. 5 Remove the combustion cover  
6
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Appliance details  
B
10. Failure to install heater correctly may lead to  
unsafe operation and void the warranty.  
2.4 General rules to follow for safe  
operation  
B
1. You must follow these instructions when you install  
your heater. In the United States: The installation must  
conform with local codes or, in the absence of local  
codes, the National Fuel Gas Code ANSI Z223.1/  
NFPA 54.  
In Canada: The Installation must conform with CGA  
B149.(1,2) INSTALLATION CODES and /or local  
installation codes.  
B 2. Carefully plan where you install the heater. Correct  
combustion air supply and vent pipe installation are  
very important. If not installed correctly, fatal  
accidents can occur, such as carbon monoxide  
poisoning or fire.  
B 3. When the unit is installed indoors and ROOM  
SEALED (twin pipe) it is permitted to be located in  
bathrooms, bedrooms and occupied rooms that are  
normally kept closed. See chapter 3.3 (page 9). If the  
unit will be installed indoors and use indoor  
combustion air, the place where you install the heater  
must have enough ventilation. The National Fuel  
Gas Code does not allow UNSEALED gas fired  
water heater installations in bathrooms,  
bedrooms or any occupied rooms normally  
kept closed. See chapter 3.5  
page 20).  
(page 21) and 3.4  
(
B 4. You must vent your heater. See chapter 3.3 on  
VENTING.  
B 5. The appliance and its gas connection must be leak  
tested before placing the appliance in operation.  
The appliance must be isolated from the gas supply  
piping system by closing its individual manual gas  
shutoff valve (not supplied with heater) during any  
pressure testing at pressures in excess of ½ Psig (3.5  
kPa).  
B 6. Keep water heater area clear and free from  
combustibles and flammable liquids. Do not locate  
the heater over any material which might burn.  
B 7. Correct gas pressure is critical for the proper  
operation of this heater. Gas piping must be sized to  
provide the required pressure at the maximum output  
of the heater, while all the other gas appliances are in  
operation. Check with your local gas supplier, and  
see the section on connecting the gas supply. See  
Section 3.8, page 17.  
B 8. Should overheating occur or the gas supply fail to  
shut off, turn off the gas supply at the manual gas shut  
off valve, on the gas line. Note: manual gas shutoff  
valve is not supplied with the heater but must be field  
installed.  
B 9. Do not use this appliance if any part has been  
underwater. Immediately call a qualified service  
technician to inspect the appliance and to replace any  
part of the control system and any gas control which  
has been underwater.  
7
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Appliance details  
2.5 Dimensions and Minimum installation clearances  
16  
41 " 5 ¼"  
6 ½"  
21 16"  
11 ¼"  
5 ¼"  
7
17  
8
"
1
2
5
6
+
reset  
P
7
3
4
6720608158-04.2AL  
Fig. 6 Dimensions  
1
2
3
4
5
6
7
On/Off button  
Reset button  
Program key  
Model GWH 2700 ES  
TOP (A)  
12”  
1”  
Power ON or stand-by LED  
LCD display  
Up button  
FRONT (B)  
BACK  
Down button  
0”  
SIDES  
1”  
FLOOR (C)  
12”  
Table 1 Minimum clearances  
Fig. 7 Minimum clearances  
Note: For servicing access, a 2ft clearance to front  
cover is recommended.  
8
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3
Installation instructions  
3.1 Tools required for installation  
Warning: Approved terminators must  
be used for inlet and exhaust vent sys-  
tems to prevent rain from entering the  
appliance. Failure to do so may result in  
damage to the appliance. This failure is  
not covered under the manufacturer’s  
warranty.  
• Philips head screwdriver  
• Flat head screwdriver  
• Adjustable wrench  
• Level  
• Thermometer  
• Standard plumbing tools  
• Manometer  
Caution: The vent system must be  
installed by a qualified installer in  
accordance with these instructions. If  
• Drill  
improperly installed,  
a
hazardous  
• Pipe wrench  
condition such as explosion or carbon  
monoxide poisoning could result.  
Bosch Water Heating will not be  
responsible for improperly installed  
appliances.  
• Adjustable pliers  
• Pipe fitting tools  
• Hacksaw  
• Hole saw.  
Warning: In areas where outside  
temperatures routinely come close to  
freezing, sealed combustion operation  
is required. Use separate terminations  
for combustion and vent, which must be  
installed on the same wall or roof  
surface, however never facing the  
direction of prevailing winds. Failure to  
do so may result in heat exchanger  
freezing up and bursting. This failure is  
not covered under the manufacturer's  
warranty.  
3.2 Introduction  
Please follow these instructions. Failure to follow  
instructions may result in:  
B Damage or injury.  
B Improper operation.  
B Loss of warranty.  
If you are unable to perform the tasks required to install  
this heater properly, please contact a locally licensed  
plumber or gas technician.  
Common installation practice is to deter-  
mine the venting/intake system layout and  
penetration and then work back to the  
heater.  
3.3.1 Vent material  
i
Establish vent clearances that comply with the vent  
manufacturer's specifications. In all cases, follow local  
codes. See Table 2.  
3.3 Venting  
Diam.  
Material  
Warning: Do not reduce the vent  
(exhaust and combustion) pipe sizes  
and do not common vent with any other  
vented appliance or stove.  
Exhaust  
Vent  
3 or 4 inches Sealed single wall stainless steel  
(AL29-4C)  
Intake  
Vent  
3 or 4 inches Sealed PVC or any other rigid pipe  
Warning: Failure to vent the exhaust  
gases to the outside with sealed  
stainless steel vent pipe (AL29-4C)  
may result in dangerous flue gases  
filling the structure in which it is  
installed.  
Table 2 Venting Specifications  
Warning: Do not mix vent pipe or  
from  
joining methods  
manufacturers.  
different  
9
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Horizontal venting systems only:  
3.3.2 Venting Specifications  
An optional stainless concentric vent/air intake termina-  
tion can be used to provide only one penetration point  
through the exterior wall (see Fig. 8, 9 & 10). The con-  
centric vent/air intake kit can be ordered from your local  
wholesaler. (Part# ESHCK). Note: Vent piping and  
terminal used with concentric vent/air intake kit  
must be from the same vent pipe manufacturer.  
The appliance can also be installed with separate  
air intake and exhaust piping (see Fig. 15 ).  
Install appliance as close to point of vent termination as  
possible. The exhaust piping must vent directly to the  
outside of the structure.  
Horizontal sections of vent must pitch upward towards  
termination ¼" for every foot of horizontal length, to  
prevent the pooling of condensate, and be supported at  
4 foot intervals with overhead hangers.  
Exception: horizontal run between last elbow and  
termination must pitch down to termination 1/4" per  
foot. Note: For horizontal terminations, venting must  
terminate once it penetrates to the outside of the  
structure. There must be no sections of vent pipe  
exposed to the outdoors other than the termination.  
Note: Listed thimbles or collars are necessary where  
venting passes through wall and ceiling partitions. If the  
vent system passes through combustible areas where  
the vent clearance requirements cannot be maintained,  
it is permissible to chase straight sections of sea led 3  
inch single wall vent through 4 inch (or greater) T ype-B  
vent. The distance to combustibles using this chase  
technique is 1 inch 1). Note: Type-B vent must never be  
used as the actual exhaust vent system for the  
appliance, as it is not gas tight and illegal for use with  
this appliance. This will create a serious health hazard  
and void the warranty.  
6720608782-09.1Av  
Fig. 8 Concentric kit part # ESHCK  
3”  
VENTING  
Z flex  
Protech  
Heat Fab  
3 or 4"  
90° elbow  
2SVEEWCF0390  
FSELB9003  
9314  
3”  
Horizontal  
Terminal  
2SVSTB03  
FSTB3  
FSRC3  
9390 TEE  
5300CI  
6720608782-10.1Av  
3” Vertical  
Terminal  
2SVSRCF03  
Fig. 9 Concentric kit vent assembly  
Table 3 Terminator Part Numbers  
Fittings or Piping  
Equivalent  
feet  
m
12"  
45 degree elbow  
90 degree elbow  
pipe per foot  
1.25  
2.5  
1
0.38  
0.76  
0.30  
Min. 3 Feet  
3” stainless steel pipe  
Table 4 Friction Loss Equivalent in piping and fittings  
For specific questions concerning vent material, speci-  
fications, usage or installation, please contact the vent  
manufacturer directly.  
Company  
Z-flex  
Contact info  
800-654-5600  
ProTech Industries  
Heat-Fab  
800-766-3473  
800-772-0739  
6720608782-11.1Av  
Fig. 10 Concentric kit installation  
Table 5 Vent manufacturers  
10  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
# of 90° elbows  
Condensate drain requirements  
Air intake or  
Exhaust  
system  
An external condensate drain (not supplied with the  
heater) must be installed under the following  
conditions:  
0
1
2
3
4
0
1
2
N/A*  
N/A*  
23  
26  
23  
20  
17  
14  
11  
8
21  
18  
15  
12  
9
16  
13  
10  
7
11  
8
• All vertical terminating vent installations.  
• Horizontal terminating vent installations where the  
total linear vent length is greater than 10 feet (3.1 m).  
5
• Vent installations where any section of the exhaust  
vent pipe passes through an unconditionedspace.  
# of 45°  
3
20  
N/A**  
N/A**  
elbows  
4
5
6
17  
4
Twin pipe termination clearances  
The minimum clearance between exhaust vent and  
combustion air inlet terminations for twin pipe  
penetration is 3 feet.  
14  
6
N/A** N/A**  
N/A** N/A**  
11  
3
Maximum allowable straight pipe length (ft)  
Minimum combustion air and exhaust pipe  
length  
Table 6 Maximum allowable straight pipe length  
The minimum exhaust pipe length is 3 feet (1m) of  
straight vent pipe. The minimum combustion air pipe  
length is one 90° elbow.  
*
Not allowed. At least one 90º elbow required.  
Not allowed. Minimum of 3 feet (1m) of straight pipe required.  
**  
Maximum combustion air and exhaust pipe  
length  
The following table (Table 6) displays the maximum  
allowable straight pipe lengths for combustion air and  
exhaust piping with consideration to the number of  
elbows used.  
Note: 90° elbows used for terminations  
should not be counted in the exhaust and  
combustion air piping.  
i
Step 1: Total the number of 90° elbows and 45°  
elbows used on the exhaust piping.  
Step 2: Use this value in the table to determine the  
maximum straight exhaust pipe length  
allowed.  
Step 3: Total the number of 90° elbows and 45°  
elbows used on the combustion air piping.  
Step 4: Use this value in the table to determine the  
maximum straight combustion air pipe length  
allowed.  
11  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Required direct vent terminal clearances (twin pipe / concentric penetration)  
6720608836-23.1Av  
Fig. 11  
1)  
2)  
Canadian installations  
U.S. installations  
A
B
C
D
Clearance above grade, veranda, porch, deck or balcony  
Clearance to window or door that may be opened  
Clearance to permanently closed window  
12 in.  
12 in.  
36 in.  
12 in.  
*
*
*
*
Vertical clearance to ventilated soffit located above the vent  
terminator within a horizontal distance of 2 feet (61cm) from the  
center line of the terminator  
E
F
Clearance to unventilated soffit  
Clearance to outside corner  
Clearance to inside corner  
*
*
*
*
*
*
*
G
H
Clearance to each side of center line extended above meter/  
regulator assembly  
36 in. within a height 15 feet above  
meter/ regulator assembly  
I
Clearance to service regulator vent outlet  
36 in.  
36 in.  
*
J
Clearance to non-mechanical air supply inlet to building or the  
combustion air inlet to any other application  
12 in.  
K
L
Clearance to mechanical air supply inlet  
72 in.  
36 in. above if within 10 feet  
horizontally  
Clearance above paved sidewalk or paved driveway located on  
public property  
84 in. 3)  
12 in. 4)  
*
*
M
Clearance under veranda, porch deck or balcony  
Table 7  
1)  
2)  
In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code  
In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code  
3)  
4)  
A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.  
Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor.  
*
For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA-B149.1, one of the following shall be indicated:  
a) A minimum clearance value determined by testing in accordance with section 2.20, or;  
b) A reference to the following footnote:  
“Clearance in accordance with local installation codes and the requirements of the gas supplier.”  
12  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Required other than direct vent terminal clearances (single pipe penetration)  
6720608836-23.1Av  
Fig. 12  
1)  
2)  
Canadian installations  
U.S. installations  
A
B
Clearance above grade, veranda, porch, deck or balcony  
Clearance to window or door that may be opened  
12 in.  
36 in.  
12 in.  
4 feet below or to side of opening;  
1 foot above opening  
C
D
Clearance to permanently closed window  
*
*
*
*
Vertical clearance to ventilated soffit located above the vent  
terminator within a horizontal distance of 2 feet (61cm) from the  
center line of the terminator  
E
F
Clearance to unventilated soffit  
Clearance to outside corner  
Clearance to inside corner  
*
*
*
*
*
*
*
G
H
Clearance to each side of center line extended above meter/  
regulator assembly  
36 in. within a height 15 feet above  
meter/ regulator assembly  
I
Clearance to service regulator vent outlet  
36 in.  
36 in.  
*
J
Clearance to non-mechanical air supply inlet to building or the  
combustion air inlet to any other application  
4 feet below or to side of opening;  
1 foot above opening  
K
L
Clearance to mechanical air supply inlet  
72 in.  
36 in. above if within 10 feet  
horizontally  
Clearance above paved sidewalk or paved driveway located on  
public property  
84 in. 3)  
12 in. 4)  
84 in.  
*
M
Clearance under veranda, porch deck or balcony  
Table 8  
1)  
2)  
In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code  
In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code  
3)  
4)  
A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.  
Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor.  
*
For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA-B149.1, one of the following shall be indicated:  
a) A minimum clearance value determined by testing in accordance with section 2.20, or;  
b) A reference to the following footnote:  
“Clearance in accordance with local installation codes and the requirements of the gas supplier.”  
13  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3.3.3 Venting configuration examples  
Below are approved examples of horizontal  
venting installations.  
4"  
HORIZONTAL RUN  
1/4" PER FOOT  
DOWN TO  
TERMINATOR.  
CONDENSATE  
DRAIN  
6720608542-05.2AL  
Fig. 15 Horizontal twin pipe penetration  
6720608542-02.2AL  
Below are approved examples of vertical venting  
installations.  
Fig. 13 Horizontal side wall venting installation (single  
pipe penetration)*  
Important:  
* Warning: for non-freezing climates only!  
Note: Pitch horizontal runs down toward the heater,  
1/4" per foot.  
Important:  
Note: Pitch horizontal runs down toward the heater,  
except horizontal run between last elbow and termina-  
tion which must slope down to termination 1/4" per  
foot.  
RAIN CAP  
10' MIN.  
2' MIN.  
STORM COLLAR  
3' MIN.  
FLASHING  
Note: For horizontal terminations, venting must  
terminate once it penetrates to the outside of the  
structure. There must be no sections of vent pipe  
exposed to the outdoors.  
FIRESTOP SUPPORT  
4" MIN.  
AIR SPACE  
FIRESTOP SUPPORT  
12"  
HOSE  
CLAMP  
Min. 3 Feet  
3” stainless steel pipe  
ELBOW  
CONDENSATE  
DRAIN  
APPLIANCE  
6720608158-91.2Av  
Fig. 16 Vertical venting installation (single pipe pene-  
tration)*  
6720608782-11.1Av  
Fig. 14 Horizontal venting installation (concentric  
penetration)  
* Warning: for non-freezing climates only!  
14  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3.3.4 Vent connections  
B Attach the flue gas exhaust accessory (8 705 504  
162) to the top of the unit (position 1) using the 4  
screws and gasket provided. Fully insert stainless  
steel vent pipe 1.5” minimum into the accessory and  
tighten the clamp (position 2).  
NOTE: Vent pipe must be completely ver-  
tical when inserting or gasket inside ex-  
haust accessory can become displaced.  
Exhaust accessory can be removed with  
vent pipe attached to check gasket posi-  
tion.  
i
Fig. 17 Vertical venting installation (twin pipe penetra-  
tion)  
RAIN CAP  
10' MIN.  
STORM COLLAR  
FLASHING  
2' MIN.  
SILICONE SEAL  
3' MIN.  
Fig. 19  
B Attach the combustion air inlet accessory (8 705  
504 116) to the top of the unit (position 3) using the  
3 screws and gasket provided, and install air intake  
pipe over the accessory. NOTE: The appliance has  
the option to mount the combustion air inlet acces-  
sory on the top right or on the top left side of the  
heater. The combustion air inlet that is not used must  
be kept sealed.  
CHIMNEY  
MAY BE INSULATED  
IF NECESSARY  
HORIZONTAL RUN  
1/4" RISE/FT  
HANGER STRAP  
MORTAR  
ELBOW  
ELBOW  
HOSE  
CLAMP  
CONDENSATE  
DRAIN  
Fig. 20  
B Ensure that exhaust vent pipe is fully inserted in collar  
to enable proper connection.  
APPLIANCE  
Exhaust venting must be 3" or 4" sealed  
single wall stainless steel (AL29-4C) vent  
pipe.  
6720608158-14.2AL  
Fig. 18 Vertical venting installation - Masonry Chim-  
ney (combustion air piping not shown)  
i
15  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3.3.5 Condensate drain installation  
Note: Do not install condensate drain in areas where it  
may freeze.  
1. Install condensate drain as close to heater as possi-  
ble.  
2. Use 3/8" ID high temperature silicone tube to con-  
nect to condensate drain port. Do not use copper pip-  
ing for any portion of the condensate drain.  
3. Form a condensate trap by means of a 3" loop par-  
tially filled with water.  
4. To increase the tube length, connect to end of the  
high temperature silicone tubing with vinyl tubing, PVC  
or CPVC pipe. Do not reduce the internal diameter at  
any point.  
5. Dispose of condensate according to local codes.  
RAIN CAP  
10' MIN.  
2' MIN.  
STORM COLLAR  
3' MIN.  
FLASHING  
FIRESTOP SUPPORT  
4" MIN.  
AIR SPACE  
ELBOW  
CONDENSATE  
DRAIN TEE  
DRAIN TRAP  
TO DRAIN - DISPOSE  
OF CONDENSATE  
ACCORDING TO  
LOCAL CODES  
APPLIANCE  
6720608782-04.2Av  
Fig. 21 Condensate drain installation (combustion air  
piping not shown)  
3" Venting  
Z-flex  
ProTech Heat Fab  
90°  
Condensate  
Drain Tee  
2SVEVWCF03 FST3 &  
FSDF3  
93PPLSTEE  
Horizontal  
Condensate  
Drain  
2SVEDWCF03 FSHDT3  
9321  
Condensate  
Drain Tube  
2SVEDTK24  
N/A  
7000TUBE  
Table 9 Approved Condensate Drain Part Numbers  
16  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3.3.6 Fan speed adjustment  
Example  
Exhaust  
IMPORTANT! Installation adjustment:  
• 7 - 3' straight sections  
After installing the water heater, the fan speed values for  
minimum power (P2) and maximum power (P1) may  
need adjustment due to variations in altitude and vent  
pipe length.  
• 1 - 1' straight section = Total straight pipe length 22’  
• 2 - 90° elbow.  
Intake  
Failure to make necessary adjustments to fan speed  
values may result in improper operation of the  
appliance.  
• 5 - 3' straight sections = Total straight pipe length 15’  
• 1 - 90° elbows.  
First calculate the total equivalent vent length. Use this  
value to determine the appropriate fan speed values,  
found in Table 12 and make any necessary  
adjustments. After changing fan speed values proceed  
to Section 6.4 to confirm CO2 values are within  
specified ranges.  
Example  
Exhaust  
Straight section length  
(feet)  
22 x 1 =  
22  
Total equivalent vent length calculation  
90° elbows (qty)  
45° elbows (qty)  
Total:  
1 x 2.5 =  
2.5  
0
B Determine the total length of all straight sections of  
vent pipe and enter in table 10, line 1.  
0 x 1.25 =  
B Count the number of 90° elbows used and enter that  
value in line 2. (Do not count terminals and first elbow  
used on intake and exhaust).  
24.5  
B Count the number of 45° elbows used and enter that  
value in line 3.  
Intake  
B Repeat steps 1 through 3 for air intake pipe and enter  
those values in the intake section of table 10.  
Straight section length  
(feet)  
15 x 1 =  
15  
B Add line 4 from Exhaust to line 4 of Intake and enter  
result in line 5.  
This is the total equivalent vent length.  
90° elbows (qty)  
45° elbows (qty)  
Total:  
1 x 2.5 =  
0
0 x 1.25 =  
0
Exhaust  
15  
39.5  
1
2
3
4
Straight section length  
(feet)  
__ x 1 = ____  
__ x 2.5 = ____  
__ x 1.25 = ____  
Total equivalent vent length =  
Table 11 Determining vent length combination exam-  
ple  
90° elbows (qty)  
Note: Do not count terminals and first elbow used on  
intake and exhaust.  
45° elbows (qty)  
Total:  
____  
Total equivalent length must not to  
exceed 57ft.  
i
Intake  
1
2
3
4
5
Straight section length  
90° elbows (qty)  
__ x 1 = ____  
__ x 2.5 = ____  
__ x 1.25 = ____  
Total: ____  
NOTE: If using concentric terminal include  
exhaust pipe length that is part of the con-  
centric terminal.  
i
45° elbows (qty)  
Total equivalent vent length = ____  
Table 10 Determining vent length combination (see  
example in Table 11)  
17  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Natural Gas  
Maximum  
power fan power fan speed power fan speed  
Liquid propane  
Maximum  
Altitude  
(above sea  
level)  
Total  
equivalent  
vent length1)  
Minimum  
speed (P2)  
(P1)  
(P1)  
5.5 - 32 ft  
33 - 57 ft  
5.5 - 32 ft  
33 - 57 ft  
5.5 - 32 ft  
33 - 57 ft  
7
8
0 - 2000 ft  
(0 - 610 m)  
No  
modification required  
No  
modification required  
For operation at elevations  
above 2,000 ft (610 m) the  
equipment ratings shall be  
reduced at the rate of 4% for  
each 1,000 ft (305 m) above sea  
level  
8*  
8*  
9*  
9*  
48*  
49*  
49*  
50*  
47*  
48*  
48*  
49*  
2000 - 4500 ft  
(610 - 1372 m)  
4500 - 8000 ft  
(1372 - 2439 m)  
* Above 2000 ft, CO2 levels must be checked with a combustion gas analyzer, see section 6.4 for instructions.  
Table 12 Fan speed adjustment  
1)  
Full equivalent length (inlet + outlet piping + fittings)  
Adjusting minimum power fan speed (P2)  
Adjusting maximum power fan speed (P1)  
To select fan speed:  
To select fan speed:  
B Press ON/OFF button into OFF.  
B Press ON/OFF button into OFF.  
B Press and hold "Program" button  
ON/OFF button to turn appliance ON.  
and press  
B Press and hold "Program" button  
ON/OFF button to turn appliance ON.  
and press  
Fig. 22  
Fig. 23  
B As soon as '188' is displayed, release "Program"  
button  
B As soon as '188' is displayed, release "Program" but-  
ton  
, and the display should read P2.  
, and the display reads P2.  
B Press  
or to choose the fan speed suitable  
B Press the minus button  
B Press “Program” button  
The current setting will appear on the display.  
to display P1.  
with your installation, see Table 12.  
to enter P1 adjustment.  
B Press and hold ( 5 sec.) “Program” button  
until  
the display flashes, then the selected value is memo-  
rized.  
B Press or to choose the fan speed suitable  
with your installation, see Table 12.  
B Press and hold ( 5 sec.) “Program” button  
until  
Do not set P2 to greater then 9.  
the display flashes, then the selected value is memo-  
rized.  
i
Proceed directly to Section 6.4 to confirm  
CO2 values are within range.  
i
18  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Attention residents of the Commonwealth of  
Massachusetts:  
signage installed in accordance with the provisions of  
248 CMR 5.08(2)(a)1 through 4.  
In the Commonwealth of Massachusetts the following  
regulation went into effect on 12/30/2005:  
(b) EXEMPTIONS: The following equipment is exempt  
from 248 CMR 5.08(2)(a)1 through 4:  
(a) For all side wall horizontally vented gas fueled  
equipment installed in every dwelling, building or  
structure used in whole or in part for residential  
purposes, including those owned or operated by the  
Commonwealth and where the side wall exhaust vent  
termination is less than seven (7) feet above finished  
grade in the area of the venting, including but not limited  
to decks and porches, the following requirements shall  
be satisfied:  
1. The equipment listed in Chapter 10 entitled  
"Equipment Not Required To Be Vented" in the most  
current edition of NFPA 54 as adopted by the Board;  
and  
2. Product approved side wall horizontally vented gas  
fueled equipment installed in a room or structure  
separate from the dwelling, building or structure used in  
whole or in part for residential purposes.  
(c) MANUFACTURERS REQUIREMENTS - GAS  
EQUIPMENT VENTING SYSTEM REQUIRED. When  
the manufacturer of Product Approved side wall  
horizontally mounted gas equipment provides a venting  
system design or venting system components with the  
equipment, the instructions provided by the  
manufacturer for the installation of the equipment and  
the venting shall include:  
1. INSTALLATION OF CARBON MONOXIDE  
DETECTORS. At the time of installation of the side wall  
horizontal vented gas fueled equipment, the installing  
plumber or gasfitter shall observe that a hard wired  
carbon monoxide detector with an alarm and battery  
back-up is installed on the floor level where the gas  
equipment is to be installed. In addition, the installing  
plumber or gasfitter shall observe that a battery  
operated or hard wired carbon monoxide detector with  
an alarm is installed on each additional level of the  
dwelling, building or structure served by the side wall  
horizontal vented gas fueled equipment. It shall be the  
responsibility of the property owner to secure the  
services of qualified licensed professionals for the  
installation of hard wired carbon monoxide detectors.  
1. Detailed instructions for the installation of the venting  
system or the venting system components: and  
2. A complete parts list for the venting system design or  
venting system.  
(d)MANUFACTURER REQUIREMENTS  
-
GAS  
EQUIPMENT VENTING SYSTEM NOT PROVIDED.  
When the manufacturer of a product approved side wall  
horizontally vented gas fueled equipment does not  
provide the parts for the venting of flue gases, but  
identifies "special venting systems," the following  
requirements shall be satisfied by the manufacturer:  
a. In the event that the side wall horizontally vented gas  
fueled equipment is installed in a crawl space or an at  
tic, the hard wired carbon monoxide detector with alarm  
and battery back-up may be installed on the next  
adjacent floor level.  
1. The referenced "special venting system" instructions  
shall be included with the appliance or equipment  
installation instructions; and  
b. In the event that the requirements of this subdivision  
can not be met at the time of completion of installation,  
the owner shall have a period of thirty (30) days to  
comply with the above requirements; provided,  
however, that during said thirty (30) day period, a  
battery operated carbon monoxide detector with an  
alarm shall be installed.  
2. The "special venting systems" shall be product  
approved by the Board, and the instructions for that  
system shall include a parts list and detailed installation  
instructions.  
(e) A copy of all installation instructions for all products  
approved side wall horizontally vented gas fueled  
equipment, all venting instructions, all parts lists for  
venting instructions, and/or all venting design  
instructions shall remain with the appliance or  
equipment at the completion of the installation.  
2. APPROVED CARBON MONOXIDE DETECTORS.  
Each carbon monoxide detector as required in  
accordance with the above provisions shall comply with  
NFPA 720 and be ANSI/UL 2034 listed and IAS  
certified.  
3. SIGNAGE. A metal or plastic identification plate shall  
be permanently mounted to the exterior of the building  
at a minimum height of eight (8) feet above grade  
directly in line with the exhaust vent terminal for the  
horizontally vented gas fueled heating appliance or  
equipment. The sign shall read, in print size no less than  
one half (1/2) inch in size, "GAS VENT DIRECTLY  
BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS".  
4. INSPECTION. The state or local gas inspector of the  
side wall horizontally vented gas fueled equipment shall  
not approve the installation unless, upon inspection, the  
inspector observes carbon monoxide detectors and  
19  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
below for providing adequate combustion air for the  
water heater as well as any other appliances that may  
consume air in the space. Always follow local codes if  
they are more stringent.  
3.4 Combustion air requirements  
Warning: In areas where outside  
temperatures routinely come close to  
freezing, sealed combustion operation  
is required. Use twin pipe or concentric  
terminations for combustion air and  
exhaust, which must be installed on the  
same wall or roof surface, however  
never facing the direction of prevailing  
winds. Failure to do so may result in  
heat exchanger freezing up and  
bursting. This failure is not covered  
under the manufacturer's warranty.  
When all requirements are followed, the unit will  
operate properly and safely. However, there may still be  
a risk of freezing due to negative draft if the other  
combustion appliances in the building are not supplied  
with sufficient combustion air. A wood stove or furnace  
can pull its combustion air from the heater's vent pipe,  
allowing the cold incoming air to freeze the cold water  
in the heat exchanger. Supplying more combustion air  
for all combustion appliances is the solution. A HVAC  
specialist should be consulted to design solutions for  
providing more combustion air. Observe the following  
guidelines:  
Installations in structures that have been tightly  
constructed (air infiltration rate of 0.40 ACH or less)  
must be provided with combustion air per the National  
Fuel Gas Code. Consult a HVAC specialist if your air  
infiltration rate is questionable.  
Warning: When installed in an  
environment where corrosive chemicals  
or dirty air (e.g. hair salons, car washes)  
are present the twin pipe system is  
required.  
The space must have two permanent openings, one  
commencing within 12 inches of the top and one  
commencing within 12 inches of the bottom of the  
enclosure.  
Twin pipe and Concentric pipe  
The water heater is designed as a sealed combustion  
appliance. It is recommended that the combustion air  
be provided from the outside by a dedicated pipe (twin  
pipe) or by connecting to the concentric vent kit (see  
Fig. 8, 9 & 10). The combustion air pipe may be PVC  
or any other rigid sealed 3" or 4" pipe. Horizontal  
sections of the combustion air pipe must pitch down  
towards termination 1/4" per foot to prevent rain water  
from entering the appliance. When using the twin pipe  
method, combustion air inlet, whether terminating  
vertically or horizontally, must be located in such a  
manner as to provide a minimum 3 foot clearance  
from the exhaust vent terminator. See Fig. 11 and  
Fig. 12 Letter I, page 12.  
Each opening must have a minimum free area of one  
square inch per:  
• 1000 Btu/hr if all air is taken from inside the building  
• 2000 Btu/hr if all air is taken from the outside by  
horizontal ducts  
• 4000 Btu/hr if all air is taken from the outside by  
direct openings or vertical ducts.  
Or the space must be provided with one permanent  
opening or duct that is within 12 inches of the ceiling of  
the enclosure.  
For the maximum length of the combustion air  
inlet pipe, see table 6.  
This opening must have a minimum free area of one  
square inch per:  
• 3000 Btu/hr if all air is taken from the outside by a  
direct opening or vertical duct.  
Warning: Vent terminations must  
prevent rain from entering the  
combustion air and exhaust vent piping.  
Louvers, grills and screens have a blocking effect. If the  
effective free area is not known, increase the sizes of  
your openings by 300% if your louvers are wood and by  
43% if your louvers are metal. Refer to the National Fuel  
Gas Code for complete information.  
Single pipe  
Note: This appliance requires 9950 cubic feet of  
available combustion air, or a minimum of 1243  
square feet of space with an 8 foot ceiling to  
operate. If the large amount of air space, which  
equates to about half of most average sized  
homes, is not available, the appliance must pull  
air from outside (see twin pipe system above).  
Although it is permissible to draw combustion air from  
inside the structure, it is not the manufacturer’s  
recommended installation method. Always install a 3  
inch elbow on the top of the combustion air inlet  
adaptor to prevent foreign objects from falling into the  
unit.  
If a single pipe installation is utilized, follow guidelines  
20  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3.5 Proper location for installing your  
heater  
3.7 Mounting installation  
Warning: before starting  
installation  
Carefully select the location of the water heater. For  
your safety and for proper heater operation, you must  
provide combustion air to the heater and a proper  
exhaust vent system.  
B Check that there are no loose or  
the  
damaged  
appliance  
parts  
inside  
Follow the guidelines below:  
B Confirm the gas type of the heater  
matches the gas supply you will be  
connecting the heater, see Fig. 2,  
page 6.  
B 1. Locate the heater where venting, gas and  
plumbing connections are feasible and convenient.  
B 2. The hot water lines should be kept short and  
insulated to save energy. Centrally locating the water  
heater is recommended to keep hot water  
distribution times even throughout the structure.  
Front cover should be removed (see  
instructions on page 6) in order to inspect  
components visually.  
i
Warning: The water in this water  
heater is cold and always remains cold  
except for the times the burner is on. In  
the event of power outage in  
conjunction with freezing temperatures,  
it is recommended that the heater be  
drained.  
Warning: Do not install this appliance  
on a carpeted wall. The heater must be  
mounted on a wall using appropriate  
anchoring materials.  
See chapter 6.2, page 32 “Winterizing”  
for draining instructions.  
Warning: In areas where outside  
temperature is routinely below 32°F and  
the heater is to be installed on the inside  
of an exterior wall, a minimum 2" air gap  
or rigid insulation between the heater  
back and the wall is recommended.  
Warning:  
Flammable  
materials,  
gasoline, pressurized containers, or any  
other items or articles that are potential  
fire hazards must NOT be placed on or  
adjacent to the heater. The appliance  
area must be kept free of all  
combustible materials, gasoline and  
other flammable vapors and liquids.  
If wall is sheathed with plaster or drywall, it is recom-  
mended that two support boards, either 1”x4” or 1/2"  
(minimum) plywood first be attached across a pair of  
studs, see Fig. 24.  
B Secure the wall mounting bracket provided with the  
heater to the wall surface. The heater must be kept  
level on the wall surface (see Fig. 25).  
3.6 Heater placement and clearances  
The water heater is approved for installation on a  
combustible wall (see chapter 3.7 Mounting  
installation) provided the floor covering below  
the heater is noncombustible. For installations in an  
alcove or closet, maintain the minimum clearances to  
combustible and non-combustible materials. See Fig. 7  
and Table 1 on page 8.  
B Hang the appliance on the bracket, see Fig. 26.  
Clearances from any exhaust vent pipe are dependent  
upon the clearance requirements of the stainless steel  
vent pipe manufacturer. Single wall stainless steel  
(AL29-4C) vent pipe (vent type rated for Category III  
appliances) must be used when exhaust venting this  
appliance. See chapter 3.3 (page 9) Venting.  
Studs 16"  
(406mm) on  
center  
Fig. 24 Distance between support boards  
21  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
3.8 Gas piping & connections  
Before connecting the gas supply, check the rating  
plate on the right side of the heater to be sure that the  
heater is rated for the same gas to which it will be  
connected.  
In the United States: The installation must conform with  
local codes or, in the absence of local codes, the  
National Fuel Gas Code ANSI Z223.1/NFPA 54.  
In Canada: The Installation must conform to CSA B149  
INSTALLATION CODES and/or local installation  
codes.  
Warning: DO NOT connect to an  
unregulated or high pressure propane  
line or to a high pressure commercial  
natural gas line.  
6720608158-64.1AL  
Warning: The heater must be isolated  
from the gas supply piping system  
during any pressure testing of that  
system at test pressures equal to or  
more than 0.5 psig. If overpressure has  
occurred, such as through improper  
testing of the gas lines or malfunction of  
the supply system, the gas valve must  
be checked for safe operation.  
Fig. 25 Leveling the mounting bracket on the studs  
GAS CONNECTIONS  
B Install a manual gas shut off valve on the gas supply  
line within easy reach of the appliance.  
B Install a union when connecting gas supply.  
B The minimum internal diameter required for  
any appliance connector is ¾”.  
B Undersized flexible appliance connectors not  
permitted.  
B National Fuel Gas Code requires that a sediment  
trap (drip leg) be installed on gas appliances not so  
equipped. The drip leg must be accessible and not  
subject to freezing conditions. Install in accordance  
with the recommendations of the serving gas sup-  
plier, see Fig. 27.  
6720608158-05.1AL  
Fig. 26 Mounting the heater  
Warning: Appliance must be installed  
vertically.  
Gas supply  
Minimum  
3”  
Cap  
Fig. 27 Gas connection (drip leg)  
22  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Once connections are made, check for gas leaks at all  
joints. Apply some gas leak detection solution to all gas  
fittings. Bubbles are a sign of a leak. A combustible gas  
detector may also be used to detect for leaks.  
Danger: If you have a leak, shut off the  
gas. Tighten appropriate fittings to stop  
leak. Turn the gas on and check again  
with a gas leak detection solution.  
Never test for gas leaks using a match  
or flame.  
GAS LINE SIZING  
The gas supply piping for a single heater should be  
sized for a maximum draw of 199,000 BTUH. Measure  
the length of gas supply line and use the tables in  
Fig. 29, page 24 or the gas line manufacturer’s sizing  
tables to determine the pipe diameter necessary to  
accommodate the 199,000 BTU demand of the heater.  
If there are more gas appliances on the line, size the gas  
line according to the total maximum amount of BTU  
input rating for all appliances.  
Note: Undersizing the gas line may result in diminished  
hot water flow rate and temperature. See chapter 3.12,  
page 27 for the procedure to confirm gas pressure.  
Proper gas pressure must be confirmed at time of  
installation.  
Inlet gas particle screen  
(included)  
Gas piping  
Fig. 28  
23  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
FOR NATURAL GAS  
Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop  
of 0.3” in Water Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands.  
Follow boxed numbers for piping just one GWH 2700 ES (example: ¾” B.I. Natural Gas pipe for 10 ft (3.0m).  
will handle 278,000 btu’s (81.5 kWh). For multiple appliances combine the total maximum btu input load and  
then refer to applicable chart below.  
Nominal  
Iron  
Length of Black iron Pipe , Feet  
Pipe  
Size,  
Internal  
Diameter  
inches inches  
10  
20  
30  
40  
50  
60  
70  
80  
90  
100  
125  
150  
175 200  
1/4  
3/8  
1/2  
0.364  
32  
72  
22  
49  
92  
18  
40  
73  
15  
34  
63  
14  
30  
56  
12  
27  
50  
11  
25  
46  
11  
23  
43  
10  
22  
40  
9
8
8
7
6
0.493  
0.622  
21  
38  
18  
34  
17  
31  
15  
28  
14  
26  
132  
3/4  
1
0.824  
1.049  
1.380  
1.610  
2.067  
278  
520  
190  
350  
152  
285  
590  
890  
130  
245  
500  
760  
115 105  
96  
90  
84  
79  
72  
64  
59  
55  
215 195 180  
440 400 370  
670 610 560  
170  
350  
530  
160  
320  
490  
930  
150  
305  
460  
870  
130  
275  
410  
780  
120  
250  
380  
710  
110 100  
225 210  
350 320  
650 610  
1 1/4  
1 1/2  
2
1050  
1600  
3050  
730  
1100  
2100 1650 1450  
1270 1150 1050 990  
Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet  
Tube  
size,  
inches  
EHD*  
10  
20  
58  
30  
47  
96  
40  
41  
50  
37  
60  
34  
1/2  
3/4  
1
18 EHD 82  
23 EHD 161 116  
83  
75  
68  
30 EHD 330 231 188  
162  
325  
144  
292  
131  
267  
* EHD = Equivalent Hydraulic Diameter. The greater the  
value of EHD, the greater the gas capacity of the tubing  
.
1 1/4 37 EHD 639 456 374  
FOR LP GAS  
Maximum Capacity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases (at 11 inches Water Column Inlet  
Pressure) (Based on a Pressure Drop of 0.5 Inch Water Column).  
* EHD = Equivalent Hydraulic Diameter. The greater the  
value of EHD, the greater the gas capacity of the tubing.  
Nominal  
iron  
Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet  
Tube  
size  
Black Iron Pipe  
pipe  
Length of Pipe, Feet  
inches  
EHD*  
Inches  
10  
20  
30  
40  
50  
60  
80 100 125 150 200  
10  
20  
30  
74  
40  
64  
50  
58  
60  
53  
1/2  
3/4  
1
291 200 160 137 122 110 94  
84 74 67 58  
1/2  
3/4  
1
18 EHD 129 91  
608 418 336 287 255 231 197 175 155 140 120  
1145 787 632 541 480 434 372 330 292 265 227  
23 EHD 254 183 151  
30 EHD 521 365 297  
131  
256  
118  
227  
107  
207  
Maximum Capacity of Semi-Rigid (flexible, non  
corrugated) Tubing in Thousands of BTU per Hour of  
Undiluted Liquefied Petroleum Gases (at 11 inches  
Water Column Inlet Pressure).  
Copper  
Outside  
diameter  
Inch  
Length of Tubing, Feet  
10 20  
39 26  
92 62  
30 40  
21 19  
50 41  
50  
_
60 70 80 90 100  
3/8  
1/2  
_
_
_
_
_
37  
79  
35 31 29 27 26  
72 67 62 59 55  
(Based on a Pressure Drop of 0.5 Inch Water Column)  
5/8 199 131 107 90  
* Source National Fuel Gas Code NFPA 54, ANSI  
Z223.1 - No Additional Allowance is necessary for an  
ordinary number of fittings  
3/4 329 216 181 145 131 121 112 104 95 90  
Fig. 29  
24  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
or flush the lines before connecting to the water  
heater.  
3.9 Water connections  
Warning: This heater is not approved  
B Full port shutoff valves should be installed on both  
the cold water supply and hot water outlet lines to  
facilitate servicing the heater (see Fig. 31).  
for preheated water applications.  
See chapter 3.11 for approved  
recirculating application.  
B For installation on a private well system with the use  
of a pressure tank, the lowest pressure range setting  
recommended is 40-60 psi (2.75 and 4.15 bar).  
Warning:  
In applications where inlet water  
temperature can exceed 140°F (60ºC), a  
3-way valve or mixing valve must be  
installed before the appliance to prevent  
water exceeding 140°F (60°C) from  
entering the appliance.  
3.10 Water quality  
Water quality can have an impact on appliance  
longevity and may not be covered under the  
manufacturer's warranty.  
For water analysis data call your local water department,  
or if on a well, have well water analyzed periodically. If  
water quality exceeds one or more of the values  
specified below, Bosch recommends consulting a local  
water treatment professional for water softening/  
conditioning options.  
B When facing the heater, the ¾” cold connection is on  
the bottom right and the hot connection is on the bot-  
tom left. Centrally locating the water heater is recom-  
mended to keep hot water distribution times even  
throughout the structure.  
Description  
pH  
Max. Levels  
pH  
6.5 - 8.5  
500  
TDS (total Dissolved  
Solids)  
mg/l or ppm  
mg/l or ppm  
mg/l or ppm  
mg/l or ppm  
mg/l or ppm  
mg/l or ppm  
mg/l or ppm  
mg/l or ppm  
100  
(6 grains)  
Total hardness  
Aluminum  
Chlorides  
Copper  
COLD  
2.0  
250  
1.0  
HOT  
Fig. 30  
B The use of unions when connecting both water  
pipes to the inlet and outlet connections is  
required. This will facilitate any necessary  
servicing.  
Iron  
0.3  
B Plastic or PEX type plumbing line materials are not  
suitable for connecting directly to the water heater.  
Manganese  
0.05  
5.0  
B Although water piping throughout the building may  
be other than copper, we recommend that copper or  
suitably rated stainless steel flex line piping be used  
for the water connections for 1.5’ on either side of  
the water heater (follow local codes if more  
stringent).  
Zinc  
Table 13  
B Never sweat any piping directly to or beneath  
the water connections, as damage can occur to  
the internal water valve from heating of the  
pipe.  
B Keep water inlet and outlet pipes to no less  
than ¾" (19.05mm) diameter to allow the full  
flow capacity.  
B If the cold and hot connections to the heater are  
reversed, the heater will not function. Be certain there  
are no loose particles or dirt in the piping. Blow out  
25  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
Connecting the pressure relief valve (PRV)  
3.11 Domestic hot water recirculation  
A listed pressure relief valve supplied with the heater  
must be installed at the time of installation. No valve is  
to be placed between the PRV and the heater. No  
reducing coupling or other restriction may be installed  
in the discharge line. The discharge line must be a min-  
imum of 4” above a drain and installed such that it  
allows complete drainage of both the PRV and the line.  
The discharge line must be placed where it will not  
cause any damage.  
The location of the PRV must be readily accessible for  
servicing or replacement, and be mounted as close to  
the water heater as possible. See Fig. 31. To install the  
PRV, a suitable fitting connected to an extension on a  
“T” fitting can be sweated to the hot water line.  
Support all piping.  
Although recirculation directly through the tankless  
water heater is allowed, temperature stability is  
improved by recirculating through a mini-tank as shown  
in Fig. 32. By using the design in Fig. 32, there is no  
recirculation of hot water through the tankless water  
heater and therefore, does not affect the heat  
exchanger warranty. Direct recirculation through the  
tankless water heater is permissible, however, the heat  
exchanger warranty is reduced; contact Bosch  
Thermotechnology for further installation requirements.  
The following drawing is provided to outline one  
possible recirculation design using the water heater in  
conjunction with an Ariston mini tank water heater. This  
schematic is for illustration only and must not be used  
for actual installation without appropriate engineering  
and technical advice from  
a
properly licensed  
professional in the locality where the installation is  
made.  
GWH  
2700  
ES  
5
2
4
1
3
Fig. 31 Plumbing Connections (with shutoff valves)  
and Pressure Relief Valve  
6720608158-77.1AL  
Ariston Minitank  
1
Water filter  
Fig. 32 Recirculation application  
1
2
3
4
5
Full port isolation valve  
Circulator (pump)  
Check valve  
PRV  
Expansion tank  
The use of a small electric mini-tank water heater (4-6  
gallon size) should be used for this application and  
designed so the pump will circulate the water through  
the mini-tank and the building's hot water return loop  
only. Timed or thermostatically controlled operation of  
the pump is commonly done. Contact Bosch  
Thermotechnology if further information is needed.  
26  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Installation instructions  
B Record lowest operating gas pressure reading in  
table 15.  
3.12 Measuring gas pressure  
Confirm gas pressure upon installation.  
Connecting manometer  
Gas pressures lower than 3.5" W.C. for Natural Gas or  
8" W.C. for LPG will result in insufficient degree rise to  
the hot water being used, reduced hot water volume,  
possible error code faults and must be corrected. See  
Gas Connections, chapter 3.8, page 22.  
B Shut off gas supply at installer supplied shutoff valve  
for this water heater.  
B Remove front cover and locate inlet gas pressure  
measuring point (see Fig. 34).  
B Loosen screw inside left test point fitting (do not  
remove) and connect manometer tube to test point.  
Remove screw completely if correct size tapping is  
available.  
Static Pressure Test  
B Turn gas supply back on.  
B Record static gas pressure reading in table 15.  
Operating Pressure Test  
B Press ON/OFF button to turn off the appliance.  
B Press and hold "Program" (P) button and press ON/  
OFF button to turn appliance ON.  
Fig. 34 Gas pressure test port (left tapping)  
Static Gas Pressure Reading (see Chapter 3.12)  
enter here: ___________________ Date: ___________  
Operating Gas Pressure Reading (see Chapter 3.12)  
enter here: ___________________ Date: ___________  
Table 15  
Fig. 33  
B As soon as '188' is displayed, release "Program"  
, button and the display should read P2.  
B Press  
or  
until P1 appears.  
Note: While in this mode the appliance will run  
constantly at maximum power and allow  
maximum water flow.  
For inlet gas pressure adjustment consider the  
following table:  
Gas type  
NG  
LPG  
3.5” WC  
8” WC  
Table 14  
Minimum inlet gas pressure under full operation  
B Turn on high volume of hot water flow (at least 6  
gpm) and heater will ignite. If heater display reverts to  
P2, open more hot water fixtures to allow sufficient  
flow. Press  
until P1 reappears on display.  
B Operate all other gas appliances on the same gas  
piping system at maximum output.  
27  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Electrical connections  
4
Electrical connections  
4.1 Electrical power supply  
4.2 Position of the fuses in control unit  
To check fuses, proceed as follows:  
Warning:  
For  
safety  
reasons,  
B Remove the front cover, see Fig. 4, page 6.  
disconnect the power supply cord to  
the heater before any service or testing  
is performed.  
B Remove the three screws on front of the control unit.  
Warning: This heater must be  
electrically grounded in accordance  
with the most recent edition of the  
National Electrical Code. NFPA 70. In  
Canada, all electrical wiring to the  
heater should be in accordance with  
local codes and the Canadian Electrical  
Code, CSA C22.1 Part 1. Do not rely  
on the gas or water piping to ground the  
metal parts of the heater.  
Fig. 36  
B Pull control unit free to access and remove the six  
screws from the back cover of the control unit, see  
Fig. 37, pos. 2.  
The water heater requires an electrical power supply  
from a 120VAC / 60Hz properly rated receptacle and  
must be properly grounded.  
B Check the fuses in the printed circuit board, see Fig.  
37, pos. 3.  
The heater is wired as shown in the wiring diagram  
(chapter 9, Fig. 59).  
1
2
Fig. 35 Connecting power supply cord  
3
1
Power cord length: 3ft.  
Note: Outlet appliance is plugged in to should be  
clear from possible water damage.  
6720608158-78.1AL  
Fig. 37 Location of fuses  
B After verifying the fuses mount all parts in reverse  
order.  
28  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Operation instructions  
5
Operation instructions  
Fig. 38  
1
2
3
4
5
6
7
On/Off button  
Reset button  
Program Key  
LCD display  
Up button  
Down button  
LED - Power On indicator or Stand-by  
5.1 LCD Display functions  
Fig. 42 Lock indicator  
Fig. 43 Flame indicator  
Fig. 44 Remote control  
Warning: Do not use any cleaning or  
corrosive agent to clean the window.  
Fig. 39 Power bar indicator  
Fig. 40 Temperature indicator  
Fig. 41 Error indicator  
29  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Operation instructions  
5.2 For your safety read before  
operating your water heater  
5.4 Temperature selection  
To select output water temperature:  
B Press buttons  
temperature.  
or  
in order to reach desired  
Warning: If you do not follow these  
instructions exactly, a fire or explosion  
may result causing property damage,  
personal injury or loss of life.  
A. This appliance is equipped with electronic ignition for  
lighting the main burner. When turning the heater on,  
follow these instructions exactly.  
B. Before operating the unit, press the On/Off button.  
WHAT TO DO IF YOU SMELL GAS  
B Do not try to light any appliance.  
B Do not touch any electric switch; do not use any  
phone in your building.  
Fig. 46  
B Immediately call your gas supplier from a neighbors  
phone. Follow the gas supplier’s instructions.  
Setting the water temperature  
The desired temperature of the hot water can be  
adjusted on the front control panel of the heater.  
The water heater has an electronically controlled gas  
valve that modulates the burner input in response to  
both varying hot water flow rates and/or changes in any  
incoming and outgoing water temperatures.  
B If you cannot reach your gas supplier, call the fire  
department.  
C. Use only your hand to press the on/off control switch.  
Never use tools. Follow these instructions exactly. If  
control switch is jammed, close the gas supply and call  
a qualified service technician. Attempted forceful repair  
may result in a fire or explosion.  
D. Do not use this appliance if any part has been under  
water. Immediately call a qualified service technician to  
inspect the appliance and to replace any part of the  
control system and any gas control which has been  
under water.  
Note: The water heater, running at minimum BTU, may  
still achieve temperatures above the desired set  
temperature. Low flowing fixtures are the leading cause  
of this type of temperature overshoot. To combat this  
symptom, clean fixtures or replace with higher flowing  
ones.  
Saving water resources:  
B Make sure you close all the taps after any use. Avoid  
leaving the taps dripping. Repair any leaking tap.  
5.3 Power  
On  
B Define the temperature you want, in the appliance or  
with the remote control. This way you have the  
precise water flow needed (mixing cold water to  
regulate temperature will increase the water flow with  
consequent waste of water).  
B To start the appliance press the On/Off button.  
Fig. 45  
Off  
B To shut down the appliance press the On/Off button  
again.  
30  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Operation instructions  
5.5 Use of optional remote control  
accessory (part no. TSTAT2)  
Fig. 50 Reset button  
If the problem persists, contact your installer.  
5.8 Program button  
Program button can be used on the appliance and in the  
remote control.  
Fig. 47 Remote control  
The wireless remote control accessory (Fig. 71,  
component 13) and the temperature selector buttons  
on the front of the water heater operate identically.  
Contact your distributor to order the remote control  
accessory. Modification of the water heaters interior  
control unit (Fig. 71, component 16) is required when  
programming the remote control with this heater.  
Programming “Program” function  
Programming actions are similar for both controls  
(appliance control pad and wireless remote control).  
NOTE: up to 6 remote controls can be  
programmed for one single water heater,  
each with a range distance of 98 ft (30 m).  
i
Fig. 51 “Program” key  
5.6 Operation  
B When a hot water tap is opened, main burner ignites  
and LCD displays the symbol  
Memorizing selected temperature  
.
B Press buttons  
memorized.  
or  
to select temperature to be  
B Hold “Program” button for 3 seconds to save  
temperature.  
When LCD stops blinking, temperature is saved in  
memory.  
Fig. 48  
Using “Program” function  
In order to select memorized temperature  
B LCD blinks until selected temperature is reached.  
B Press “Program” key.  
5.7 Reset button  
LCD shows pre-memorized temperature, which is now  
the hot water selected temperature.  
If the LCD shows the error symbol  
power or unplug the heater.  
do not shut off  
See the error code on LCD and consult  
Troubleshooting” section.  
5.9 Locked condition  
This condition is only valid for appliances with remote  
controls.  
Fig. 52 Locked condition  
Fig. 49  
Whenever LCD shows  
the temperature setting  
After  
Troubleshooting” section.  
following  
instructions  
indicated  
in  
cannot be adjusted because the appliance is in use by  
a user which already selected a different temperature.  
Appliance will be automatically unlocked five minutes  
after closing the hot water tap.  
B press reset button to return heater to normal  
operation.  
31  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Maintenance and service  
6
Maintenance and service  
Pressure relief valve  
Warning: Always turn off the electrical  
power supply, turn off the manual gas  
shut off valve and turn off the water shut  
off valves whenever servicing.  
• Manually open the pressure relief valve to ensure  
proper operation.  
Inlet water filter  
• Verify the inlet filter screen is clean and undamaged.  
The inlet water filter is located inside the cold water  
inlet fitting on the right side of the appliance (See  
Fig. 53, page 32). Close installer supplied cold water  
shutoff and loosen slotted screw on inlet fitting.  
Water will drain from the appliance. Remove  
cylindrical filter inside.  
Caution:  
B Check and clean the complete water  
heating system once a year.  
B Carry out a maintenance overhaul if  
necessary. Immediately repair defects to  
avoid damage to the system.  
Annual maintenance table  
Every year  
1. Inspect venting system  
X
X
X
X
X
2. Inspect combustion chamber  
3. Inspect burner  
4. Inspect condensate trap  
5. Inspect water filter  
Table 16 Annual maintenance  
Fig. 53 Water filter  
The unit should be checked once a year by a gas  
technician. If repairs are needed, the repairs should be  
done by a gas technician.  
1
2
Inlet water filter  
Water filter  
Descaling  
• In areas where the water supply has a high mineral  
content (see Table 13, page 25), the heat exchanger  
should be periodically flushed with a descaling  
solution. Scale build up will shorten the life of the  
water heater and damage resulting from scale is not  
covered under warranty. Refer to section 6.3 for  
detailed instructions on descaling the heat  
exchanger.  
6.1 Annual maintenance  
(To remove front cover, see page 6.)  
Venting System  
• Venting system - inspect inside of flue pipe for any  
blockage or restriction. Observe burner flames  
during heater operation. (Vent pipe must be  
removed). Inspect the combustion air inlet pipe for  
blockage or debris. Inspect combustion air and  
exhaust terminations for blockage or debris.  
Heat exchanger fin coils  
• Inspect heat exchanger fincoil for soot build-up or  
blockage. To access fincoil, venting must be  
removed from flue gas exhaust accessory. With  
venting removed and inspect fincoil below with a  
flashlight. If there is evidence of soot build-up or  
blockage, the heat exchanger should be removed by  
a professsional and cleaned thoroughly. To remove  
the heat exchanger, consult service bulletin at  
Combustion chamber  
• Inspect burner observation window (Fig. 64, #10) for  
cracks or spillage of flue gases. Observe burner  
flames during heater operation. Flames should be  
steady and blue with no signs of yellowing. Yellow  
burner flames are an indication of improper  
combustion. Refer to Section 3.4 & 3.3 of this  
manual to ensure that exhaust system and  
combustion air supply meets manufacturer's  
specifications.  
6.2 Winterizing for seasonal use  
Installation instructions state that the water heater must  
not be installed in a location where it may be exposed to  
freezing temperatures. If the heater must be left in a  
32  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Maintenance and service  
space which is likely to experience freezing  
temperatures, all water must be drained from the heater.  
If precautions are not taken, resulting damage will not  
be covered under the warranty. NOTE: Use of agents  
such as anti-freeze is not permitted as they may cause  
damage to the water heater's internal components.  
9. Fill tank with descaling solution so both lines inside  
are submersed. We recommend straight white  
vinegar. If using a commercial descalant, refer to  
manufacturer's instructions on dilution with water.  
10.Operate the circulating pump.  
11.Make sure there are no leaks and the solution is  
flowing from the descaling reservoir through the  
heater and returning to the reservoir.  
1. Press ON/OFF switch on the water heater to turn  
OFF the heater and unplug power supply cord. The  
display should be blank.  
12.Run solution through the heater until the solution  
returning to the descaling reservoir comes out clear.  
(Changing to a fresh solution may be necessary  
during this process).  
2. Shut off gas supply to heater.  
3. Shut off the water supply to the water heater using  
installer supplied shutoff valve.  
13.Disconnect all lines and drain all solution from heat  
exchanger. Properly discard of solution.  
4. Open hot water taps to drain the plumbing system. If  
water continues to flow after 5 minutes, a plumbing  
crossover is present and must be corrected before  
proceeding.  
14.Position a container below the hot water outlet and  
connect cold water supply. Open cold water supply  
isolation valve and flush heat exchanger with clean  
water.  
5. Open service valves (if available) or disconnect inlet  
and outlet water pipes from the water heater. Place a  
small bucket underneath the water heater to catch  
residual water remaining inside the water heater.  
15.Shut cold water shutoff valve and reconnect hot  
water supply to the water heater.  
6. Using an air compressor, blow short bursts of air  
(100psi max) through the outlet water connection  
until there is no water present coming through the  
inlet water connection of the heater.  
16.Reconnect electrical supply to unit, open water  
shutoff valves, and return the unit to service.  
7. Reconnect water fittings and return heater to service  
when danger of freezing has past.  
6.3 Mineral scale build-up  
Periodic descaling may be necessary in areas with high  
mineral content in the water. Scale buildup in the heat  
exchanger may result in lower flow rates, error codes of  
A7 and E9 and boiling sounds (knocking and banging)  
in the heat exchanger.  
Descaling using a pump  
1. Disconnect electrical supply from the water heater.  
2. Shut off the water supply to the water heater using  
(installer supplied) shutoff valve.  
3. Open hot water taps to drain and relieve pressure  
from the plumbing system.  
4. Drain water from the unit's heat exchanger by  
disconnecting inlet and outlet water connections  
from the heater.  
Fig. 54  
5. Connect a line (A) from the outlet of the circulating  
pump (installer supplied) to the inlet water fitting on  
the water heater (see Fig. 54).  
6.4 Adjusting CO (carbon dioxide)  
2
The CO2 can only be adjusted by a certified gas  
technician with a calibrated CO2 analyzer.  
6. Using another line (B), connect to the water outlet  
fitting on the water heater. Route the other end of this  
line into a descaling reservoir.  
Caution: One factor that may affect  
CO2 levels is improper gas pressure.  
Please see Chapter 3.12 for the  
procedure to measure gas pressure  
and record your findings below:  
7. Using a 3rd line (C) from the descaling reservoir,  
connect to the inlet side of circulating pump. Install a  
filter on the end of this line in the descaling reservoir.  
8. Make sure all connections are "water tight.".  
33  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Maintenance and service  
Static Gas Pressure:  
“ WC  
“ WC  
B Record the CO2 reading in P1 below. (Analyzer  
reading may take several minutes to stabilize).  
P1 Operating Pressure:  
B Press the ‘ ’ button until P2 appears. Unit will  
ramp down to low fire and the flow should decrease.  
The P1 minimum operating gas pressure is 3.5" WC for  
Natural Gas and 8" WC for Propane. Do not proceed in  
adjusting CO2 until pressure is at or above these levels,  
but not to exceed 10.5” WC for Natural Gas and 13”  
WC for Propane.  
B Record the CO2 reading in P1 and P2 below.  
P2 CO2 Reading:  
% CO2  
P1 CO2 Reading:  
% CO2  
A. Once Gas Pressure is adequate  
C. Adjusting CO2:  
B Press ON/OFF button to turn off the heater.  
Note: P1 adjustment will change the P2 reading.  
Confirm the P1 value BEFORE adjusting the P2 level.  
B Remove brass flat head screw on the exhaust collar  
as seen in Fig. 55.  
1. If P1 CO2 level is off:  
B Insert CO2 analyzer probe into the measuring port.  
The tip of the probe should be in the center of the flue  
pipe (approx 1.5" inserted). Avoid air gaps between  
probe and measuring port as they can alter readings.  
B Loosen yellow painted philips screw (1) and cover  
should rotate down (2) revealing a recessed brass  
slotted screw. Fig. 57.  
B Turning the slotted screw counter clockwise will  
raise P1 CO2 levels and clockwise will lower P1  
CO2 levels. Adjustments to the slotted screw will  
also change P2 CO2 levels.  
B After bringing the P1 CO2 readings in proper range,  
press the  
button to enter the P2 mode. Verify  
CO2 readings in P2 mode.  
2. If P2 CO2 level is off:  
B Remove yellow painted #40 Torx cover from the front  
of the gas valve. (Fig. 58) A plastic #40 Torx screw  
will be revealed.  
Fig. 55 Measuring port  
B Turning the plastic #40 Torx screw counter  
clockwise will lower P2 CO2 levels and clockwise  
will raise P2 CO2 levels.  
B While holding the Program (P) button in, press the  
ON/OFF button to turn ON the heater (see Fig. 56).  
As soon as ‘188’ flashes on the display, release the  
Program button. The display should now read P2.  
Note: This screw adjustment is very sensitive and  
should be made in small increments. It may take several  
minutes for readings to stabilize.  
Press  
button until “P1” appears on display.  
3. Verify both P1 and P2 CO2 readings are within the  
ranges specified in table 17. Repeat steps 1 and 2 as  
necesssary until CO2 values are within the specified  
ranges.  
4. Once CO2 values are within the specified ranges,  
verify the CO readings on P1 and P2 do not exceed  
values shown in table 17. If values exceed this limit,  
inspect vent system and fin coils (chapter 6.1, page 32)  
for blockage.  
D. Returning to Service:  
Fig. 56  
1. Return slotted screw cover to original position and  
tighten philips screw.  
2. Reinstall Torx cover.  
B. Measuring CO2 (combustion cover must be  
installed):  
3. Remove CO2 analyzer probe and reinstall flathead  
screw with gasket in exhaust collar.  
4. Press ON/OFF button to turn OFF the heater and  
then turn ON the heater.  
B Open all hot water taps to achieve a flow rate of at  
least 6 gallons per minute. (1 tub and 2 sinks should  
be sufficient). If heater display reverts to P2, open  
more hot water fixtures to allow sufficient flow. Press  
5. Heater is ready for normal operation.  
’ until P1 reappears on the display.  
34  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Maintenance and service  
Max. CO  
level  
(measured)  
CO2 range (%)  
Nat. Gas  
7.5 % - 8.1 %  
2.3 % - 2.6 %  
LP Gas  
max. input  
min. input  
P1  
P2  
< 250 ppm  
< 60 ppm  
max. input  
min. input  
P1  
P2  
8.7 % - 9.3 %  
2.7 % - 3.0 %  
< 250 ppm  
< 60 ppm  
* Values above are for climate controlled conditions.  
Inputs such as gas pressure, heating value of the gas,  
humidity and temperature of combustion air all impact CO  
and CO2 values. Changes in these inputs can result in  
different CO and CO2 values on the same appliance.  
Table 17 CO2 & CO target numbers  
Final Readings  
P2 CO2 Reading:  
% CO2  
% CO2  
P1 CO2 Reading:  
Fig. 57 Adjusting P1 CO2 level  
6720608158-38.1AL  
Fig. 58 Adjusting P2 CO2 level  
35  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Maintenance and service  
Refer to chapter 6.6 Control board diagnostics (page  
37) regarding how to access these P-modes.  
6.5 Program values  
This section describes details on programming the  
appliance. For most applications the factory default  
values will robust and stable operation. Only adjust the  
factory settings if the installation requires changes as  
indicated in the appropriate section of this manual.  
Caution: Misadjusted program  
values can lead to appliance  
malfunction, errors, and service  
calls.  
Program Description  
Factory Default MIN MAX  
Comment  
P1  
Maximum Power  
NG: 48, LP: 46  
21  
NG: 50, LP: 49 see chapter 3.12, page 27.  
note: reducing P1 values below  
maximum will reduce maximum  
power of the appliance.  
P2  
P3  
Minimum Power  
7
7
20  
6
see chapter 3.3.6, page 17  
see chapter 5.5, page 31  
Remote Con-  
trols installed  
_0  
_0  
P4  
Access to Diag-  
nostic Mode  
E
0d  
10f  
see chapter 6.6, page 37  
contact Bosch for details  
P5  
P6  
Cascade Mode  
NO  
°F  
NO  
°F  
CC  
°C  
Temperature  
Unit  
P7  
P8  
Appliance Type  
Back light  
NO  
dE  
Cd  
dE  
NO  
ON  
Condensing / Non-condensing*  
dE turns back light off after 60  
seconds from last button  
pushed, ON turns backlight on  
permanently  
P9  
Fan Purge  
runs secondary and primary fan  
when P9 is selected by  
depressing the “P” - button  
Table 18 Program values, factory default settings and ranges.  
* Incorrect setting causes errors.  
36  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Maintenance and service  
6.6 Control board diagnostics  
Diagnostic menu  
1. Turn on/off switch on water heater to off (O) position.  
E
Entry/Exit into sub-modes  
Set-point temperature (°F)  
2. Press and hold the program (  
) button while  
0d  
1d  
2d  
3d  
4d  
5d  
6d  
7d  
8d  
9d  
turning the on/off switch to the on (I) position. The  
display will cycle through a startup procedure  
including the software version.  
Inlet water temperature (°F)  
Outlet water temperature (°F)  
Water flow (gallons/min)  
Gas type (LP or NG)  
3. Release the '  
' button when '188' appears on the  
display. The display should read 'P2' when the  
program button is released. If not, repeat process.  
4. Press and release the '  
' button on the control  
Fan speed (Hz)  
panel until the display reads 'P4'. You are now in the  
diagnostic mode of the control board.  
Burner power (%)  
Maximum power (kW)  
Back flow temperature (°F)  
5. When the display reads 'P4', press and release the  
'
'E'.  
' button once again and the display should read  
Flue gas temperature (°F)1)  
not used, settting 00  
6. Use the '  
' and '  
' button on the control board  
to cycle through different diagnostic modes  
available.  
1F  
2F  
3F  
4F  
5F  
6F  
7F  
8F  
9F  
Most recent error/failure  
2nd most recent error  
3rd most recent error  
4th most recent error  
5th most recent error  
6th most recent error  
7th most recent error  
8th most recent error  
9th most recent error  
10th most recent error  
7. Once in the selected diagnostic mode of your  
choice, press and release the '  
the diagnostic information.  
' button to display  
EXAMPLE: to read the flow rate in gallons per minute  
while the unit is flowing water, cycle to the '3d' mode  
and press the '  
' button. A reading of 25 on the  
display would indicate the heater is reading a flow rate  
of 2.5 gallons/minute.  
8. Once the information is obtained, press the '  
'
button again to return to the diagnostic mode menu  
and scroll to addition diagnostic information.  
10F  
9. To exit the diagnostic mode of the heater, use the  
'
Table 19  
' or '  
' button until the display reads 'E'.  
1)  
Available only on model GWH C800 ES  
10.Press the '  
should read P4.  
' button once again and the display  
11.Turn the on/off switch off (O) and back on (I) again  
to return heater to normal function.  
37  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Troubleshooting  
7
Troubleshooting  
and mixing valves are common causes of plumbing  
crossovers.  
Warning: If you are unable to perform  
the tasks listed below, or need  
additional assistance please contact  
your original installer or licensed gas  
technician.  
8. With the ON/OFF switch turned to OFF (O) position  
and the power supply cord unplugged, remove the  
unit's front cover (See Page 6. Fig 3). Check wire  
connections between the water valve, control unit  
and electrode set. See chapter 12.1, page 49 for  
location of these parts.  
7.1 Introduction  
Many of the questions customers ask regarding  
operation of this unit can be answered by following the  
troubleshooting steps as outlined below. Visit our web  
troubleshooting and service bulletins. For best results,  
perform each step before proceeding to the next. The  
suggested solutions may require that the cover be taken  
off. (See Page 6. Fig. 3).  
7.3 Water is too hot  
1. Selected temperature on the unit is set too high. To  
lower output temperature, see chapter 5.4, page 30.  
2. Clean inlet filter screen per chapter 6.1, page 32.  
3. Inspect the water path for obstructions. Make sure all  
showerheads, faucet aerators and whole house  
filters are clear of debris.  
4. Confirm the heater's gas type coincides with the type  
of gas being supplied. See Fig. 2, page 6 for location  
of rating plate.  
7.2 Burner do not ignite when hot  
water is turned ON  
1. If the display is blank, verify power to outlet.  
(120VAC/60Hz properly grounded circuit required).  
Verify that the heater ON/OFF button is turned ON.  
5. Avoid restrictive outlets. Clean all showerheads and  
faucet aerators. It may be necessary to upgrade to  
higher flow rate shower heads if allowable by local  
code.  
2. Verify the fuses in the control board are good. See  
Section 4.2, page 28 of the installation manual for  
fuse locations.  
6. In areas where the water has a high mineral content,  
periodic descaling may necessary. See chapter 6.3,  
page 33 for directions.  
3. Make sure cold water inlet connection is plumbed to  
the right side of heater when facing unit. See Fig. 30,  
page 25.  
7. Ensure the outlet temperature sensor is making  
contact and firmly mounted on the hot water pipe.  
4. A minimum of 0.65 gallons per minute (GPM) (2.5 l/  
m) is required to activate the heater. A quart  
container should fill in 25 seconds or less to activate  
heater. In areas of warm inlet water temperatures, the  
heater may increase activation rate to as high as 1.6  
gallons per minute (GPM) to prevent overshooting of  
set temperature.  
7.4 Water is not hot enough  
1. Selected temperature on the unit is too low. To raise  
output temperature, see chapter 5.4, page 30.  
2. Clean inlet filter screen. See chapter 6.1, page 32.  
3. Inspect the water path for obstructions. Make sure all  
showerheads, faucet aerators and whole house  
filters are clear of debris.  
5. Clean inlet filter screen per chapter 6.2, page 32.  
6. Inspect the water path for obstructions. Make sure all  
showerheads, faucet aerators and whole house  
filters are clear of debris.  
4. Confirm the heater's gas type coincides with the type  
of gas being supplied. See Fig. 2, page 6 for location  
of rating plate.  
7. The heater activates when the water flow through the  
unit is at or above the required minimum of 0.65  
GPM (2.5 l/m). A crossover in the plumbing creates  
back pressure on the water flowing through the  
heater. Therefore, a higher flow rate than normal is  
needed to force the heater to activate. To check for  
a plumbing crossover, shut off the cold water supply  
to the water heater. Then open all of the hot water  
taps served by the heater. Wait 10 minutes and  
check for water flow at taps. There should be no  
water flowing. Any continuous flow of water, small or  
large, indicates a crossover is present and must be  
corrected. Consult a professional plumber for help in  
correcting a crossover. Failing single lever faucets  
5. Check inlet gas particle screen for blockage at gas  
inlet connection on bottom of unit.  
6. Verify gas pressure is in accordance with  
specifications in chapter 3.12, page 27. A gas  
pressure reading is needed to proceed further.  
Contact your original installer or a local certified gas  
technician to obtain this reading.  
7. Cold water is mixing into the hot water lines  
(plumbing crossover). A plumbing crossover can  
unintentionally mix cold water with the hot water  
leaving the heater. The end result is a cooler water  
temperature than desired. To check for a plumbing  
crossover, shut off the cold water supply to the water  
38  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Troubleshooting  
heater. Then open all of the hot water taps served by  
the heater. Wait 10 minutes and check all taps for  
water flow. There should be no water flowing. Any  
continuous flow of water, small or large, indicates a  
crossover and must be corrected. Consult a  
professional plumber for help in correcting a  
crossover. Failing single lever faucets and mixing  
valves are common causes of plumbing crossovers.  
higher pressure cold water at the tap, the lower  
pressure hot water can be overpowered. This will  
shut down the burners because the hot water flow  
rate fell below the minimum flow rate required for  
activation. Verify inlet filter screen is clean and clear  
of debris. See chapter 6.1, page 32 for inlet filter  
cleaning instructions.  
3. Heater deactivated by temperature balancing valves.  
If the outlet water temperature is set too high, the  
heater can produce temperatures that are too hot. A  
temperature balance shower valve will automatically  
mix in cold water to reduce the hot water  
temperature. In the event of any temperature  
instability at a fixture using a temperature balancing  
valve, refer to the valve manufacturer for instructions  
on internal adjustment setting. An adjustment should  
be made to minimize the amount of cold water the  
valve is adding. Additionally, the temperature setting  
on the heater can be lowered to prevent the  
temperature balance valve from mixing in too much  
cold water.  
8. Ensure the outlet temperature sensor is making  
contact and firmly mounted on the hot water pipe.  
7.5 Low water flow/pressure  
1. Too many hot water applications are being used  
simultaneously or too much flow is demanded. The  
water heater will effectively support two 2.0-2.5  
GPM shower heads simultaneously or multiple sink  
applications. Greater draws will result in a water  
pressure drop and reduced flow at taps.  
2. Ensure that gas pressure is in accordance with  
specifications in chapter 3.12, page 27. A gas  
pressure reading is needed to proceed further.  
Contact your original installer or a local certified gas  
technician to obtain this reading. If gas pressure is  
inadequate, the water heater will close its motorized  
water valve, reducing the hot water flow rate in an  
attempt to reach the selected output temperature.  
4. Inlet water pressure is erratic due to fluctuating  
supply water pressure. For installation on a private  
well system with the use of a pressure tank, the  
lowest pressure range setting recommended is 40-  
60 psi (2.75 - 4.15 bar). Consult your installer or  
local plumber for effective ways to maintain constant  
water pressure to the water heater when on a well  
system.  
3. If selected temperature on the unit is set too high for  
the demanded flow rate, the water heater will close  
its motorized water valve, reducing the hot water flow  
rate in an attempt to reach the selected output  
temperature. Lowering the selected temperature will  
allow the motorized water valve to open up for  
increased water flow rate.  
7.7 Noisy burner/heater during  
operation  
1. Sealed combustion leak. Make sure combustion  
cover is securely fastened. Ensure the exhaust vent  
adaptor is properly sealed with supplied gasket.  
Leaky seals create improper combustion resulting in  
noise.  
4. Clean inlet filter screen per chapter 6.1, page 32.  
5. Inspect the water path for obstructions. Make sure all  
showerheads, faucet aerators and whole house  
filters are clear of debris.  
2. Improper venting. Venting that is unsealed, the wrong  
material, too big in diameter or too long in run will  
result in unstable burner flames and noise. Ensure  
venting is proper and in accordance with  
specifications in chapter 3.3, page 9.  
7.6 Hot water temperature fluctuates  
at tap  
1. Hot water is very hot out of the tap, requiring mixing  
of cold water in order to attain a useable hot water  
temperature. The addition of too much cold water will  
overpower the hot water flow from the tankless water  
heater.  
3. Lack of adequate combustion air. Drawing  
combustion air from a room area of inadequate size  
will result in unstable burner flames and noise.  
Improper use of piping for combustion air will result  
in unstable burner flames and noise. Ensure  
adequate combustion air is provided to the unit in  
accordance with specifications in Section 3.4, page  
20, Combustion Air Requirements.  
This slows the flow within the tankless water heater,  
decreasing it below activation point, which shuts off  
the burners. The end result is nothing but cold water  
coming out of the outlet.  
service bulletin on overcoming temperature  
fluctuations.  
4. Cross contamination. Ensure that intake and exhaust  
terminations maintain minimum required clearances  
stated in the manual. Cross contamination between  
intake and exhaust may cause unstable burner flames  
and noise.  
2. Unbalanced pressure in water lines. Any restriction in  
the water heater, such as a clogged inlet filter screen,  
can result in unequal pressures between the cold  
and hot water lines. In such cases, when mixing in the  
39  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Troubleshooting  
5. Lack of adequate gas pressure. Inadequate gas  
pressure will cause the fuel-to-air mixture (CO2) to be  
out of adjustment. This will result in unstable burner  
flames and noise. Ensure gas pressure is in  
accordance with specifications in section 3.12, page  
27 Measuring Gas Pressure. A gas pressure reading  
is needed to proceed further. Contact your original  
installer or a local certified gas technician to obtain  
this reading.  
6. Verify proper CO2 readings per chapter 6.4, page  
33. CO2 adjustments must be done by a certified  
gas technician with a calibrated combustion gas  
analyzer.  
40  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Problem solving  
8
Problem solving  
8.1 Error code diagnostics  
To remove error code from the  
display, press the reset button.  
i
Display  
Cause  
Solution  
Fault in the flue gas limiter.  
1. Check continuity of the flue gas limiter (see Fig. 64, page 49).  
Go to steps two and three to determine air box temperature  
sensor fault and replace it.  
2. Check for flue gas leakage around the top and bottom seals of  
heat exchanger as well as the viewing window.  
3. Check that venting is within specifications (see Section 3.3).  
Long vent lengths, venting with more than three elbows, blocked  
vent or combination venting may cause this failure.  
4. Check that flue gas limiter connector and spade connections  
are secure.  
5. Unplug heater and check the two main plug connections inside  
the control board.  
Appliance selection on “P7” mode 1. Check “P7” mode: water heater requires setting “NC”.  
is not correct.  
2. Check jumper and connection on sensor at upper right hand  
corner of heat exchanger.  
3. Measure jumper resistance, must be 115-125 ohms.  
Backflow temperature sensor 1. Check backflow temperature sensor connection and resistance.  
defect - happens if sensor is See Fig. 62 page 47 and Fig. 64, page 49  
disconnected or short circuit. 2. Replace backflow temperature sensor.  
,
.
Outlet temperature sensor fault 1. Check red wire connections at hot water temperature sensor.  
(Temperature below freezing or Clean terminals with an eraser. If badly corroded, replace sensor  
above 210°F).  
and wire harness. See Fig. 64, page 49.  
2. Sensor may trip if water temperature drops below freezing to  
protect heater from freezing conditions. Any damage due to  
freezing conditions is not covered under warranty.  
3. Clean inlet filter screen and clear any debris out of shower  
heads, faucet aerators and whole house filters.  
4. In areas where water has a high mineral content, periodic  
descaling may be necessary.  
Table 20  
* By installer or service technician only.  
41  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Problem solving  
Display  
Cause  
Solution  
(Flashing)  
Outlet temperature sensor not 1. Check that the sensor is firmly attached to the hot water pipe  
expected  
sensing  
temperature.  
output (see Fig. 70, page 55).  
2. Clean inlet filter screen and clear any debris out of shower  
heads, faucet aerators and whole house filters.  
3. Check venting specifications are met. Long vent lengths,  
venting with more than three elbows, blocked vent or combination  
venting may cause this failure.  
4. Check gas pressure. Low gas pressure may prevent the heater  
from reaching desired output temperature.  
5. Check supply voltage. It must be 120VAC and properly  
grounded.  
6. Possible defective control unit call Bosch Water Heating for  
further instructions.  
7. Ensure that outlet temperature sensor is not placed on any  
bends in the hot water pipe or misreading may occur.  
Primary fan rotation too low on 1. Disconnect power supply cord and check wire connections on  
operation.  
back side of primary fan and the two connectors on the control  
board (see Fig. 71, page 56).  
2. Check supply voltage. It must be 120VAC and properly  
grounded.  
3. Check venting specifications are met. Long vent lengths,  
venting with more than three elbows, blocked vent or combination  
venting may cause this failure.  
4. Ensure intake and exhaust terminations maintain the required  
minimum clearances stated in the manual. Cross contamination  
between intake and exhaust may cause the fan to alter its  
rotational speed.  
5. Check gas pressure. Low gas pressure may cause the fan to  
change its speed to meet desired temperature.  
6. Possible defective control unit call Bosch Water Heating for  
further instructions.  
No rotational speed sensor signal 1. Disconnect power supply cord and check wire connections on  
from primary fan.  
back side of primary fan and the two connectors on the control  
board (see Fig. 71, page 56).  
2. Check supply voltage. It must be 120VAC and properly  
grounded.  
3. Possible defective component in fan or defective control unit  
call Bosch Water Heating for further instructions.  
(Flashing)  
Water flow signal over specified 1. Disconnect power supply cord and check wire connections on  
water valve and the two connectors on the control board (see  
Fig. 71, page 56).  
maximum value.  
Water flow > 10 gallon/min.  
2. Excessive water pressure and flow. Ensure water pressure is  
less than 150psi and flow rate is below 10 gallons per minute.  
Internal hardware/software failure.  
1. Disconnect power supply cord and check the two wire and  
ground connections on control board as well as ground connection  
on heater chassis.  
2. Pushing the wrong combination of buttons on the control unit  
can create confusion among the microprocessors inside. In this  
case, the error code should not happen more than once or twice.  
Turn off the water heater. Turn water heater back on and try  
resetting error code. Use the reset button (  
codes.  
) to reset any error  
3. Possible defective control unit. Call Bosch Water Heating for  
further instructions.  
Table 20  
* By installer or service technician only.  
42  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Problem solving  
Display  
Cause  
Solution  
Over-temperature detected by 1. Check that the sensor is firmly attached to the vertical section of  
outlet temperature sensor on hot the hot water pipe (see Fig. 70, page 55).  
water pipe.  
Temperature > 185°F  
2. Check red wire connections at outlet temperature sensor.  
Clean terminals with an eraser. If badly corroded, replace sensor  
and wire harness. Check sensor resistance (see Fig. 60  
46  
3. Clean inlet filter screen per chapter 6.2  
,
page  
.
,
page 32 and clear any  
debris out of shower heads, faucet aerators and whole house  
filters.  
4. In areas where water has a high mineral content, periodic  
descaling may be necessary. See chapter 6.3  
,
page 32 for  
directions.  
Cold water temperature sensor 1. Check connector on wires coming from top of watervalve for a  
fault.  
secure connection. See Fig. 64, page 49.  
2. Sensor may trip if water temperature drops below freezing to  
protect heater from freezing conditions Any damage due to  
freezing conditions is not covered under warranty.  
Backflow temperature sensor over 1. Check combustion air and backflow vent piping for blockage.  
309°F. 2. Check if secondary fan connections are disconnected.  
The appliance will close the burner 3. Check venting specifications are met. Long vent lengths,  
and lock.  
venting with more than three elbows, blocked vent or combination  
venting may cause this failure.  
4. Check sensor resistance (see Fig. 62 page 47).  
,
Overheat sensor (ECO) open 1. Disconnect power supply cord and check wire connections on  
circuit (should reset when cooler overheat sensor (top right of heat exchanger) and the two  
temperatures are detected).  
connectors on the control board. See Fig. 64, page 49.  
2. Check white wire connections at overheat sensor. Clean  
terminals with an eraser. If badly corroded, replace sensor and  
wire harness.  
3. Check venting specifications are met. Long vent lengths,  
venting with more than three elbows, blocked vent or combination  
venting may cause this failure.  
4. Clean inlet filter screen and clear any debris out of shower  
heads, faucet aerators and whole house filters.  
5. In areas where water has a high mineral content, periodic  
descaling may necessary, see chapter 6.3  
.
6. Unplug power supply cord to the water heater. Open a hot  
water tap for several minutes to allow cold water to pass through  
heat exchanger. Close hot water tap and disconnect lead wires to  
overheat sensor. Using a multimeter, check continuity through  
overheat sensor contacts. Replace sensor if open.  
Table 20  
* By installer or service technician only.  
43  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Problem solving  
Display  
Cause  
Solution  
No flame ionization detected with 1. Verify that all manual gas shut off valves are open.  
water flow.  
2. Check gas type, see Fig. 2, page 6.  
3. Reset error code and open a water tap to cycle the heater in an  
effort to purge air on new installations. Cycling hot water tap on  
and off multiple times may be necessary. If heater still faults with  
EA error code, have a licensed gas technician properly purge air  
out of the gas line leading to the water heater.  
4. Check three wire connections to ignition group on the lower  
front of the heat exchanger are secure.  
5. Check gas pressure, see chapter 3.12 page 27.  
,
6. Check venting specifications are met. Improper venting may  
cause premature failure of the flame sensor rod.  
7. Check that the minimum power fan speed has been adjusted to  
the proper value. See page 18.  
8. Observe inside the viewing window of the heat exchanger when  
a hot water tap is opened. Sparking should be followed by a  
steady blue flame. If flame is unstable or yellow with proper gas  
pressure, confirm CO2 readings per section 6.4  
.
Ionization failure during operation.  
1. Check gas type, see Fig. 2 page 6  
,
.
2. Check three wire connections to ignition group on the lower  
front of the heat exchanger are secure.  
3. Check venting specifications are met. Improper venting may  
cause unstable burner flames and loss of flame ionization.  
4. Check that the minimum power fan speed has been adjusted to  
the proper value. See page 18.  
5. Check gas pressure, see section 3.12 page 27.  
,
6. Check and adjust CO2 readings, see section 6.4, page 33.  
Ionization error at standby.  
1. Loose connection to the flame ionization rod. Verify that the  
thinner wire leading from the control unit is securely connected to  
the flame sensor located on the lower front of the heat exchanger.  
See Fig. 64, page 49.  
2. Flame ionization rod or control unit may be damaged. Contact  
Bosch Water Heating for further instruction.  
Gas leakage error, gas valve circuit 1. Disconnect power supply cord and check wire connections on  
not closing properly.  
gas valve and the two connectors on the control board.  
2. Flow water out of a hot water tap above the minimum activation  
point of 0.65 GPM. Measure voltage at the gas valve wire plug  
connection. The voltage should measure 24VDC between the left  
pair of wires and 24VDC between the right pair of wires when the  
unit is operating. If voltage is not proper, contact Bosch Water  
Heating for further instruction.  
3. Gas valve may be defective, contact Bosch Water Heating for  
further instruction.  
Table 20  
* By installer or service technician only.  
44  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Electrical diagram  
9
Electrical diagram  
16  
15  
13  
12  
E
PS  
20  
M
M
M
11  
10  
19  
T=104°C  
T=220°F  
9
18  
T=110°C  
T=230°F  
8
FS  
7
6
Casc.  
input  
5
Casc.  
output  
Back flow  
4
3
2
1
17  
16  
...  
1
20  
...  
1
21  
JP2  
14  
JP8  
JP6  
JP7  
JP5  
22  
6720608542-04.1AL  
Fig. 59 Electrical scheme  
1
Intlet water temperature sensor  
Outlet water temperature sensor  
Backflow temperature sensor  
Cascading output connection  
Cascading input connection  
Ionization sensor  
2
3
4
5
6
7
Water flow sensor  
Flue gas limiter  
8
9
Heat exchanger overheat sensor (ECO)  
Gas valve  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
Jumper resistance  
Water valve  
Primary fan  
ON/OFF switch  
Secondary fan  
AC plug  
Main connection  
Ignition electrodes  
Ground post  
Antifreeze kit connection  
Fuse  
Fuse  
45  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Sensor resistance charts  
10 Sensor resistance charts  
Outlet temperature sensor characteristics  
110  
10 5  
10 0  
9 5  
9 0  
8 5  
8 0  
75  
70  
6 5  
6 0  
55  
50  
4 5  
4 0  
3 5  
3 0  
2 5  
2 0  
15  
2 2 2  
2 17  
2 12  
2 0 7  
2 0 2  
19 7  
19 2  
18 7  
18 2  
177  
172  
16 7  
16 2  
157  
152  
14 7  
14 2  
13 7  
13 2  
12 7  
12 2  
117  
112  
10 7  
10 2  
9 7  
9 2  
8 7  
8 2  
77  
72  
6 7  
6 2  
57  
52  
10  
4 7  
4 2  
3 7  
3 2  
5
0
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37  
Resistance (Kohm)  
Fig. 60  
Inlet temperature sensor characteristics  
12 0  
2 4 7  
2 4 2  
115  
110  
10 5  
10 0  
9 5  
9 0  
8 5  
8 0  
75  
70  
6 5  
6 0  
55  
50  
4 5  
4 0  
3 5  
3 0  
2 5  
2 0  
15  
2 3 7  
2 3 2  
2 2 7  
2 2 2  
2 17  
2 12  
2 0 7  
2 0 2  
19 7  
19 2  
18 7  
18 2  
177  
172  
16 7  
16 2  
157  
152  
14 7  
14 2  
13 7  
13 2  
12 7  
12 2  
117  
112  
10 7  
10 2  
9 7  
9 2  
8 7  
8 2  
77  
72  
6 7  
6 2  
57  
52  
4 7  
4 2  
3 7  
3 2  
10  
5
0
0
1
2
3
4
5
6
7
8
9
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
Resistance (Kohm)  
Fig. 61  
46  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Sensor resistance charts  
Back Flow characteristics  
155  
150  
14 5  
14 0  
13 5  
13 0  
12 5  
12 0  
302  
297  
292  
287  
282  
277  
272  
267  
262  
257  
252  
247  
242  
237  
232  
227  
222  
217  
212  
207  
202  
197  
192  
187  
182  
177  
172  
167  
162  
157  
152  
147  
142  
137  
132  
127  
122  
117  
112  
107  
102  
97  
115  
110  
10 5  
10 0  
9 5  
9 0  
8 5  
8 0  
75  
70  
6 5  
6 0  
55  
50  
4 5  
4 0  
3 5  
3 0  
2 5  
2 0  
15  
92  
87  
82  
77  
72  
67  
62  
57  
52  
47  
42  
37  
32  
10  
5
0
0
1
2
3
4
5
6
7
8
9
10  
11  
12  
13  
14  
15 16  
17  
18  
19 20  
21 22 23 24 25 26 27 28 29 30  
31 32 33 34 35 36 37  
Resistance (Kohm)  
Fig. 62  
47  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
GWH 2700 ES Functional scheme  
11 GWH 2700 ES Functional scheme  
Fig. 63 Functional scheme  
48  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12 Interior components diagram and parts list  
12.1 Interior components  
Fig. 64 Components  
1
Flue gas collector  
Heat exchanger  
Flame sensor  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
Ignition electrodes  
Observation window  
2
3
Backflow temperature sensor  
Secondary air fan  
4
Primary fan (Mixer)  
Outlet temperature sensor  
LCD display  
5
Gas valve  
Water valve with engine and temperature sensor  
6
7
On/Off button  
Reset button  
Control unit  
Up button  
Down button  
LED  
8
9
Program key  
Flue gas limiter  
Heat exchanger overheat sensor (ECO)  
10  
11  
49  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
Fig. 65 Appliance overview  
50  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12.2 Components diagram  
12.2.1 Group 1  
9
16  
9
15  
12  
9
17  
15  
13  
14  
10  
5
6
8
9
7
3
11  
4
2
1
6720902973.AA JF  
Fig. 66 Components Diagram  
Item  
10  
Description  
Reference  
Item  
Description  
Front cover  
Reference  
8 705 431 286  
8 705 506 862  
8 701 103 140  
8 703 401 170  
8 700 506 300  
8 704 701 084  
8 705 600 003  
8 708 104 103  
8 703 403 012  
Combustion cover clip  
Grommet set  
8 701 201 032  
8 710 203 039  
8 705 504 162  
8 700 103 710  
8 708 006 022  
8 700 103 166  
8 705 504 116  
8 701 309 164  
1
2
3
4
5
6
7
8
9
11  
Cover shield  
12  
Exhaust accessory  
Gasket exhaust  
Inlet air cover  
Trade mark badge  
Cover screw  
13  
14  
Combustion cover  
Combustion cover gasket  
Observation window  
Holding bracket  
Screw  
15  
Inlet air gasket  
16  
Inlet air accessory  
Mounting bracket  
17  
Table 21  
Table 21  
51  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12.2.2 Group 2  
3
2
1
5
4
8
9
6
7
6720902974.AA JF  
Fig. 67 Components Diagram  
Item  
Description  
Site window  
Reference  
Item  
Description  
Reference  
8 705 406 422  
8 704 701 052  
8 705 700 153  
8 707 206 204  
8 704 701 054  
6
7
8
9
8 701 000 401  
8 701 302 249  
8 700 205 147  
8 710 303 027  
1
2
3
4
5
Heat exchanger  
Ignition group  
Heat exchanger top gasket  
Flue gas collector  
Heat exchanger O-ring  
Rubber grommet  
Overheat sensor (ECO)  
Heat exchanger bottom gasket  
Table 22  
Table 22  
52  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12.2.3 Group 3  
5
1
2
4
3
6
9
16  
13  
8
12  
11  
7
15  
14  
17  
6720902975.AA JF  
Fig. 68 Components Diagram  
Item Description  
Reference  
Item Description  
Reference  
8 708 120 699  
8 704 701 087  
8 707 204 071  
8 707 206 459  
8 704 701 097  
2 915 011 006  
8 707 204 094  
8 707 204 072  
8 703 403 012  
8 705 700 170  
10  
11  
12  
13  
14  
15  
16  
17  
Air duct O-ring  
Venturi  
8 700 205 149  
8 700 306 226  
8 700 205 224  
8 704 701 059  
2 910 642 150  
8 701 004 049  
8 705 700 155  
2 910 952 122  
1
2
3
4
5
6
7
7
8
9
Main burner  
Burner gasket  
Primary fan  
O-ring  
Mixer / Fan gasket  
Screw  
Backflow temperature sensor  
Washer  
Plate gasket  
Air supply duct  
Screw  
Fan mount nut  
Secondary fan - NG  
Secondary fan - LPG  
Screw  
Table 23  
Gas / Air Mixer  
Table 23  
53  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12.2.4 Group 4  
14  
11  
10  
13  
12  
11  
6
7
9
1
8
5
2
3
4
6720608158-73.1AL  
Fig. 69 Components Diagram  
Item  
8
Description  
Reference  
Item  
Description  
Gas valve  
Reference  
8 707 021 019  
8 703 404 219  
8 700 203 041  
8 700 703 136  
8 703 300 041  
8 700 715 389  
8 700 103 014  
Gas filter  
8 700 507 002  
8 704 701 085  
8 705 202 140  
8 704 701 062  
8 703 404 220  
8 700 205 009  
2 910 149 181  
1
2
3
4
5
6
7
9
Gasket  
Pressure tapping  
Washer  
10  
11  
12  
13  
14  
Gas / Fan connector  
Washer  
Pressure balance tube  
Pressure balance nut  
Gas supply pipe  
Gas valve washer  
Regulation screw  
O-ring  
Screw  
Table 24  
Table 24  
54  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12.2.5 Group 5  
Fig. 70 Components Diagram  
Item Description  
Reference  
Item Description  
Reference  
8 708 505 024  
8 700 205 147  
8 700 715 394  
8 701 201 028  
8 700 715 469  
8 700 400 015  
8 703 305 349  
8 710 103 045  
8 701 300 025  
10  
Inlet fitting with filter  
8 703 305 356  
1
2
3
4
5
6
7
8
9
Water valve with engine  
O-ring  
11  
12  
13  
14  
15  
O-ring  
8 700 205 157  
8 716 102 607  
8 700 507 059  
8 700 103 764  
8 700 205 231  
Cold water pipe  
Pipe connection clip  
Hot water pipe  
Watervalve clip  
Water filter  
Washer  
Temperature sensor  
Outlet fitting  
O-ring  
Table 25  
Inlet / Outlet washer  
Wireform spring  
Table 25  
55  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Interior components diagram and parts list  
12.2.6 Group 6  
4
8
5
6
7
9
10  
11  
3
2
1
14  
15  
16  
12  
13  
6720902978.AA JF  
Fig. 71 Components Diagram  
Item Description  
Reference  
Item Description  
Reference  
8 707 207 257  
1 904 521 342  
8 700 609 008  
8 704 401 371  
8 704 401 378  
8 704 401 347  
8 704 401 348  
8 704 401 376  
9
Electrode cables  
Flue gas limiter  
8 704 401 346  
8 700 400 032  
7 709 003 617  
7 709 003 665  
8 707 207 153  
8 700 201 012  
8 703 401 109  
8 708 300 123  
1
2
3
4
5
6
7
8
Control unit  
10  
11  
12  
13  
14  
15  
16  
Fuse T2.5A  
Cascading kit (optional)  
Anti freeze kit  
Fuse T1.6A  
Power supply cables  
Power supply cord  
Fan cables  
Remote control (optional)  
Shaped seal (optional)  
Screw (optional)  
Wire harness  
Jumper  
Printed circuit transceiver (optional)  
Table 26  
Table 26  
56  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Protecting the environment  
13 Protecting the environment  
Packing  
The packing box may be fully recycled as confirmed by  
the recycling symbol  
.
Components  
Many parts in the heater can be fully recycled in the end  
of the product life. Contact your city authorities for  
information about the disposal of recyclable products.  
57  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Limited Warranty  
14 Limited Warranty  
General  
Service Labor Costs  
Aquastar water heaters are warranted by the  
Manufacturer  
Thermotechnology Corp..  
This warranty does not cover any labor costs  
associated with service, removal or re-installation of  
part(s). All such costs must be borne by the Purchaser.  
Additionally, this warranty does not cover any labor  
costs associated with service, removal, installation or  
re-installation of the original water heater or a replaced  
water heater.  
(BOSCH)  
through  
Bosch  
Bosch thermotechnology corporation will furnish a  
replacement heat exchanger and will furnish a  
replacement of any other part which fails in normal use  
and service within the applicable periods specified  
below, in accordance with the terms of this warranty.  
The Bosch Thermotechnology Corp. replacement will  
be warranted for the unexpired portion of the original  
warranty. This warranty will be valid only for water  
heaters in possession of the original purchaser as  
recorded on the warranty card.  
NOTE: the water heater must be free of  
damaging scale deposits and not subject  
i
to gas pressures greater than those  
shown on the rating plate, which must not  
be altered, defaced or removed.  
The Heat Exchanger  
How to Make a Claim  
If the heat exchanger fails within twelve (12) years after  
the original installation and operation, Bosch  
Thermotechnology Corp. will furnish a replacement  
heat exchanger. However, if the water heater is used  
within an approved hot water recirculation and supplied  
with circulated water, this heat exchanger warranty is  
limited to three (3) years from date of original installation  
and operation. If the water heater is installed in other  
than a single family dwelling, this heat exchanger  
warranty is limited to two (2) years from date of original  
installation and operation.  
Any claim for warranty parts should be made to your  
local dealer or distributor:  
BOSCH THERMOTECHNOLOGY CORP.  
340 Mad River Park  
Waitsfield, VT 05673  
TEL. 800-642-3111  
In most cases, the dealer or distributor will be able to  
promptly honor your claim and subsequently notify  
Bosch Thermotechnology Corp.. However, all  
replacements are made subject to validation by Bosch  
Thermotechnology Corp. of in-warranty coverage. The  
damaged or defective item must be made available in  
exchange for the replacement.  
Exceptions  
This warranty will not apply:  
1. to defects or malfunctions resulting from failure to  
properly install, operate or maintain the unit in  
accordance with the printed instructions provided;  
Miscellaneous  
2. to damage or abuse, accident, neglect or freezing  
and other acts of nature;  
No one is authorized to make any other warranties on  
behalf of Bosch Thermotechnology Corp.. It is  
expressly understood that the replacement warranty of  
Bosch Thermotechnology Corp. shall be in lieu of any  
and all other warranties, express or implied, including  
warranties of merchantability or fitness for a particular  
use or purpose, and further that Bosch  
Thermotechnology Corp. shall not be liable for any loss  
or damage directly or indirectly arising from the use of  
the hot water heater, or for any consequential damages  
arising from such use (including damages from water  
leakage). Bosch Thermotechnology Corp. sole liability  
with respect to any defect shall be for the replacement  
of the defective part(s). Some states do not allow such  
limitations and exclusions, so the above may not apply  
to you.  
3. to damage resulting from operation with either the  
flame sensor rod or overheat sensor removed;  
4. to failure of the heat exchanger resulting from the  
operation of the water heater in a corrosive  
atmosphere or at water temperatures exceeding the  
maximum rating, or if the water heater is not supplied  
with potable water;  
5. to defects or damage cause by any attachment  
or modification, including any energy-saving device.  
6. to damage resulting from scale deposits and/or  
highly mineralized / unsoftened water supply.  
All Other Parts  
If any other part fails within five (5) years after original  
installation and operation, Bosch Thermotechnology  
Corp. will furnish a replacement part free of charge.  
This warranty gives specific legal rights. You may also  
have other rights which vary from state to state.  
58  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Limited Warranty  
59  
6 720 608 542  
Download from Www.Somanuals.com. All Manuals Search And Download.  
6720608542  
Installer Checklist to be completed by installer upon installation  
Serial Number  
___ ___ ___ ___ ___ ___ ___ ___  
(8 digit serial number is located on rating plate on right side panel)  
Gas Pressure Reading*  
Building Water Pressure  
Installing Company  
Installer name  
Static__________  
__________  
Operating__________  
Range if on Well system __________  
_____________________________________________  
_____________________________________________  
_____________________________________________  
_____________________________________________  
Address  
Phone  
* See Chapter 3.12, page 27 and gas pressure table (to be filled out by installer)  
Installation manual should be left with the owner after the installation is tested and completed  
Replacement Parts available from:  
BOSCH THERMOTECHNOLOGY CORP.  
50 Wentworth Avenue  
Bosch Termotecnologia SA  
Londonderry, NH 03053  
Estrada de Cacia  
Tel. 866-330-2730  
3801 - 856 Aveiro - PORTUGAL  
© 2009 Bosch Thermotechnology Corp.,  
Londonderry, NH all rights reserved  
Download from Www.Somanuals.com. All Manuals Search And Download.  

Black Decker Coffeemaker ODC425 User Manual
Bolens Lawn Mower 130 527 000 User Manual
Breville Rice Cooker BRC520 User Manual
Briggs Stratton Lawn Mower S175X User Manual
Briggs Stratton Pressure Washer 20362 User Manual
Cabletron Systems Network Card EMM E6 Ethernet User Manual
Canon Photo Printer CP220 User Manual
Canon Printer B540 User Manual
Chief Manufacturing Indoor Furnishings LCD2TS User Manual
Cisco Systems IP Phone 86 User Manual