Thermo Products Furnace CBD1 100N User Manual
CONDENSING GAS FURNACE  
INSTALLATION AND OPERATION MANUAL  
MODELS:  
CHB1-50N  
CHB1-75N  
CHB1-100N  
CHB1-125N  
CDB1-50N  
CDB1-75N  
CDB1-100N  
CDB1-125N  
: IF YOU DO NOT FOLLOW THE SAFETY PRECAUTIONS BELOW AND IN THIS MANUAL, A  
FIRE OR EXPLOSION MAY RESULT CAUSING PROPERTY DAMAGE, PERSONAL INJURY, OR LOSS OF  
LIFE.  
DO NOT STORE OR USE GASOLINE OR OTHER FLAMMABLE VAPORS AND LIQUIDS IN THE VICINITY OF  
THIS OR ANY OTHER APPLIANCE.  
WHAT TO DO IF YOU SMELL GAS:  
•
•
•
•
DO NOT TRY TO LIGHT ANY APPLIANCE.  
DO NOT TOUCH ANY ELECTRICAL SWITCH; DO NOT USE ANY PHONE IN YOUR BUILDING.  
LEAVE THE BUILDING IMMEDIATELY.  
IMMEDIATELY CALL YOUR GAS SUPPLIER FROM A NEIGHBOR’S PHONE. FOLLOW THE GAS  
SUPPLIER’S INSTRUCTIONS.  
•
IF YOU CANNOT REACH YOUR GAS SUPPLIER; CALL THE FIRE DEPARTMENT.  
INSTALLATION AND SERVICE MUST BE PERFORMED BY A QUALIFIED INSTALLER, SERVICE AGENCY OR  
THE GAS SUPPLIER. (REFERRED TO IN THESE INSTRUCTIONS AS  
CONTRACTOR).  
A
QUALIFIED HEATING  
PLEASE READ THESE INSTRUCTIONS PRIOR TO INSTALLATION, INITIAL FIRING, AND BEFORE  
PERFORMING ANY SERVICE OR MAINTENANCE. THESE INSTRUCTIONS MUST BE LEFT WITH THE  
HOMEOWNER AND SHOULD BE RETAINED FOR FUTURE REFERENCE BY QUALIFIED SERVICE  
PERSONNEL.  
THERMO PRODUCTS, LLC.  
BOX 217  
NORTH JUDSON, IN 46366  
PHONE: (574) 896-2133  
MADE IN USA  
MG-1006  
ECN 5355-MA 140303  
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All installations and services must be performed by qualified service personnel.  
This and the previous page contain reproductions of the various warning and instruction labels  
placed on the Thermo Pride Condensing Gas Furnaces. Please read and comply with the contents  
of these labels.  
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 does not have a pilot. It is equipped with a hot  
surface igniter that automatically lights the burner. Do not try to  
light the burner by hand.  
B. BEFORE OPERATING smell all around the appliance area for gas.  
Be sure to smell next to the base of unit because some gas is  
heavier than air and will settle on the floor or ground.  
WHAT TO DO IF YOU SMELL GAS  
?
?
Do not try to light any appliance.  
Do not touch any electric switch; do not use any phone in your  
building.  
?
?
Immediately call your gas supplier from a neighbor's phone.  
Follow the gas supplier's instructions.  
If you cannot reach your gas supplier, call the fire department.  
C. Use only your hand to move the gas control switch. Never use tools.  
If the switch will not move by hand, don't try to repair it, call a  
qualified service technician. Force or attempted repair may result in  
a fire or explosion.  
D. 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.  
1. STOP! Read the safety information above on this label.  
2. Set the thermostat to the lowest setting.  
3. Turn off all electric power to the appliance.  
4. This appliance is equipped with a hot surface igniter that  
automatically lights the burner. Do not try to light the burner by  
hand.  
5. Move the gas control switch to the "OFF" position.  
6. Wait five (5) minutes to clear out any gas. Then smell for gas,  
including near the floor or ground. If you smell gas, STOP! Follow  
"B" in the safety information above on this label. If you don't smell  
gas, go to the next step.  
7. Move the gas control switch to the "ON" position.  
8. Turn on all electric power to the appliance.  
9. Set thermostat to desired setting, and, if equipped, set the operating  
mode to "HEAT".  
10.If appliance will not operate, follow the instructions "To Turn Off  
Gas To Appliance" and call your service technician or gas supplier.  
1. Set thermostat to lowest setting, and, if equipped, set the operating  
mode to "COOL" or "OFF".  
2. If service is to be performed, turn off all electric power to the  
appliance.  
3. To turn off gas control valve, remove the burner compartment cover.  
4. Move the gas control switch to the "OFF" position.  
5. Replace the burner compartment cover.  
390540  
ii  
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All installations and services must be performed by qualified service personnel.  
The following safety information should be read, understood, and followed by the installer.  
1. Use only with type of gas approved for this furnace. Refer to furnace rating plate.  
2. Connect this furnace to an approved vent system only. Combustion products must be carried outdoors. Refer to  
Section III, D thru H, of this manual.  
The following pages contain various warnings and cautions found throughout the Thermo Pride Highboy and  
Dual Poise Condensing Gas Furnace Manual. Please read and comply with the statements below.  
: This furnace is not to be used for temporary heating of buildings or structures under construction.  
: These high efficiency condensing furnaces are not certified for and shall not be vented into a  
standard or any type of chimney.  
: These furnaces may not be common vented with any other appliance.  
: The vent and air intake elbows must be kept away from bushes, shrubs or any vegetation that may  
restrict the flow of flue products. It must also be kept clear of any leaves, weeds or other combustible materials.  
Keep the vent hood clear of snow. Avoid locating the terminals in areas where standing water or condensate  
drippage may be a problem.  
: This CHB1/CDB1 furnace has been designed to be installed as a direct vent system. The failure to  
install the vent/air intake system as specified in these instructions will void the heat exchanger warranty and may  
result in property damage, personal injury or loss of life.  
: Outside combustion air must not come from an area that is directly adjacent to a pool, hot tub or  
spa. Measures should be taken to prevent the entry of corrosive chemicals or vapors to the combustion and  
ventilation air supply. Such chemicals include but are not limited to chlorinated and/or fluorinated hydrocarbons  
such as found in refrigerants, aerosol propellants, dry cleaning fluids, degreasers and removers. Other harmful  
compounds may come from bleaches, air fresheners or mastics. Vapors from such products can form acid  
compounds when burned in a gas flame. Should acid compounds form in your furnace; it may reduce the life of  
the furnace.  
: Because of the potential of odorant fade, a gas leak may not be detected by smell. If this furnace  
is installed below grade, contact your gas supplier for a gas detector.  
: Turn off power to furnace before it is placed into service. The gas piping system must have been  
leak tested by a qualified heating contractor.  
: It may be necessary to purge the air out of the gas line for initial start-up of the furnace after  
installation. This should be done by a qualified heating contractor. If excessive gas escapes when purging the  
gas supply at the union, allow the area to ventilate for at least 15 minutes before attempting to start the furnace.  
LP gas is especially dangerous because the specific gravity of LP gas allows it to accumulate at floor level at a  
dangerous concentration. For remainder of operating instructions, reference Users Information Manual.  
: Heat exchanger oil will burn off on initial firing creating an unpleasant odor. To prevent this  
odor from occurring more than once, it is suggested that:  
1. A window(s) be opened.  
2. The thermostat set at highest setting.  
3. The furnace remain running at conditions 1&2 for 30 minutes or until odor has dissipated.  
iii  
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All installations and services must be performed by qualified service personnel.  
: The CHB1/CDB1 furnace models are sealed combustion design, which does not require an air  
shutter adjustment (air shutters are not used) for proper flame characteristics. Burner box access cover must  
always be secured with all screws in place and tightened before operating furnace.  
: Personal injury or property damage could result from repair or service of this furnace by anyone  
other than a qualified heating contractor. Only the homeowner/user routine maintenance described in the Users  
Information Manual may be performed by the user.  
iv  
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INDEX  
SECTION  
BEGINNING PAGE  
I.  
SAFETY INFORMATION  
i
II.  
III.  
FURNACE SPECIFICATIONS  
GENERAL INSTALLATION  
1
5
A. CODES AND CLEARANCES  
5
B. FURNACE LOCATION  
6
B1.CDB1 HORIZONTAL APPLICATION  
C. REPLACING EXISTING FURNACE FROM A COMMON VENT  
D. GENERAL REQUIREMENTS FOR VENTING CHB1/CDB1  
E. SIDEWALL VENTING  
E1. SINGLE PIPE (SIDEWALL) VENTING OPTION  
F. INSTALLATION OF OUTSIDE VENT/AIR INTAKE TERMS.  
G. CONNECTING FURNACE TO ROOF VENT/AIR TERMS.  
H. CONNECTING FURNACE TO VENT/AIR INTAKE TERMS.  
I. CONDENSATE DRAIN LINE & TRAP ASSY.  
J. GENERAL GAS PIPING  
J1. REQUIREMENTS & SIZING OF DUCTWORK  
K. FILTERS  
L. WIRING  
STARTING THE UNIT  
A. SEQUENCE OF OPERATIONS  
7
8
9
11  
14  
14  
16  
17  
22  
25  
26  
29  
31  
34  
34  
36  
36  
37  
38  
39  
40  
IV.  
B. INITIAL START-UP  
C. ADJUSTMENT OF BTU INPUT RATE  
D. BURNER ADJUSTMENT  
E. FURNACE CHECKOUT PROCEDURE  
INSTALLER’S INSTRUCTIONS TO USER  
TROUBLESHOOTING  
VI.  
VII.  
APPENDIX – A  
APPENDIX – B  
REPLACEMENT PARTS LIST  
WIRING DIAGRAMS  
46  
50  
v
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II. FURNACE SPECIFICATIONS  
CHB1 SERIES  
MODEL NO.  
BTU/HR INPUT  
BTU/HR OUTPUT  
CHB1-50  
50,000  
47,000  
CHB1-75  
75,000  
72,000  
CHB1-100  
100,000  
94,000  
CHB1-125  
125,000  
116,000  
HT. OF CASING  
44-1/4”  
17”  
27-1/2”  
15 x 18  
25 x 16  
44-1/4”  
17”  
27-1/2”  
15 x 18  
25 x 16  
44-1/4”  
21”  
27-1/2”  
19 x 18  
25 x 16  
44-1/4”  
24”  
27-1/2”  
22 x 18  
25 x 16  
WIDTH OF CASING  
DEPTH OF CASING  
WARM AIR OUTLET  
RETURN AIR INLET  
DIA. OF FLUE  
DIA. OF COMBUSTION  
AIR INTAKE  
2”  
2”  
2”  
2”  
3”  
3”  
3”  
3”  
CFM @ .2” & .5” w.c.  
EXTERNAL STATIC PRESSURE  
.2” .5”  
.2” .5”  
.2” .5”  
.2” .5”  
@HI SPEED  
@MH SPEED  
@ML SPEED  
@LO SPEED  
1100 860  
1000 720  
1600 1380  
1250 1150  
1030 930  
820 700  
1940 1700  
1720 1540  
1530 1380  
1340 1220  
2770 2060  
1800 1700  
1730 1600  
1670 1550  
--  
--  
610 420  
TEMPERATURE RISE  
BLOWER MOTOR HP  
NO. OF SPEEDS  
70  
.20  
3
70  
.41  
4
70  
.50  
4
70  
.75  
4
RUN CAPACITOR  
10 mfd  
10 mfd  
10 mfd  
10 mfd  
LARGEST RECOMMEDED  
AIR CONDITIONER  
SIZE OF FILTERS  
2 Ton  
3.5 Ton  
4 Ton  
5 Ton  
24-3/4” x 15-3/4”  
24-3/4” x 15-3/4”  
24-3/4” x 15-3/4” 24-3/4” x 19-3/4”  
NOTES:  
1. BTU output based on annual fuel utilization efficiency rated by manufacturer.  
2. On all outlet and inlet dimensions, the first dimension is width.  
3. To permit largest recommended air conditioning (at .5 static pressure), selection of the highest motor speed is  
required.  
1
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CDB1 SERIES  
MODEL NO.  
BTU/HR INPUT  
BTU/HR OUTPUT  
CDB1-50  
50,000  
47,000  
CDB1-75  
75,000  
70,000  
CDB1-100  
100,000  
94,000  
CDB1-125  
125,000  
116,000  
HT. OF CASING  
46-1/4”  
17”  
27-1/2”  
15 x 18  
15 x 22  
46-1/4”  
17”  
27-1/2”  
15 x 18  
15 x 22  
46-1/4”  
21”  
27-1/2”  
19 x 18  
19 x 22  
46-1/4”  
24”  
27-1/2”  
22 x 18  
22 x 22  
WIDTH OF CASING  
DEPTH OF CASING  
WARM AIR OUTLET  
RETURN AIR INLET  
DIA. OF FLUE  
DIA. OF COMBUSTION  
AIR INTAKE  
2”  
2”  
2”  
2”  
3”  
3”  
3”  
3”  
CFM @ .2” & .5” w.c.  
EXTERNAL STATIC PRESSURE  
.2” .5”  
.2” .5”  
.2” .5”  
.2” .5”  
@HI SPEED  
@MH SPEED  
@ML SPEED  
@LO SPEED  
1120 930  
1000 750  
1530 1340  
1270 1110  
1050 930  
850 720  
1830 1590  
1660 1460  
1520 1340  
1370 1230  
2280 2010  
1830 1650  
1750 1570  
1660 1530  
--  
--  
616 420  
TEMPERATURE RISE  
BLOWER MOTOR HP  
NO. OF SPEEDS  
70  
.20  
3
70  
.41  
4
70  
.50  
4
70  
.75  
4
RUN CAPACITOR  
LARGEST RECOMMEDED  
AIR CONDITIONER  
SIZE OF FILTERS  
NOTES:  
10 mfd  
10 mfd  
10 mfd  
15 mfd  
2 Ton  
3.5 Ton  
4 Ton  
5 Ton  
21-3/4” x 14”(2)  
21-3/4” x 14”(2)  
21-3/4” x 14”(2)  
21-3/4” x 14”(2)  
1. BTU output based on annual fuel utilization efficiency rated by manufacturer.  
2. On all outlet and inlet dimensions, the first dimension is width.  
3. To permit largest recommended air conditioning (at .5 static pressure), selection of the highest motor speed is  
required.  
4. Electrical characteristics at 115 volts, 60 Hz., 1 phase (less than 15 amps. for all models).  
5. All specifications are subject to change without notice.  
2
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INSTALLATION PARTS PACKAGES - CHB1-50/75  
PARTS PACKAGE  
DESCRIPTION  
PART #  
QUANTITY  
#S00S4405/4406  
2-3/8” ID radiator hose  
Thermostat lead bushing  
PVC trap assembly  
410017  
350750  
320816  
1
1
1
#8 x ¾ coated TEK screws for  
mounting trap & inlet/outlet collars  
11/16” OD x 1/2” ID vinyl tubing  
2 x 4 electrical J-box  
2 x 4 electrical J-box cover  
#8 x ½ TEK screws for  
mounting 2 x 4 J-box  
300283  
4
410060  
350024  
350020  
24”  
1
1
300208  
2
#10-32 x ½ green ground screw  
#10-32 hex nut  
3/16” dia. star washer  
Grounding instructions  
Wire nut  
3” stainless steel hose clamp  
J-box wire bushing  
Drain hose grommet  
300109  
300110  
300270  
MG-966  
300132  
300276  
350016  
350446  
300299  
MG-987  
320818  
320833  
1
1
1
1
2
2
1
1
3
1
1
1
Spring clamp, 11/16”  
Installation notice  
PVC tee assembly, 2” dia.  
CPVC XPVC adapter  
Gas Conversion Kit  
AOPS7677/7678  
1
INSTALLATION PARTS PACKAGES - CHB1-100/125  
PARTS PACKAGE  
DESCRIPTION  
#S00S4407/4408  
PART #  
QUANTITY  
2-3/8” ID radiator hose  
Thermostat lead bushing  
PVC trap assembly  
410017  
350750  
320816  
1
1
1
#8 x ¾ coated TEK screws for  
mounting trap & inlet/outlet collars  
11/16” OD x 1/2” ID vinyl tubing  
2 x 4 electrical J-box  
2 x 4 electrical J-box cover  
#8 x ½ TEK screws for  
mounting 2 x 4 J-box  
300283  
4
410060  
350024  
350020  
24”  
1
1
300208  
2
#10-32 x ½ green ground screw  
#10-32 hex nut  
3/16” dia. star washer  
Grounding instructions  
Wire nut  
3” stainless steel hose clamp  
J-box wire bushing  
300109  
300110  
300270  
MG-966  
300132  
300276  
350016  
1
1
1
1
2
2
1
3
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Drain hose grommet  
Spring clamp, 11/16”  
Installation notice  
350446  
300299  
MG-987  
1
3
1
PVC tee assembly, 2 x 3” dia.  
CPVC XPVC adapter  
Gas Conversion Kit  
320817  
320833  
AOPS7679/7664  
1
1
1
INSTALLATION PARTS PACKAGES - CDB1-50/75  
PARTS PACKAGE  
DESCRIPTION  
#S00S4409/4410  
PART #  
QUANTITY  
2-3/8” ID radiator hose  
Thermostat lead bushing  
PVC trap assembly  
410017  
350750  
320816  
1
1
1
#8 x ¾ coated TEK screws for  
mounting trap & inlet/outlet collars  
11/16” OD x 1/2” ID vinyl tubing  
2 x 4 electrical J-box  
2 x 4 electrical J-box cover  
#8 x ½ TEK screws for  
mounting 2 x 4 J-box  
#10-32 x ½ green ground screw  
#10-32 hex nut  
3/16” dia. star washer  
Grounding instructions  
Wire nut  
3” stainless steel hose clamp  
J-box wire bushing  
Drain hose grommet  
Spring clamp, 11/16”  
Installation notice  
PVC tee assembly, 2” dia.  
Pipe 2” dia. PVC 15”  
Bracket  
300283  
6
410060  
350024  
350020  
24”  
1
1
300208  
2
300109  
300110  
300270  
MG-966  
300132  
300276  
350016  
350446  
300299  
MG-987  
320819  
14401  
1
1
1
1
2
2
1
1
3
1
1
1
1
14406  
CPVC XPVC adapter  
Gas Conversion Kit  
320833  
1
1
AOPS7677/7678  
INSTALLATION PARTS PACKAGES - CDB1-100/125  
PARTS PACKAGE  
DESCRIPTION  
#S00S4411/4412  
PART #  
QUANTITY  
2-3/8” ID radiator hose  
Thermostat lead bushing  
PVC trap assembly  
410017  
350750  
320816  
1
1
1
#8 x ¾ coated TEK screws for  
mounting trap & inlet/outlet collars  
11/16” OD x 1/2” ID vinyl tubing  
2 x 4 electrical J-box  
300283  
4
410060  
350024  
350020  
24”  
1
1
2 x 4 electrical J-box cover  
4
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#8 x ½ TEK screws for  
300208  
2
mounting 2 x 4 J-box  
#10-32 x ½ green ground screw  
#10-32 hex nut  
3/16” dia. star washer  
Grounding instructions  
Wire nut  
3” stainless steel hose clamp  
J-box wire bushing  
Drain hose grommet  
Spring clamp, 11/16”  
Installation notice  
300109  
300110  
300270  
MG-966  
300132  
300276  
350016  
350446  
300299  
MG-987  
320817  
320819  
14401  
1
1
1
1
2
2
1
1
3
1
1
1
1
1
1
PVC tee assembly, 2 x 3” dia.  
PVC tee assembly, 2” dia.  
Pipe 2” dia. PVC 15”  
Bracket  
14406  
320067  
Reducer 2” x 3” PVC  
CPVC XPVC adapter  
320833  
1
Gas Conversion Kit  
AOPS7679/7664  
1
III. GENERAL INSTALLATION  
This furnace is equipped with orifices size for operation with natural gas. For conversion to Propane Gas see  
instruction in Gas Conversion Section of this manual.  
These Category Type IV furnaces are shipped completely assembled and wired (internally). See the Dealer  
Receiving and Freight Claim Procedure Section of the price guide for parts shortage or damage. The furnace and  
duct system must be adjusted to obtain a temperature rise of 55°F to 85°F (35°F to 65°F CHB1-75) through the  
furnace after installation. (See rating label located on side panel inside the furnace vestibule). The installation must  
conform with local codes, or in the absence of local codes, with the National Fuel Gas Codes (ANSI Z223.1 or latest  
edition) and with these instructions.  
: This furnace is not to be used for temporary heating of buildings or structures under construction.  
Many of the chemicals used during construction, when burned, form acid bearing condensate that can substantially  
reduce the life of the heat exchanger.  
It is recommended that a commercially available CO alarm be installed in conjunction with any fossil fuel burning  
appliance. The CO alarm shall be installed according to the alarm manufacturer’s installation instructions and be  
listed in accordance with the latest edition of the UL Standard for Single and Multiple Station Carbon Monoxide  
Alarms, UL 2034, or the CSA International Standard, Residential Carbon Monoxide Alarming Devises, CSA 6.19.  
A. CODES AND CLEARANCES  
The following items must be considered when choosing the size and location of the furnace.  
1. All local codes and/or regulations take precedence over the instructions in this manual and should be followed  
accordingly. In the absence of local codes, installation must conform with these instructions, regulations of the  
National Fire Protection Association, provisions of National Electrical Code (ANSI/NFPA70 or latest edition),  
and the National Fuel Gas Code (ANSI Z223.1 or latest edition).  
5
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2. The BTU output capacity of the furnace proposed for installation should be based on a heat loss calculation  
made according to the manuals provided by the Air Conditioning Contractors of America (ACCA) or ASHRAE.  
3. MINIMUM CLEARANCES TO COMBUSTIBLE MATERIALS  
TABLE 1  
FROM SIDES OF  
FURNACE & REAR  
TOP OF  
PLENUM  
0 IN.  
FROM THE  
FLUE OR VENT  
0 IN.  
SIDE OF  
PLENUM  
1 IN.  
MODEL NO.  
FRONT  
CHB1-50  
CHB1-75  
CHB1-100  
CHB1-125  
CDB1-50  
CDB1-75  
CDB1-100  
CDB1-125  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
6 IN.  
6 IN.  
6 IN.  
6 IN.  
6 IN.  
6 IN.  
6 IN.  
6 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
0 IN.  
1 IN.  
1 IN.  
1 IN.  
1 IN.  
1 IN.  
1 IN.  
1 IN.  
The CHB1-50, 75, 100 and 125 furnaces may be installed on combustible flooring. The furnace shall not be installed  
directly on carpeting, tile or other combustible material other than wood flooring.  
The CDB1-50, 75, 100 and 125 furnaces are to be installed on non-combustible flooring only. The non-combustible  
floor bases model no. 50 DA base for CDB1- (50,75) model no. 100 CA base for the model no. CDB1-100 and  
model no. 125 CA base for CDB1-125 are available for the counterflow furnaces to allow their installations on  
combustible flooring.  
These furnaces may be installed in an alcove or in a closet if the minimum clearances to combustible construction  
(listed previously) are met. The CDB1 series furnaces may be installed in an attic or crawl space. Refer to section III,  
B1 of this installation manual.  
The minimum clearances are listed for fire protection. Clearance for servicing the front of the furnaces and to all  
points on the furnace requiring access must be 24”*.  
*For horizontal furnace installation, refer to section III, B1 of this installation manual.  
Equipment must be installed in accordance with regulations of the National Board of Fire Underwriters.  
Authorities having jurisdiction should be consulted before installations are made.  
B. FURNACE LOCATION  
: These high efficiency condensing furnaces are not certified for and shall not be vented into a  
standard or any type of chimney.  
The following shall be considered for locating the furnace:  
1. For best performance locate the furnace so that it is centralized with respect to the duct system and as near as  
possible to a floor drain since condensate drainage must be provided.  
2. Place the unit so that proper venting can be achieved, with a minimum number of elbows, in accord with the  
instructions in this manual.  
3. The furnace must be located on a level, dry surface. The furnace must be installed so that the electrical  
components are protected from water. If the area becomes wet or damp at times, the furnace should be raised  
above the floor using a concrete base, bricks, patio blocks, etc.  
NOTICE: Ensure furnace is level after installation to ensure proper drainage and operation.  
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4. This furnace must be connected to a drain in accordance with these instructions. If it is not practical to connect  
the unit to a drain, a condensate pump must be used and can be ordered as an accessory, part number 350225. If  
an acid neutralizer kit is required by local code or the customer, it is available under part number 320095.  
B1. CDB1 HORIZONTAL APPLICATION  
The CDB1-50, 75, 100, and 125 furnaces may be installed in a horizontal position by placing the furnace on the left  
or right side (as viewed from the front in the upright position).  
For left or right horizontal applications of the CDB1 series units, the rollout switch located on the burner box must  
be moved to the pre-punched mounting holes on the side of the burner box. Screws are provided in pre-punched  
holes at the required limit location. Remove these screws and use them to mount the limit to new location. Utilize  
previously removed limit mounting screws to fill voided holes at previous limit location (See Figure 1).  
For a right side horizontal application of the CDB1 series units, the hose from the single tap pressure switch (top  
switch) is already connected correctly (See Figure 1).  
For a left side horizontal application of the CDB1 series units, the hose from the single tap pressure switch (bottom  
switch) must be moved to the lower front tap on the face of the collector box. Use the black cap removed from this  
tap to plug the original pressure switch tap.  
NOTE: The hose, when moved, must be shortened (cut) to ensure that no excess hose exists to cause a sag, loop, or  
"water trap".  
For a right side horizontal application of the CDB1 series units, the auxiliary limit switch located on the right side of  
the house air blower must be moved to the bracket on the opposite (left) side of the blower (See Figure 1).  
NOTE: When the CDB1 is installed as horizontal unit, it is imperative that the auxiliary limit switch and bracket be  
located on the upper side of the house air blower; the burner rollout switch located on the burner box be relocated to  
the side of the burner box; and that the hose from the single tap pressure switch be connected to the lower tap on the  
front of the collector box (See Figure 1).  
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Figure 1  
The horizontal furnace installation should be on a service platform large enough to allow for proper clearances on all  
sides and service access to the front of the furnace (See Table 1). If the furnace is suspended, it must be supported at  
both ends and in the middle with clearance allowed for removal of both access doors. Gas supply line contact is only  
permissible between lines formed by the intersection of the top and two sides of the furnaces casing and the building  
joists, studs, or framing (See Figure 1).  
Equipment must be installed in accordance with regulations of the National Board of Fire Underwriters and  
the National Fuel Gas Code. Authorities having jurisdiction should be consulted before installations are  
made.  
C. Replacing An Existing Furnace From A Common Vent  
: These furnaces may NOT be common vented with any other appliance.  
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D. General Requirements For Venting Models CHB1 / CDB1  
The CHB1 / CDB1 furnace venting system must be installed by a qualified service person in accordance with local  
installation codes and these instructions. In the absence of applicable local codes, conform to the National Fuel Gas  
Code, NFPA 54 /ANSI Z223.1-2002, or latest edition thereof.  
Installation shall, at least, conform to the following requirements.  
1. The exhaust vent / combustion air intake terminations specified by Thermo Products, in this manual, shall  
be used.  
2. All plastic pipe and pipefittings sourced to complete the exhaust vent and air intake systems shall be  
constructed of rigid PVC (polyvinyl chloride) thermoplastic. All components shall have a wall  
thickness equivalent to Schedule 40 series materials.  
In addition, all sourced PVC components shall be listed by a nationally recognized testing agency (e.g.  
NSF, UL, etc.) as conforming to one (1) or more of the following design standards.  
PVC Pipe Designation  
Cellular Core  
Design Standard  
ASTM-F891  
DWV (Drain-Waste-Vent)  
Schedule 40  
ASTM-D2665  
ASTM-D1785  
3. The exhaust vent pipe and combustion air pipe shall be at least as large as the exhaust vent / air intake pipe  
specified by Thermo Products. Size reduction is never permissible. The required exhaust vent / air intake  
pipe sizes are:  
•
•
nominal 2-inch diameter IPS, Schedule 40 series, PVC thermoplastic pipe, for models CHB1–50 / –  
75 & CDB1–50 / –75, or  
nominal 3-inch diameter IPS, Schedule 40 series, PVC thermoplastic pipe, for models CHB1–100 / –  
125 & CDB1–100 / –125.  
4. The furnace model series CHB1 / CDB1 shall not be common vented with any other appliance, including  
those burning solid fuels.  
5. All horizontal runs of exhaust vent pipe shall slope upward at least ¼ inch per foot from the outlet of the  
furnace (for the model series CHB1), or the outlet of the drain tee (for the model series CDB1) to the vent  
termination, beyond the outside wall. This slope will permit proper drainage of the condensate.  
Horizontal runs of air intake pipe shall slope downward at least ¼ inch per foot from the outlet of the last  
elbow or last horizontal run, before exiting the wall, to the intake termination beyond the outside wall. This  
slope will permit proper drainage of any precipitation that enters the intake pipe.  
6. The exhaust vent pipe shall be supported at every joint (no more than 4-feet between supports) to  
prevent pipe blockage due to condensate trapped at a local low point, or sag, in the vent system.  
7. The maximum permissible length of piping (consisting of a combination of straight pipe and a  
corresponding number of elbows) permitted is:  
•
•
75 equivalent feet, for the exhaust vent system, and  
70 equivalent feet, for the combustion air intake system  
8. The maximum quantity of Schedule 40 series, type DWV thermoplastic pipe elbows allowed in each system  
is listed in Table 2. When counting pipe elbows, all elbows used in the exhaust vent or combustion air  
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intake systems must be considered. This includes all elbows, or equivalent pipefittings, used inside the  
furnace jacket in addition to those used to construct the termination. Furthermore, a credit of 5-feet of  
straight pipe may be taken for each elbow, up to maximum of three (3) elbows, which is dropped from the  
maximum permissible number for each system.  
Table 2: Maximum Permissible Exhaust Vent and Combustion Air Intake Lengths When Using the Maximum  
Quantity of Elbows  
Thermoplastic  
Pipe Vent Size  
(Nominal)  
2 in. Diameter IPS  
Exhaust or Maximum Maximu  
3 in. Diameter IPS  
Exhaust or Maximum Maximu  
Furnace Model  
Intake  
Straight  
Pipe  
Qty. of  
m
Qty. of  
Intake  
Straight  
Pipe  
Qty. of  
m
Qty. of  
Exhaust  
Exhaust  
Elbows 1,2 Intake  
Elbows 1, 2 Intake  
Length (ft.)  
Elbows 2  
Length (ft.)  
Elbows 2  
CHB1 / CDB1-50  
CHB1 / CDB1-75  
CHB1 / CDB1-100  
CHB1 / CDB1-125  
35  
8
7
-
-
-
35  
8
7
Not Permitted  
Superscripts:  
1
The drain tee supplied with CHB1 / CDB1 furnace model series is considered equivalent to one (1),  
90° elbow.  
Two (2), 45° elbows can be substituted for one (1), 90° elbow.  
2
Care should be taken to design the shortest possible intake and exhaust systems. Each system should contain  
as few elbows as possible to insure the satisfactory operation of the furnace. However, system length  
should never be less than 8 ft of pipe with two (2), 90 deg. elbows. For best overall operation of the  
combustion system, we recommend the actual equivalent lengths for both the constructed intake and the  
exhaust systems have approximately the same value.  
9. Use a saw designed to cut thermoplastic pipe. All cuts should be made at right angles to the pipe wall.  
Smooth jagged edges and remove all burrs and strings. All pipe joints must utilize standard PVC  
Schedule 40 series, DWV type elbows, couplings, and fittings. Clean all pipe surfaces at connections  
using a fine abrasive material or approved PVC cleaner (primer). Secure all pipe joints using suitable  
permanent PVC pipe solvent cement. Joints are NOT to be made by simply gluing raw edges of butted  
together vent pipe.  
Piping joints inside the furnace vestibule should be sealed with silicone caulk, rather than pipe cement, to  
allow for disassembly and removal of piping, if necessary, during maintenance.  
NOTICE: DO NOT use silicone caulk to seal the pipe sleeve or coupling to the metal air intake collar  
on the burner box. Securing the sleeve or coupling to the collar using a screw is sufficient.  
10. Vent connections shall be checked for leakage with the furnace induced draft blower running and with the  
vent termination blocked. Use a mild soap and water solution to check for leaks.  
11. Vent pipe passing through an unheated space shall be insulated with 1-inch thick, foil-faced fiberglass  
insulation, or equivalent, to prevent freezing of condensate within the pipe.  
12. No clearance is required from the outer surface of the thermoplastic piping to combustible materials for fire  
hazard prevention.  
13. Thermo Products does not require screens be installed in the exhaust vent and air intake piping. However,  
optional stainless steel screens are available from Thermo Products, should the homeowner request them.  
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NOTICE: The furnace model series CHB1 / CDB1 may be vented either through the sidewall or the roof.  
For sidewall instructions, continue to the following section. For roof venting, refer to Section III G, of this  
manual  
E. Direct Venting Through a Sidewall  
1. Vent and combustion air pipes may pass through a maximum wall thickness of 18 inches. The minimum  
wall thickness is 2 inches. Referring to Figure 2, the maximum distance from the outer wall to the center of  
the elbow is 12 inches.  
Figure 2: Proper Direct Vent Terminations (RH & LH views) and Vent Termination Only w/o  
Outside Combustion Air Intake (RH view)  
NOTICE: If exterior sidewall building materials are subject to degradation from contact with flue gases or  
moisture, a minimum 24-inch diameter shield shall be fabricated from stainless steel or UV-resistant plastic  
sheet. The protective shield shall be installed around the vent pipe on the outside wall.  
2. The exhaust vent termination elbow shall be installed in accordance with these instructions and any  
applicable local codes. Refer to Figures 2 and 3 for typical examples of proper terminations.  
a. The exhaust vent termination must be installed in the same atmospheric pressure zone (i.e. on the same  
wall) as the air intake termination.  
b. The bottom edge of the vent termination elbow must be installed at least 12-inches above the outlet of  
intake termination elbow.  
c. The horizontal distance between the inlet and exhaust terminations should be minimized, when  
possible, and should never exceed 24-inches.  
d. The vent and intake systems should utilize the same numbers of elbows and approximately the same  
length of straight pipe to reach the outside termination.  
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Figure 3: Typical Relative Locations of Direct Vent Terminations When Sidewall Venting  
3. Exhaust Vent Terminal Location Clearance Requirements  
a. The vent terminal shall be located at least 3-feet above any forced air inlet located within 10-feet. Refer  
to Figure 4 for a depiction of the minimum required clearances between vent terminations and building  
features according to the National Fuel Gas Code (NFGC).  
b. The vent terminal shall be at least 12-inches below, 12-inches horizontally from, or 12-inches above,  
any door, window, or gravity air inlet into a building. The bottom of the vent terminal shall be located  
at least 12-inches above grade.  
c. The vent terminal shall not be located:  
•
•
•
over public walkways or over an area where wetting of surfaces by condensate, or water vapor,  
could create a nuisance or hazard,  
near soffit vents, crawl space vents, or other areas where condensate or water vapor could create a  
nuisance, hazard, or cause property damage, and  
where wetting of components by condensate, or water vapor, could be detrimental to the operation  
of pressure regulators, relief valves, or any other equipment.  
d. The vent terminal shall be installed a minimum of 14-inches from any obstruction and 3-feet from an  
inside corner of an L-shaped structure.  
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Figure 4: NFGC Minimum Clearances Between the Vent Terminal and Various Building Features  
4. Vent Terminal Location Guidelines  
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: Bushes, shrubs, or any vegetation that may restrict the flow of flue products must be kept  
away from vent and air intake terminations. Terminations must also be kept clear of any leaves, weeds,  
combustible materials, snow, and ice build-up. Avoid locating the vent terminal over areas where  
dripping of condensate, or small pools of acidic condensate, could create a problem.  
In addition to following any local code requirements, when possible, utilize the guidelines below in locating  
the vent terminal to help insure trouble-free operation of a sidewall vented furnace:  
•
Avoid locating the vent terminal on a wall facing prevailing winds and wide-open areas. When  
impractical, choose a location that protects the vent from strong winds, such as behind a fence or  
hedge.  
•
•
In geographical areas with considerable snowfall, it is advisable to locate the vent terminal much higher  
than the minimum 12-inches above ground to prevent blockage by snow accumulation or drifting.  
The vent and combustion air terminations shall be checked periodically, at least at the start of each  
heating season, for restriction or blockage from foreign material in the exhaust vent or in the air intake  
piping. Clean the air intake and vent terminations when necessary.  
E1. Single-Pipe (Sidewall) Venting Option  
NOTICE: When possible, we recommend all furnace of the model series CHB1 / CDB1 be installed to  
utilize outside combustion air. The use of outside combustion air usually results in the most energy  
efficient, nuisance free, and long-lived operation of the furnace.  
NOTICE: Heat exchanger failure accelerated by contaminated combustion air will void the furnace heat  
exchanger limited lifetime warranty.  
This furnace may be horizontally, i.e. sidewall, vented using an exhaust vent pipe alone without drawing in  
outside combustion air. When single-pipe, sidewall venting a furnace, combustion air is drawn from the indoor  
space. This type of installation is not classified as a direct vent installation. However, the same exhaust venting  
guidelines apply as for a direct vent installation, except the exhaust termination will be similar to the air intake  
of the "two- pipe", direct vent installation. Refer to depictions of proper intake terminal installations in Figures 2  
and 3. Referring to the left-hand (LH) sketch in Figure 2, vent termination will consist of one (1), 90° elbow,  
opening downward.  
When indoor air is used for combustion, measures should be taken to prevent drawing in corrosive chemicals  
vapors or gases with the combustion air supply. Such chemicals include, but are not limited to, chlorinated  
and/or fluorinated hydrocarbons such as found in refrigerants, aerosol propellants, dry cleaning fluids,  
degreasers and removers. Other harmful compounds may come from bleaches, air fresheners or mastics. Vapors  
from such products can form reactive acid producing chemical species when burned in a gas flame. The life of  
the furnace could be reduced should acidic compounds form within the furnace.  
F. Installation Of Outside Exhaust / Intake Terminations  
1. After determining appropriate installation locations (suitable locations must observe all clearances specified  
in this manual), mark and cut two (2) holes in the outside wall of the following sizes for the outdoor  
terminal(s),  
•
•
2-3/8 inch diameter, for furnace models CHB1 / CDB1-50 and CHB1 / CDB1-75, or  
3-1/2 inch diameter, for the furnace models CHB1 / CDB1-100 and CHB1 / CDB1-125.  
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2. Measure and cut two (2), 2-inch diameter thermoplastic pipes 1-1/2 inches longer than the depth of the wall.  
(Cutting the pipe longer leaves a ¾ inch connection allowance at both ends of the pipe.) For 3-inch diameter  
PVC pipe, leave a 3-inch allowance for end connections. Using PVC pipe cement, glue a PVC elbow or  
coupling fitting to one (1) end of each pipe.  
Before inserting the pipe through the wall, mark the other end of the pipe so the elbow orientation can be  
determined. Also, if a protective shield (refer to Section E., passage 1. of this manual) will be used on the  
exterior surface of the wall, it should be installed at this time. From the inside, glue a coupling fitting to  
each pipe, using PVC pipe cement, while being careful to maintain the proper orientation of the termination  
elbow(s). Complete the assembly of the outlet and inlet as shown in Figure 5, making sure that the spacing  
between the inlet and outlet complies with that noted in Figure 3.  
Figure 5: Typical Construction Details of Sidewall Vent and Air Intake Terminations  
3. Finish the vent installation by caulking the annulus to seal around the two (2) holes where the thermoplastic  
pipes pass through the wall.  
4. To prevent foreign material, insects, or small animals from entering the pipes, an optional vent or intake  
terminal (stainless steel) screen is available from Thermo Products under part no. 320226 for 3” vent and  
320219 for 2” vent.  
5. Optional Direct Vent Terminations  
Three optional vent kits are available for direct vent terminations, refer to Figure 6.  
•
•
The concentric vent kits (Thermo Products p/n AOPS7488 & AOPS7489) provide a means for the vent  
and intake to be installed through a single opening in the roof or exterior wall. Kit p/n AOPS7488  
requires a 4” inch diameter hole and is used on furnace models CHB1/CDB1-50 & 75. Kit p/n  
AOPS7489 requires a 5” inch diameter hole and is used on furnace models CHB1/CDB1-100 &125.  
The sidewall vent cap (Thermo Products part no. 370191) is a cover installed over the exhaust vent and  
air intake pipes on the exterior of the building. For horizontal sidewall vent applications only. This kit  
may be used on any size furnace in the CHB1/CDB1 family.  
Install these optional kits according to the instructions provided with each kit. The location and clearance  
requirements are identical to those of the standard vent terminations described in this manual.  
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370191  
AOPS7488 / AOPS7489  
SIDE WALL VENT KIT  
CONENTRIC VENT KIT  
VERTICAL  
HORIZONTAL  
Figure 6: Optional Direct Vent Kits for the CHB1 / CDB1 Model Series of Furnaces  
G. Connecting The Furnace To Roof Exhaust / Intake Terminations  
If it is not desirable, or feasible, to vent the furnace through a sidewall, it may be vertically vented through the  
roof. Installation shall conform to the following guidelines, which are illustrated in Figure 6A, below.  
1. The outlet of the exhaust vent and the inlet of the combustion air intake, i.e. the terminations, shall be a  
minimum of 12-inches above highest anticipated snow level.  
2. The exhaust vent outlet must be installed a minimum of 12-inches above the air intake inlet.  
3. Where exposed to prevailing winds, the combustion air intake shall be installed upwind of the vent outlet.  
4. The exhaust vent and combustion air intake shall be a minimum of 3-inches and a maximum of 24 inches  
apart.  
NOTICE: When the vent termination is installed correctly, a draft should NOT be present in the system  
during the furnace off-cycle.  
Figure 6A: Typical Rooftop Vent and Air Intake Termination Construction Details  
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H. Exhaust / Intake Piping And Condensate Drain Connections At Furnace  
1. Figures 6B, 7, and 8 follow depicting typical exhaust vent and air intake connections for the furnace model  
series CHB1 and the CDB1, respectively, as well as a list of required parts to correctly install each system.  
Figure 6B: Required Exhaust Vent and Air Intake Piping for CHB1 Furnace  
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Figure 7: Required Exhaust Vent and Air Intake Piping for CDB1 Furnace in Downflow Applications  
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Figure 8: Required Exhaust Vent and Air Intake Piping for CDB1 Furnace in Horizontal Applications.  
2. Connecting The Exhaust Vent To The Inducer  
a. Slip the end of the 2-inch diameter PVC elbow (for the model CDX1 in horizontal applications, the 2-  
inch diameter PVC tee assembly) over the outlet of the inducer blower assembly. Measure the length of  
2-inch diameter thermoplastic pipe needed to clear the furnace side casing, while allowing for  
installation of a 2-3/8 inch length of reinforced rubber hose, used as a coupling, within the casing of the  
furnace. Cut the measured lengths of 2-inch diameter PVC pipe being sure to allow a sufficient length  
of pipe for connections. Refer to Figures 9, 10 and 11 for assembly details.  
NOTICE: For the models CDB1-50 / -75, a length of 2-inch diameter PVC pipe and a 2-inch  
diameter PVC tee assembly are supplied with each furnace. For the models CDB1-100 / -125, a 3-inch  
x 2-inch diameter PVC reducer is also supplied.  
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NOTICE: For models CDB1-100 and CDB1-125 used in horizontal applications, immediately  
transition from 2-inch to 3-inch diameter pipe by installing the 3-inch x 2-inch diameter PVC reducer  
just outside the furnace casing. The remainder of the venting system leading away from the furnace  
must be composed of 3-inch diameter PVC pipe and pipefittings only. Refer to item E in Figure 8.  
b. After preparation of the internal 2-inch diameter PVC pipe sections, put a thin bead of a silicone rubber  
type sealant around the outlet flange of the inducer. Slip the 2-inch diameter PVC elbow (for the model  
series CDB1 in horizontal applications, a 2-inch diameter PVC tee) over the inducer outlet flange.  
Drive one (1) #8 x 3/4 inch sheet metal screw with black protective coating (supplied with furnace)  
through the elbow and into the outlet flange of the inducer to secure the elbow in place.  
Figure 9: Typical Internal  
Vent Piping Arrangement for  
the Furnace Model Series  
CHB1.  
Figure 10: Typical Internal  
Vent Piping Arrangement for  
the Furnace Model Series  
CDB1-100 / -125.  
Figure 11: Typical Internal  
Vent Piping Arrangement for  
the Furnace Model Series  
CDB1-100 / -125 in RH  
Horizontal Applications.  
c. Using PVC cement, glue the pre-cut 2-inch diameter thermoplastic pipe, from step (a) above, to the 2-  
inch diameter PVC elbow (for the model series CDB1 in horizontal applications, the 2-inch diameter  
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PVC tee). Couple the drain tee assembly to the pre-cut 2-inch diameter PVC pipe using the reinforced  
rubber hose and the two (2) band clamps supplied.  
NOTICE: All PVC thermoplastic pipe must be supported beginning directly over the exhaust  
vent tee assembly, then every 4-feet thereafter, and at every joint. Trial fit the entire exhaust vent  
and air intake piping systems, making sure the slope and length of the piping are correct, before  
permanently assembling the pipe components.  
If the vent piping is run through an unconditioned space, it must be insulated with 1-inch thick  
foil-faced fiberglass insulation, or an equivalent product.  
3. Connecting The Combustion Air Intake Piping  
: Outside combustion air must NOT be drawn from an area directly adjacent to a pool, hot  
tub or spa. Measures should be taken to prevent the entry of corrosive chemicals or vapors into the  
combustion air supply. Such chemicals include, but are not limited to, chlorinated and/or fluorinated  
hydrocarbons such as found in refrigerants, aerosol propellants, dry cleaning fluids, degreasers and  
removers. Other harmful compounds may come from bleaches, air fresheners or mastics. Vapors from  
such products can form reactive acid producing chemical species when burned in a gas flame. Should  
acidic compounds form in the furnace they may significantly reduce the useful life of the furnace.  
a. For the models CHB1–50 / –75 and CDB1–50 / –75, install a 2-inch PVC elbow with sleeve and  
coupling (for models CHB1–100 / –125 and CDB1–100 & –125, a 3-inch PVC elbow with sleeve) on  
the inlet of the burner box. Measure the length of pipe needed to clear the casing. Be sure to allow  
sufficient length to account for insertion of the pipe into the elbow at the burner box and the elbow, or  
coupling fitting, on the end. Cut the pipe to length.  
b. After preparation of the thermoplastic pipe, drive one (1) #8 x 3/4 inch sheet metal screw with black  
protective coating (supplied with furnace) through the PVC coupling, or sleeve, into the metal collar of  
the burner box to secure the piping in place.  
NOTICE: DO NOT apply silicone rubber type sealant or PVC cement to the joint at the  
thermoplastic piping connection to the metal burner box collar. Attach the PVC elbow to the  
sleeve and then to the coupling where required, using silicone rubber type sealant, refer to  
Figure 12.  
c. Insert the precut 2-inch (or 3-inch) thermoplastic pipe into the elbow at the burner box and to the  
elbow, or coupler, just outside the furnace using a silicone rubber type sealant. To properly make these  
seals, run a thin bead of silicone type sealant around the circumference of the PVC pipe, about 3/8 inch  
from either end. Insert the straight pipe section into the appropriate couplings and elbows and rotate 1/4  
turn. Silicone rubber type sealants remain pliable after the initial setup period has passed allowing for  
relatively easy disconnection of the air intake system, should the burner assembly require removal at a  
later date, refer to Figure 12.  
NOTICE: When applying silicone sealants, ensure that no excess sealant is pushed into the inside  
opening of the pipe. This may cause flow restriction within the piping. If possible, always apply  
the sealant to the male component of the piping joint.  
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DO NOT! SILICONE OR SEAL  
THIS CONNECTION IN  
ANYWAY. MUST BE LOOSE  
FIT WITH LEAKAGE BETWEEN  
PVC AND METAL COLLAR.  
Figure 12: Typical Internal Air Intake Piping Arrangement for All Furnace Models  
d. After trial fitting the entire combustion air intake system, use a PVC cement to glue all connections in  
place, except the length of pipe between the combustion air fitting on the burner box and the first  
fitting.  
e. If the combustion air piping is installed in a warm, humid place, such as a laundry room or above a  
suspended ceiling, it must be insulated with a 1-inch thick, foil-faced fiberglass insulation, or an  
equivalent product, to help prevent the outside surface of the pipe from sweating.  
I. Condensate Drain Line And Trap Assembly  
1. The following diagrams depict typical condensate drain and trap connections for the furnace models series  
CHB1 and CDB1, refer to the illustrations in Figures 14, 15, and 16.  
Figure 14. Condensate Trap Assembly Mounted On the Model Series CHB1  
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Figure 15. Condensate Trap Assembly Mounted On the Model Series CDB1 In a Downflow Application  
Figure 16. Condensate Trap Assembly Mounted On The Model Series CDB1 In RH Side Horizontal  
Application  
2. Determine from which side of the furnace the condensate disposal line will be run.  
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NOTICE: On the model series CHB1 / CDB1 the condensate disposal line must be on the same side  
as the flue outlet or, in the case of a horizontal application, the bottom of unit.  
Drive two (2) #8 x 3/4 inch sheet metal screws with black protective coating (supplied with furnace) to  
attach the condensate trap to the furnace casing. Pilot holes are provided on both sides of the casing for  
mounting the trap.  
NOTICE: When the CDB1 series unit is used in a horizontal application, the connection of the  
drain hose to the collector box must be changed from the standard, factory-supplied location to a lower  
location on the collector box to permit proper drainage of condensate from the furnace. A knockout has  
been provided in the furnace side casing for the drain hose to exit. The connection change can be  
accomplished as follows. Refer to Figure 16 for a depiction of a properly completed relocation.  
a) Locate and disconnect the drain hose from the standard connection location at the collector box.  
b) Locate and uncap the drain at the bottom (with the furnace lying on a side) of the collector box.  
c) Connect the drain hose from Step (a) to the uncapped bottom drain from Step (b).  
d) Close off the previous drain connection from Step (a) with the cap removed in Step (b).  
3. Attach one (1) drain hose (a length of 11/16 inch O.D. clear, colorless tubing) to the front  
connection (on the model series CHB1) or the bottom connection (on the model series CDB1) of the  
condensing coil cover plate.  
Insert the snap-in-place plastic bushing, provided in the furnace parts package, into the proper hole in  
the furnace casing to prevent cuts in the drain tubing. Route the drain tubing through the bushing.  
When making connections with the clear tubing, carefully route the tubing in a manner to prevent  
kinking or abrasion of the tubing.  
Slip the free end of the drain hose over the hose barb on one (1) side of the plastic hose barb tee  
provided in the CPVC (chlorinated polyvinyl chloride) thermoplastic condensate trap assembly.  
Secure the drain hose with the spring-type hose clamp provided in the parts package.  
4. Trial fit the second drain hose (a length of 11/16 inch O.D. clear, colorless tubing provided in the  
furnace parts package) from the hose barb on the bottom of the PVC exhaust vent drain tee to the  
plastic hose barb tee provided in the condensate trap assembly. Make sure the hose is long enough not  
to kink or be otherwise restricted once installed. Mark the minimum length of drain hose required for  
the application. Remove any extra length from the drain hose. Attach the drain hose to the hose barb  
on the other side of the condensate trap tee. Slip the other end of the drain hose on to the hose barb of  
the PVC drain tee assembly; refer to Figure 15 for an illustration. Use the spring-type hose clamp(s)  
provided in the parts package to secure all connections.  
5. Plan, source, and install a condensate drain line using ½ inch diameter CPVC (chlorinated polyvinyl  
chloride) thermoplastic pipe and pipefittings. Route the line in the shortest possible manner to reach a  
nearby drain. Secure all joints using CPVC cement. For gravity drainage, the condensate drain line  
must maintain a minimum ¼ inch per foot downward slope toward the drain. The drain line must be  
watertight, supported, and secured such that it cannot be easily moved.  
NOTICE: If an air conditioning condensate drain line is combined with the furnace condensate drain  
line, the air conditioning evaporator coil must have a separate trap installed ahead of the connection  
joint.  
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6. A condensate pump may be required when,  
•
•
•
a suitable drain is not present,  
the drain is above the trap outlet level on the furnace, or  
the drain line cannot be sloped downward its full length to the drain.  
If gravity drainage of the condensate from the furnace to a drain is impractical for any of these reasons,  
a condensate pump (part # 350225) is available from Thermo Products. Follow the pump  
manufacturer’s instructions for proper installation.  
7. CAUTION: Continual exposure to condensate may injure plants and damage certain building  
materials, including many metals, wood, stone, and concrete.  
Flue gas condensate is slightly acidic with a pH of about 3.5. (A pH level of 7.0 is considered neutral.  
Carbonated cola drinks with a pH of 3.1 are actually slightly more acidic than condensate.) If local  
codes require an acid neutralizing kit, a kit is available from Thermo Products under part no. 320095.  
Follow the instructions enclosed with the neutralizing kit for proper installation.  
8. The condensate piping in the furnace and the drain system should be flushed out at the start of every  
heating season. This will ensure trouble free operation and will keep the acidity level well above a pH  
of 3.4, i.e. more towards neutral.  
To flush the condensate drain system, follow these steps.  
a. Turn off electrical power to the furnace at the disconnecting switch and adjust the room thermostat  
to “OFF”, or to the lowest temperature setting.  
b. Flush the drain system by removing the drain hose from the secondary heat exchanger coil drain  
nipple and running tap water into the open end of the tubing. Run at least a quart of water through  
the drain system or more, until the water leaving the drain system is clear and colorless in color  
and free of any particulate matter.  
c. Replace the drain tubing by pushing it firmly onto the nipple. Make sure the spring-type hose  
clamp is returned to the original position to prevent leaks.  
d. If any of the electrical controls are inadvertently wetted during the flushing process, dry them with  
a soft cloth and wait 24 hours before operating the furnace.  
e. Adjust the room thermostat to the “HEAT” position, or to the desired temperature, and restore  
electrical power to the furnace.  
J. GENERAL GAS PIPING  
: Because of the potential of odorant fade, a gas leak may not be detected by smell. If this  
furnace is installed below grade, contact your gas supplier for a gas detector.  
1. Left and right gas supply piping - These furnaces are set-up to be gas piped through either the left or right  
side by using a street elbow and a straight pipe. For the purposes of service, it is recommended that the gas  
union be located inside the furnace, when possible.  
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Figure 18  
2. A drip leg must be used on both LP and natural gas installations prior to the furnace in order to trap oil,  
condensate and other impurities which might otherwise lodge in the gas valve or plug the burner orifice. A drip  
leg shall be provided at the outlet of the gas meter when there is excessive condensation between the gas meter  
and the furnace. Failure to install a drip leg may void the limited warranty on the furnace.  
: All gas piping must be leak tested using a soap and water solution (when the gas is turned on)  
following the procedure outlined in Section III, J, of this manual. A final test for gas leakage must be made after  
purging the gas line (refer to Section IV, B, of this manual). This test must be conducted with the unit operating  
and should include the furnace piping and gas valve. Never use an open flame to check for a gas leak.  
: Care must be taken not to wet electronic components during leak test. Wetting the primary  
ignition module may damage its circuitry and cause a hazardous situation. Dry moisture from all leads and  
terminals if wetting occurs. Wait at least 24 hours for the circuit to fully dry before energizing the burner circuit.  
J1. REQUIREMENTS AND SIZING OF DUCT WORK  
The duct system must be sized and installed by a qualified installer or service person, following the design standards  
of the Air Conditioning Contractors of America (ACCA) or ASHRAE.  
1. When it is located in the same room as the furnace, a return air register must be installed a minimum of 20 feet  
away from the furnace.  
2. The return air duct shall also be sealed to the furnace and also terminate outside of the furnace space, if supply  
ducts carry circulated air to areas outside the space containing the furnace.  
3. The return air duct system must equal the supply air duct system in its capabilities. Use a supplier's catalog for  
proper sizing of outlet and return air registers and grills to ensure that they meet the CFM requirements of the run to  
which they are connected.  
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4. If the furnace is used in connection with an air conditioning evaporator coil, the furnace must be installed parallel  
with or on the upstream side of the coil, to prevent condensation in the heat exchanger. If the evaporator coil is  
installed with a parallel flow arrangement, dampers or other means to control flow of air should be installed to  
prevent chilled air from entering the furnace. If such a device is manually operated, it must be equipped with a means  
to prevent operation of either the furnace or air conditioner unless it is in the full heat or cool position.  
We recommend that the outlet duct be equipped with a removable access panel to allow for visual inspection of the  
heat exchanger to check for leakage or to allow for insertion of a probe sampler in the air stream. This removable  
access cover should be attached to ensure there is no air leakage.  
5. The duct system shall be sized for the maximum CFM requirement of the installation whether it is for heating or  
cooling. Two common rules for heating and cooling follow:  
A. 400 CFM (1200 BTU's) per ton of cooling is required.  
B. 14 CFM of heating per 1000 BTU's of furnace output based on its steady state efficiency and a 55° to 85°  
temperature rise.  
EXAMPLE: Heating output of a furnace is 100,000 BTU/HR  
100,000 BTU x 14 cfm  
1000 BTU  
=
1400 CFM  
Air conditioning installed is 4 tons x 400 CFM = 1600 CFM or 48,000 BTU’s. NOTE: The duct system must be  
sized for the larger CFM requirement for cooling. If only 3 tons 36,000 BTUs of cooling x 400 CFM = 1200 CFM  
was installed, the duct would have to be sized for the 1400 Cfm heating requirement.  
Figure 18A  
All trunk lines, take-offs, registers and grill-free areas must be figured when determining the air handling capacity of  
a duct system. One can obtain the necessary duct system size by utilizing the chart below. (For example, see Figure  
18A.) Use a supplier’s catalog for proper sizing of outlet and return air registers to insure that the register will meet  
the CFM requirements of the run to which it is connected.  
The main trunk lines, take offs, registers and grills of the supply return air duct system must have an adequate square  
inch area to move the desired CFM in order to achieve proper movement. The following chart shows the CFM air  
handling capability based on a 0.1” SP loss in the supply duct system. The total external static pressure should not  
exceed .2 inches water column.  
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DUCT SIZES FOR HOMES, QUIET OFFICES, OR SIMILAR INSTALLATIONS  
TABLE 2A  
Each of the system components (trunk lines, take offs, runs and register and grill-free areas) must be properly sized  
and matched together to ensure the necessary air handling capacity of a duct system. A 12" x 8" duct with a 400  
CFM capacity for example will not flow 400 CFM if the register(s) to which it connects only flow a total of 200  
CFM.  
The speed of the blower motor may have to be changed to obtain the proper 55°F to 85°F (35°F to 65°F CHB1-75)  
temperature rise for heating when an air conditioning coil is installed. This depends on the static resistance of an  
individual duct system and the size of the air conditioner.  
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K. FILTERS  
1. CHB1 MODELS: HIGHBOYS  
It is necessary to cut the return air opening in the bottom or side casing depending upon the needs of the specific  
installation.  
NOTICE: If your CHB1 will require air delivery above 1800 CFM, it is advisable that both sides, a combination of  
1 side and the bottom, or the bottom only be used for return air. (If a return is cut in the bottom, it should be as large  
as the return opening in the equivalent CDB1 model. (See specification sheet in beginning of this manual).  
This CHB1 furnace has been factory supplied with a high quality re-usable filter rated for air velocities up to 600  
ft/min. An optional Thermo Products filter rack assembly (part no. AOPS7547 for CHB1-50 thru 100 and  
AOPS7375 for CHB1-125) is available which is sized for the filter provided.  
If an optional Thermo Pride filter rack AOPS7547 (figure 19) is used with the furnace, it will serve as a template to  
scribe a mark for the return air opening on the casing. Place the filter rack on the casing one inch up from the bottom  
of the furnace and centered from side to side. Place the securing flange against the casing for locating the return air  
opening.  
Figure 19  
PLEASE NOTE: While scribing the return air opening, the filter rack can be held into position by tape or similar  
means.  
Position the open end of the filter rack so that it is accessible for filter replacement. Once the filter rack is positioned  
correctly, scribe a line along the inside of the securing flange of the filter rack on three of the sides. To scribe a line  
on the fourth side, on the open end, use the open end support for a guide.  
Remove the filter rack and cut the return air opening in the casing. Now the filter rack can be permanently attached  
to the furnace with screws or pop-rivets along the securing flange.  
Connect the return plenum to the filter rack and slide the filter into place.  
2. CDB1 MODELS: COUNTERFLOWS  
This CDB1 furnace has been factory supplied with two high quality reusable filters rated at 600 ft/min. These filters  
are designed to be mounted on the return air plenum opening on the top of the furnace in the double “vee” style rack  
provided (see Figure 20). If feasible, it is recommended that slits be cut in the return front to allow for easier access  
of the filters.  
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Figure 20  
3. USE OF NON-THERMO PRIDE FILTER RETENTION MEANS  
If a method other than the Thermo Pride filter rack is selected for retention of the filter and/or use of a different filter  
type is desired, see Table 3 for minimum size guidelines for selecting a filter system for the CHB1 or CDB1  
furnaces.  
MINIMUM FILTER AREA REQUIRED (LENGTH X WIDTH, SQ. IN.)  
TABLE 3  
FILTER TYPE  
MAXIMUM  
RATE  
REQUIRED CFM/(FILTER VELOCITY RATING X 144)=  
FILTER (IN2)  
AIR  
VELOCITY  
FURNACE MODEL  
CHB1,CDB1-50 CHB1,CDB1-75 CHB1,CDB1-100 CHB1,CDB1-125  
*THERMO PRODUCTS 600 FT./MIN.  
SUPPLIED  
172 IN.2 *  
254 IN.2*  
328 IN.2*  
402 IN.2*  
PERMANENT FILTER  
STANDARD  
PERMANENT FILTER  
DISPOSABLE TYPE  
FILTER  
500 FT./MIN.  
300 FT./MIN.  
208 IN.2  
344 IN.2  
304 IN.2  
506 IN.2  
394 IN.2  
656 IN.2  
484 IN.2  
804 IN.2  
* The Thermo Products supplied filter can be cut to size to fit other filter retention systems as long as the minimum  
size requirement is met. NOTICE: Any internal stiffeners used in the filter must not be removed, although they can  
be cut to size as needed.  
NOTICE: The filter areas in table 3 are the minimum areas required based on the CFM generated by the furnace  
for standard heating speeds only. The following formula can be used to determine the minimum filter area required  
for cooling if the unit is equipped with cooling. This value should then be compared to the value shown in table 3  
and the larger of the two should then be used for determining the minimum filter area required for that installation.  
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FORMULA:  
(tons of cooling) x (400 CFM per ton) (144 square inches per foot)  
(max. air velocity of filter from table 3 for the filter type)  
= filter area sq.inches  
= length x width of  
filter in inches  
EXAMPLE: If you had a CHB1-100 furnace and 4 tons of cooling and a standard permanent filter.  
4 tons x 400 CFM x 144 = 460 square inches for cooling  
500  
For heating a CHB1-100 needs 394 square inches of filter. The filter system must be designed for the larger CFM  
requirement determined for cooling of 460 square inches. A filter would have to be sized so that the area (length X  
width) was at least 460 sq. in.  
L. WIRING  
All wiring shall be performed by a qualified electrician or service person. The wiring must comply with local codes,  
the instructions in this manual, and in the absence of codes with the National Electrical Code (ANSI/NFPA-70 or  
latest edition).  
1. The following items are guidelines to complete the wiring portion of the installations.  
a. A separate power supply circuit with over current protection and a disconnect switch must be provided. See  
furnace specifications or furnace rating label for maximum fuse size.  
b. All CHB1 and CDB1 Series furnaces are supplied with a fuse disconnect switch box to be mounted on the  
outside surface of the right or left side casing so a fuse disconnect can be mounted on the furnace. Make the 115  
volt supply connection in this junction box. A green screw and a strain relief are provided in order to connect the  
power supply ground wire and provide strain relief for the 115 volt power leads from the furnace in the fuse  
disconnect box. A disconnect switch can be field mounted on the 2x4 box provided. If not, the disconnect switch  
must be located reasonably close to and within sight of the furnace.  
NOTICE: The hot surface igniter and operation of this furnace depends on correct polarity. The hot leg of the  
supply circuit must be connected to the black line lead and the common leg to the white line lead in the field  
mounted junction box. The hot leg must pass through the disconnect switch in all cases to prevent the hazard of  
electrical shock when servicing.  
IMPORTANT: The furnace must be grounded in accordance with local codes and with the National Electrical  
Code (ANSI/NFPA NO. 70 or latest edition) when an external electrical source is utilized.  
2. ELECTRONIC AIR CLEANER (EAC) AND HUMIDIFIER INSTALLATION  
The ignition module on this furnace has designated terminals to control the operation of an electronic air cleaner  
and/or humidifier. These terminals provide line voltage (110-20VAC) for the control of these accessories. (See  
Figure 21). NOTICE: It is important to confirm that the operating voltage of the humidifier or EAC being installed  
matches the output of this control. If not, a field supplied relay or transformer may be necessary to provide the  
proper control and supply voltage for the accessory being installed. See the manufacturers instructions for the  
humidifier or EAC for additional instructions.  
3. THERMOSTAT ANTICIPATOR SETTING  
Proper control of the indoor temperature can only be achieved if the thermostat is calibrated to the heating and/or  
cooling cycle. A vital consideration of this calibration is related to the thermostat heat anticipator.  
The proper thermostat heat anticipator setting is 0.8 AMPS for furnace operation only. To increase length of cycle,  
increase setting of heat scale; to decrease length of cycle, decrease setting of heat scale.  
Anticipators for the cooling operation are generally pre-set by the thermostat manufacturer and require no  
adjustment.  
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Anticipators for the heating operation are of two types, pre-set and adjustable. Those that are pre-set will not have an  
adjustment scale and are generally marked accordingly.  
4. BLOWER MOTOR SPEED WIRING  
Figure 21  
: TURN OFF THE ELECTRICAL POWER to the furnace before attempting to change blower  
speed wiring.  
A. The furnace is factory wired to the ignition control with standard heating and cooling speeds.  
When changing motor speeds, simply switch the needed speed to either the heating or cooling terminal  
as applicable on the module to obtain the desired CFM. The unused speeds should then be reconnected  
to the module in the “park” positions.  
B. The optional blower delay switches on the W/R integrated control (figure 21) are used to determine the  
length of the heat delay-to-fan-on and delay –to-fan-off periods. The following tables show the time  
periods that will result from the various switch positions.  
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BLOWER DELAY SETTINGS  
To delay fan  
turn-on by:  
15 sec.  
30 sec.  
*45 sec.  
Set Switch  
#1  
Off  
Off  
On  
On  
#2  
Off  
On  
Off  
On  
60 sec,  
To delay fan  
turn-off by:  
60 sec.  
90 sec.  
*120 sec.  
180 sec.  
Set Switch  
#3  
On  
Off  
On  
Off  
#4  
On  
On  
Off  
Off  
*Factory Settings For Optimal Performance  
5. FIELD WIRING AND REPLACING WIRING  
Field wiring between the furnace and devices not attached to the furnace shall conform with the temperature  
limitation for Type T wire [63°F rise (35°C)] when installed with the manufacturers instructions. If any of the  
original factory supplied furnace wiring is replaced or a separate device other than the thermostat is wired internal to  
the unit 105°C thermoplastic or equivalent wire must be used.  
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IV. STARTING THE UNIT  
A. SEQUENCE OF OPERATIONS  
AT ANY TIME THE  
GAS VALVE IS  
CONTINUOUS SAFE OPERATION CHECK  
IF FLAME SIMULATION CONDITION  
NOT ENERGIZED  
PRESENT OR ROLL-OUT SWITCH OPENS, SYSTEM  
ENERGIZES INDUCER FAN FOR 15 SECONDS AND CIRCULATOR BLOWER AT  
HEATING SPEED UNTIL SITUATION CORRECTION  
START  
THERMOSTAT CALLS FOR  
HEAT, CONTACTS CLOSE  
CONTROL BOARD ENERGIZED,  
INDUCER ENERGIZED  
PRESSURE SWITCH SENSES  
PRESSURE SWITCH SENSES  
NEGATIVE PRESSURE(NO DRAIN BLOCKAGE)  
ADEQUATE DIFFERENTIAL PRESSURE,  
CONTACTS CLOSE  
CONTACTS CLOSE  
(CDB1 SERIES ONLY)  
POWER IS APPLIED TO  
THE SILICON NITRIDE  
IGNITOR. IGNITOR  
POWER INTERRUPTION  
SYSTEM SHUTS OFF,  
RESTARTS WHEN POWER  
IS RESTORED.  
WARM-UP IS 20 SECONDS.  
START  
TRIAL  
FOR  
AFTER IGNITOR WARM-UP,  
THE GAS VALVE IS  
ENERGIZED TO OPEN  
IGNITION  
FLAME MUST BE DETECTED  
WITHIN 4 SECONDS IF  
FLAME IS DETECTED, THE  
DELAY-TO-FAN-ON TIME  
BEGINS (45 SECONDS)  
IF FLAME IS NOT DETECTED, THE  
GAS VALVE IS DE-ENERGIZED,  
THE IGNITOR IS TURNED OFF AND  
THE CONTROL BOARD CONTROL GOES  
INTO "RETRY" SEQUENCE.  
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AFTER DELAY-TO-FAN-ON  
PERIOD ENDS, CIRCULATING  
AIR FAN IS ENERGIZED AT  
HEATING SPEED. THE (OPTIONAL)  
ELECTRONIC AIR CLEANER  
AND HUMIDIFIER ARE  
THE RETRY SEQUENCE  
PROVIDES A 60 SECOND  
WAIT BEFORE IGNITION  
RETRY. RETRY IS  
ATTEMPTED WITH AN  
ADDITIONAL 10 SECONDS  
OF IGNITOR WARM-UP  
TIME.  
MAIN  
BURNER  
OPERATION  
ENERGIZED.  
WHEN THERMOSTAT IS  
SATISFIED, CONTACTS  
OPEN AND THE GAS  
IF IGNITION ATTEMPT IS  
UNSUCCESSFUL, ONE MORE  
RETRY WILL BE MADE  
BEFORE THE CONTROL BOARD  
GOES INTO SYSTEM LOCKOUT.  
CALL  
FOR  
HEAT  
VALVE IS DE-ENERGIZED.  
AFTER PROOF OF FLAME  
LOSS, INDUCER STARTS 5 SECOND  
POST SURGE AND (OPTIONAL)  
HUMIDIFIER ARE  
SATISFIED  
DE-ENERGIZED. THE DELAY-  
TO-FAN-OFF PERIOD  
BEGINS (120 SECONDS)  
IF FLAME IS DETECTED,  
THEN LOST, THE CONTROL BOARD  
WILL REPEAT THE INITIAL IGNITION  
SEQUENCE FOR A TOTAL OF SIX  
RECYCLES. AFTER SIX UNSUCCESSFUL  
RECYCLE ATTEMPTS, THE CONTROL  
WILL GO INTO SYSTEM LOCKOUT.  
AFTER THE DELAY-TO-  
FAN-OFF PERIOD ENDS,  
THE CIRCULATING AIR  
FAN AND (OPTIONAL)  
ELECTRONIC AIR CLEANER  
ARE DE-ENERGIZED.  
END  
OF CYCLE  
IF SYSTEM IS IN LOCKOUT, THE  
MODULE WILL RESET ITSELF AFTER  
60 MINUNTES OR MAY BE MANUALLY RESET BY  
INTERRUPTING THE POWER TO THE  
FURNACE AT THE DISCONNECT OR INTERRUPTING  
THE CALL FOR HEAT AT THE THERMOSTAT.  
IF THIS DOES NOT RESTART THE SYSTEM,  
REFER TO THE TROUBLESHOOTING  
SECTION OF THIS MANUAL.  
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B. INITIAL START UP:  
This furnace does not have a pilot. It is equipped with a hot surface igniter, which automatically lights the burner. Do  
not attempt to light the burner by hand. Check the following items before the initial start-up.  
1. Check all wiring for loose connections and proper hook up.  
2. Leak test gas piping connections.  
3. Check all tubing to the pressure switch and drains to make sure they are connected firmly at all their connection  
points.  
4. Check flue pipe, combustion air inlet and all PVC connections for tightness and to make sure there is no  
blockage.  
5. Make sure air filter is in place.  
6. Make sure the outside vent and air intakes are installed according to instructions and that they are free from  
blockage.  
7. Make sure that the drain trap is properly connected to the furnace and to the buildings drain system.  
OPERATING INSTRUCTIONS:  
: Turn off power to furnace before it is placed into service. The gas piping system must have been  
leak tested by a qualified heating contractor. (See Section III, J, of these instructions on the installation of gas  
piping).  
: It may be necessary to purge the air out of the gas line for initial start-up of the furnace after  
installation. This should be done by a qualified heating contractor. If excessive gas escapes when purging the  
gas supply at the union, allow the area to ventilate for at least 15 minutes before attempting to start the furnace.  
LP gas is especially dangerous because the specific gravity of LP gas allows it to accumulate at floor level at a  
dangerous concentration. For remainder of operating instructions, reference Users Information Manual.  
: Heat exchanger oil will burn off on initial firing creating an unpleasant odor. To prevent this  
odor from occurring more than once, it is suggested that:  
1. A window(s) be opened.  
2. The thermostat be set at highest setting.  
3. The furnace remain running at conditions 1&2 for 30 minutes or until odor has dissipated.  
C. ADJUSTMENT OF BTU INPUT RATE  
The Orifice for this furnace was sized: 1) for natural gas having a heating value of 1025 BTU per cubic foot and a  
specific gravity of .65, or 2) for liquefied propane gas with a heating value of 2500 BTU per cubic foot and a  
specific gravity of 1.55. The information plate inside the furnace vestibule will specify which gas your furnace is  
orificed for. If the furnace is installed at an altitude that is more than 2,000 feet above sea level, it is mandatory that  
the input to the burner be reduced 4.0% for every 1,000 feet that it is above sea level. If the furnace is installed at an  
elevation of 5,000 feet, its input must be reduced 20.0%. Example: a furnace rated at 100,000 BTU at sea level must  
be reduced to a firing rate of 80,000 (100,000 X .80 = 80,000) at an elevation of 5,000 feet. If the furnace is  
installed at an elevation of 2,000 feet or less, no reduction in input is required. Your gas supplier will supply you  
with the correct orifice sizing information.  
To check the input of your natural gas furnace, allow the unit to operate for 10 to 15 minutes and proceed as follows:  
a. Call your gas supplier and ask for the BTU content (heating value) of one cubic foot of the gas, supplied to  
the installation area. An alternate approach is to assume a value of 1025 BTU/Cu Ft, which is the national  
average.  
b. With all other gas appliances turned off and using a stopwatch, clock the time required for the (small) dial  
on the gas meter to make one full revolution. The meter will state how many cubic feet is flowed for one  
revolution usually one, two or five. The unit must have been in operation at least 10 minutes  
before clocking.  
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FORMULA: BTU/CU FT X NUMBER OF CU FT X 3600 SECONDS = INPUT BTU/HR  
EAMPLE: 1025 BTU/CU FT X 2 CU FT X 3600 = 98,633 BTU INPUT 74.8 SECONDS  
Check for the model number of this furnace, its input, the type of gas and the manifold pressure on the  
information plate located on the vestibule panel behind the upper front panel. If using the above example, the  
furnace was a CHB-100 model and the 98,663 BTUinput would be acceptable because it was within 2% of the  
listed input of 100,000.  
Make sure that the gas supply pressure to the furnace falls within the maximum range of 4 ½” to 14” wc pressure  
on natural gas and 11.0” to 14.0” w.c. on Propane gas. The pressure to the furnace must be checked while the  
furnace burner and any other gas appliances on the same supply system are operating, using the 1/8” in. plugged  
tap shown in Section III, J, Fig. 18 of this manual.  
GAS PRESSURE CHART FOR ALL CHB1 MODEL FURNACES  
TABLE 4  
SUPPLY PRESURE M A NIFOLD PRESSURE  
MAX 14" WC  
NAT  
3.5" +.3" WC  
MIN 4.5" WC  
-
MAX 14" WC  
MIN 11" WC  
LP  
10.0" + .3" WC  
-
This gas furnace is equipped with a fixed orifice sized for the manifold pressure shown on the information plate. The  
input can only be increased or decreased by adjusting the manifold pressure. Remove the 1/8" threaded pipe plug  
located on the top right side of the gas valve.  
Us a U tube manometer or pressure gage to measure the pressure. To adjust the pressure, remove the screw from the  
regulator on the outlet side of the gas valve and using the adjustment allen screw, decrease the pressure by turning  
the screw counterclockwise or increase it by turning the screw clockwise. ADJUSTMENTS TO THE LISTED  
PRESSURE MUST NOT EXCEED 0.3” w.c. A 0.3” w.c. Adjustment will increase or decrease the input  
approximately 4.0%. Replace screw (cap) when adjustment is complete.  
The correct input can be assumed if the furnace manifold pressure is the same as that shown on the information label  
if a gas meter is not available for natural gas or the unit is installed on liquefied petroleum gases which are not  
metered.  
Shut off the gas supply to the furnace. Remove the pressure gage and re-install the pipe plug using a thread  
compound resistant to the action of Liquefied Petroleum gases.  
If the rated input cannot be obtained with the present orifice at the correct pressure, your local gas supplier will assist  
in sizing the proper orifice. Our Engineering Department will gladly assist in sizing the orifice if you provide them  
with the heating value in BTU per cubic foot and the specific gravity of the gas.  
D. BURNER ADJUSTMENT  
This unit is designed to not require any burner adjustment. The flames should be checked by looking through the  
sight glass located on the burner box. Burner flames should be clear, blue and almost transparent in color. (See  
Figure 23). NOTE: It is not unusual to have orangish flames visible in the tube for Propane gas.  
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Figure 22  
: The CHB1/CDB1 furnace models are an in-shot burner design, which does not require an air  
shutter adjustment (air shutters are not used) for proper flame characteristics. Burner box access cover must  
always be secured with all screws in place and tightened before operating furnace.  
E. FURNACE CHECKOUT PROCEDURE  
Before any system of gas piping is finally put into service, it shall be carefully tested to assure that it is gas tight as  
indicated in the manual.  
NOTICE: All controls on the unit should be checked for proper functioning prior to the qualified service personnel  
leaving the job site. Specifically the following should be checked:  
With furnace in normal heating operation, check to make certain blower will start and stop automatically under  
control of integrated fan control.  
1. Check safety limit control as follows:  
a. Shut off incoming power.  
b. Block return air opening or disconnect blower motor leads.  
c. Restore power to furnace.  
d. Set thermostat above room temperature calling for heat.  
e. When temperatures are reached in furnace at limit control setting with blower out of operation, burner  
should shut off.  
f. Shut off electrical power.  
IMPORTANT: Remove blockage or reconnect blower motor and restore power.  
2. Make certain thermostat will automatically start and stop furnace.  
3. Block the flue pipe outlet gradually with a flat piece of metal, until the pressure switch functions shutting off the  
main burners.  
4. Block the PVC pipe inlet gradually with a flat piece of metal until pressure switch functions shutting off the  
main burners.  
IMPORTANT: Remove flue air inlet blockage when done.  
5. Remove the blower compartment access door with the furnace operating. The door interrupt switch is in the 120  
volt circuit and will shut down the entire system. Replace the blower door and the furnace start-up cycle will  
begin.  
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V. INSTALLER'S INSTRUCTIONS TO USER:  
After completing the installation, the installer shall inform and/or demonstrate to the homeowner:  
1. The location of all the instructions in the furnace and that these instructions and the users information manual  
must be kept along with instructions for any accessories in the plastic pouch on the inside of the furnace.  
2. The location and use of the manual gas shut off valve and furnace electrical disconnect switch. Instruct user to  
always shut off gas before shutting off electric power.  
3. The sequence of operation of the furnace.  
4. The correct operation and maintenance of the appliance as outlined in the users information manual.  
5. That failure to maintain and operate this furnace in accordance with these instructions could result in hazardous  
conditions, bodily injury, property damage and may void the limited warranty on the furnace.  
6. Review with and encourage the user to read the label reproductions and all warnings and instructions outlined on  
the front cover and in sections I, II and III of this manual and in the Users Information Manual.  
7. Recommend that the user have a qualified heating contractor inspect the furnace at the start of each heating  
season. Inform the user of the frequency of inspection required for each item in Section III of the Users Manual.  
Figure 23  
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VI. TROUBLESHOOTING  
NOTICE: BEFORE TROUBLESHOOTING, FAMILIARIZE YOURSELF WITH THE START UP AND  
CHECKOUT PROCEDURE.  
ALL INSTALLATION AND SERVICES MUST BE PERFORMED BY QUALIFIED HEATING  
CONTRACTORS.  
To assist you in troubleshooting this furnace, it is equipped with an integrated ignition control with diagnostics.  
These diagnostics evaluate what control system has experienced a failure and will activate a flashing light on the  
control in different sequences to help pinpoint the failure which has occurred.  
IMPORTANT: For your convenience, Thermo Products has installed a sight glass in the blower door of this  
furnace. The number of flashes in groups should be observed through this sight glass and recorded before turning off  
power to the furnace. Otherwise power to the furnace will be when turning off power or removing the blower door  
which is equipped with door interlock switch, which will reset the control. Should this occur, it will be necessary to  
restart the furnace and have the failure occur again.  
DIAGNOSTIC FEATURES  
The 50A65 control continuously monitors its own operation and the operation of the system. If a failure occurs, the  
LED will indicate a failure code as shown below. If the failure is internal to the control, the light will stay on  
continuously. In the case, the entire control should be replaced, as the control is not field-repairable.  
If the sensed failure is in the system (external to the control), the LED will flash in the following flash-pause  
sequences to indicate failure status (each flash will last approximately 0.25 seconds, and each pause will last  
approximately 2 seconds).  
1 flash, then pause  
2 flashes, then pause  
3 flashes, then pause  
4 flashes, then pause  
6 flashes, then pause  
7 flashes, then pause  
8 flashes, then pause  
System lockout  
Pressure switch stuck closed  
Pressure switch stuck open  
Open limit switch or rollout switch  
115 Volt AC power reversed  
Low flame sense signal  
Check ignitor or improper grounding  
Continuous flashing  
(no pause)  
Flame has been sensed when  
no flame should be present  
(no call for heat)  
The LED will also flash once at power-up.  
: Power must be disconnected before servicing.  
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TROUBLESHOOTING GUIDE  
THE SYSTEM IS STARTED BY SETTING THE THERMOSTAT TO CALL FOR  
HEAT. THE FOLLOWING SHOULD HELP ESTABLISH THE TYPE OF  
MALFUNCTION OR DEVIATION FROM THE NORMAL OPERATION.  
TO USE THIS DIAGRAM, YOU JUST NEED TO FOLLOW THE INSTRUCTIONS IN THE BOXES.  
TURN THERMOSTAT TO CALL FOR HEAT  
DOES THERMOSTAT MAKE CONTACT?  
No  
No  
No  
IS ROOM TEMPERATURE  
BELOW THERMOSTAT  
SETTING?  
IS ROOM  
TEMPERATURE  
ABOVE 90 DEGREES F?  
TURN T'STAT  
SETTING ABOVE  
ROOM TEMP.  
Yes  
Yes  
Yes  
COOL THE THERMOSTAT  
IS THE TRANSFORMER No  
SUPPLYING 24 VOLTS  
TO THE THERMOSTAT?  
No  
CORRECT WIRE  
CONNECTIONS  
ARE WIRES CONNECTED  
PROPERLY?  
Yes  
Yes  
CHECK INPUT  
POWER, DOOR  
INTERLOCK,  
SERVICE SWITCH  
AND FUSES.  
No  
REPLACE  
THERMOSTAT  
IS INTERNAL DAMAGE  
PRESENT ON THE  
TRANSFORMER?  
Yes  
Yes  
REPLACE TRANSFORMER  
No  
No  
CHECK FOR  
CONTINUITY  
& PROPER  
IS THE INDUCER  
BLOWER OPERATING?  
IS THERE 24 VOLTS  
ACROSS "TH" & "TR"  
AT THE INTEGRATED  
CONTROL MODEL?  
CONNECTIONS  
Yes  
Yes  
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Yes  
Yes  
IS THERE LINE VOLTAGE  
ACROSS INDUCER POWER  
TERMINALS "IND" & "IND N"  
AT THE INTEGRATED CONTROL?  
No  
CHECK THE INTEGRATED  
CONTROL DIAGNOSTIC LED  
LAMP. RESET BY INTERRUPTING  
POWER TO CONTROL FOR MORE  
THAN ONE SECOND. IF LED STAYS  
ON CONTINUOUSLY, REPLACE  
INTEGRATED CONTROL.  
Yes  
CHECK WIRING TO INDUCER  
AND IF OK, REPLACE  
INDUCER ASSEMBLY.  
DOES THE HOT  
SURFACE  
IGNITOR ENERGIZE  
AND GLOW?  
CHECK THE INTEGRATED CONTROL  
DIAGNOSTIC LED LAMP. RESET BY  
INTERRUPTING POWER TO CONTROL  
FOR MORE THAN ONE SECOND. IF  
LED STAYS ON CONTINUOUSLY,  
REPLACE INTEGRATED CONTROL.  
No IS THERE VOLTAGE PRESENT No  
AT THE HOT SURFACE  
IGNITOR TERMINALS  
"IGN" & "IGN N" AT THE  
INTEGRATED CONTROL?  
Yes  
CHECK WIRING TO  
HOT SURFACE IGNITOR  
AND IF OK, REPLACE  
Yes  
HOT SURFACE IGNITOR ASSEMBLY.  
CHECK ACROSS "MV"  
TERMINALS ON INTEGRATED  
CONTROL FOR 24 VOLTS DURING  
THE 4 SECOND FLAME PROVING  
PERIOD AFTER IGNITOR WARM-UP.  
IS THERE 24VOLTS?  
AFTER HOT SURFACE  
IGNITOR WARM-UP,  
DOES GAS VALVE OPEN?  
No  
No  
SAME AS ABOVE.  
Yes  
Yes  
CHECK WIRING TO GAS  
VALVE AND IF OK,  
REPLACE GAS VALVE.  
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Yes  
AFTER GAS VALVE  
OPENS, DO THE  
BURNERS IGNITE?  
No  
CHECK FOR PROPER  
MANIFOLD PRESSURE.  
ADJUST TO 3.5" FOR NATURAL GAS  
OR 10.0" WC FOR LP GAS  
Yes  
Yes  
IS IGNITOR  
No  
REPOSITION TO  
POSITIONED CORRECTLY?  
CORRECT LOCATION.  
DO BURNERS STAY  
LIT PAST PROOF  
OF FLAME CHECK?  
Yes  
DOES THE INTEGRATED CONTROL  
ENERGIZE THE  
CHECK ACROSS THE  
CIRCULATING AIR  
BLOWER TERMINALS  
"CIR N" & "HEAT"  
No  
No  
REPLACE THE  
INTEGRATED CONTROL.  
CIRCULATING AIR BLOWER  
AFTER THE 45 SECOND  
TIME DELAY.  
FOR PROPER VOLTAGE.  
Yes  
CONFIRM IF  
EITHER BLOWER WHEEL  
IS RUBBING AGAINST  
HOUSING OR MOTOR  
SHAFT IS SPINNING  
DOES THE CIRCULATING No  
AIR FAN COME ON  
No  
DOES BLOWER  
SPIN FREELY?  
WHEN ENERGIZED?  
FREELY AND REPAIR  
OR REPLACE AS NECESSARY.  
Yes  
Yes  
Yes  
IS CAPACITOR  
REPLACE MOTOR  
WORKING PROPERLY  
No  
REPLACE CAPACITOR  
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Yes  
No  
No  
DOES SYSTEM RUN UNTIL  
THERMOSTAT IS SATISFIED?  
IS LED LIGHT  
ON INTEGRATED  
CHECK ALL  
WIRING FOR  
CONTROL FLASHING?  
LOOSE CONNECTIONS.  
Yes  
Yes  
DOES BURNER SHUT OFF  
WHEN THERMOSTAT IS  
SATISFIED?  
No  
CHECK FOR SHORT IN WIRE TO  
THERMOSTAT AND CORRECT  
IF NECESSARY.  
Yes  
DOES THE CIRCULATING  
AIR BLOWER TURN OFF  
AFTER THERMOSTAT IS  
SATISFIED WITHIN  
120 SECONDS?  
Yes  
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Yes  
Yes  
IF LED LIGHT FLASHES:  
1 FLASH, THEN PAUSE  
SYSTEM LOCKOUT  
2 FLASHES, THEN PAUSE PRESSURE SWITCH STUCK CLOSED  
3 FLASHES, THEN PAUSE PRESSURE SWITCH STUCK OPEN  
4 FLASHES, THEN PAUSE OPEN LIMIT SWITCH OR ROLLOUT SWITCH  
6 FLASHES, THEN PAUSE 115 VOLT AC POWER REVERSED  
7 FLASHES, THEN PAUSE LOW FLAME SENSE SIGNAL  
8 FLASHES, THEN PAUSE CHECK IGNITOR OR IMPROPER GROUNDING  
CONTINUOUS FLASHING  
(NO PAUSE)  
FLAME HAS BEEN SENSED WHEN  
NO FLAME SHOULD BE PRESENT (NO  
CALL FOR HEAT)  
THE LED WILL ALSO FLASH ONCE AT POWER-UP.  
CHECK COMPLETE SYSTEM OUT.  
LED LIGHT STAYS ON CONTINUOUSLY,  
COMPLETE FAILURE - REPLACE  
INTEGRATED CONTROL.  
TROUBLESHOOTING COMPLETE.  
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Appendix –A Replacement Parts List  
1. Replacement parts list for CHB1-50, CHB1-75, CHB1-100 and CHB1-125.  
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2. Replacement parts list for CDB1-50, CDB1-75, CDB1-100 and CDB1-125.  
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Appendix – B Wiring Diagrams  
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