INSTALLATION AND SERVICE MANUAL
MODELS:
PGT5-100, PGT11-125, PGT16-160,
PGL20-180, PGL33-250, PGL37-312, & PGL39-400
? WARNING: 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 A QUALIFIED
HEATING CONTRACTOR).
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
MG-807C
ECN 4403-MA
MADE IN USA
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All installations and services must be performed by qualified service personnel.
This page contains reproductions of the various warning and instruction labels placed on the Thermo Pride Power Gas
Furnaces. Please read and comply with the contents of these labels.
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All installations and services must be performed by qualified service personnel.
This page contains various warnings and cautions reproduced from the Power Gas Furnace Manual. Please read
and comply with the statements below.
CAUTION: When installing the burner, it should be noted that the loose fill insulation and fiber chambers are made with
ceramic fibers. Currently, there are no known chronic health effects in humans associated with long term exposure to
ceramic fibers. The International Agency for Research on Cancer (IARC) based on its review of studies that injected
ceramic fiber into the abdomens of hamsters and rats have classified fibrous glass wool, mineral wool (both rock wool and
slag wool) and ceramic fiber as group 2B carcinogens. A group 2B agent is considered by IARC to have the possibility of
being carcinogenic to humans. IARC has also classified these fibrous materials as group 2A carcinogens when they have
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undergone long term exposure to temperatures greater than 1800 F. A group 2A agent is considered to have the probability
of being carcinogenic to humans. For these reasons, we suggest the use of a 3M 9900, 3M 8710 or equivalent mask when
working with any ceramic fiber products. For further information, contact the Manager of Customer Service for Rex Roto
Corporation at (517) 324-7533.
WARNING: This furnace is not to be used as a construction heater.
WARNING: When common venting two appliances into a common vent, the smallest appliances must be vented into the
top opening.
WARNING: A Category 1 appliance must never be connected to a chimney that is servicing a solid fuel appliance. If a
fireplace chimney, lined with a metal liner is used to vent this appliance, the fireplace opening must be permanently sealed.
WARNING: The PG Series furnaces must not be installed with a manual or thermally actuated vent damper.
WARNING: TURN OFF THE ELECTRICAL POWER to the furnace before attempting to change blower speed wiring.
WARNING: For initial start-up, of the furnace after installation, it may be necessary to purge the air out of the gas line.
This should be done by qualified service personnel. If excessive gas escapes when purging the 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 LP gas
is heavier then air allowing it to accumulate at floor level at a dangerous concentration.
WARNING: Heat exchanger paint will cure on initial firing creating an odor.
WARNING: The heat exchanger must be cleaned by a qualified service technician.
WARNING: The power gas burner has its own transformer and no other electrical equipment should be operated from this
transformer. If an electrical vent damper is used, a separate transformer and relay must be installed. Thermally actuated vent
dampers cannot be used with this power burner because the damper must be in the open position before the burner ignites.
WARNING: 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.
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All installations and services must be performed by qualified service personnel.
I. GENERAL INSTRUCTIONS
These instructions must be read in their entirety before installing the furnace. It is the installer's responsibility to do the
following:
1. Inform and demonstrate to the user, the correct operation and maintenance of the appliance.
2. Inform the user of the hazards of flammable liquids and vapors and to remove such liquids and vapors from the vicinity of
the appliance.
II. GENERAL INSTALLATION
These furnaces are shipped with the power gas burner shipped separately. For parts shortage or damage, see the Dealer
Receiving and Freight Claim Procedure Section of the price guide. After installation, the furnace and duct system must be
adjusted to obtain a temperature rise of 50°F to 80°F through the furnace. The installation must conform with local codes or
in the absence of local codes with the National Fuel Gas Codes ANSI Z223.1 LATEST EDITION and to these instructions.
WARNING: This furnace is not to be used as a construction heater.
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 to these instructions, regulations of the National Fire
Protection Association, provisions of National Electrical Code (ANSI/NFPA70 LATEST EDITION), and the National Fuel
Gas Code (ANSI Z223.1 LATEST EDITION).
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. The furnace installed is to be level in a central location with respect to outlet registers and should be located near the
chimney to minimize the numbers of elbows and the length of any horizontal run of connecting flue pipe which may be
required.
4. Definitions of "COMBUSTIBLE MATERIAL" and "NON-COMBUSTIBLE" as issued by
NFPA-Z11-1-3 is as follows:
B. CONSTRUCTION MATERIALS
a. COMBUSTIBLE MATERIAL:
Materials made of or surfaced with wood, compressed paper, plant fibers, plastics or other material that will ignite and burn
whether flameproof, fire retardant treated, or plastered.
b. NON-COMBUSTIBLE MATERIAL:
Material which will not ignite and burn; such materials consisting entirely of steel, iron, brick, concrete, slate, glass, plaster
or combination thereof.
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- MINIMUM CLEARANCES TO COMBUSTIBLE MATERIALS -
MODEL NO. FROM SIDES
OF FURNACE
FRONT
TOP & SIDES FROM THE REAR BOTTOM
OF PLENUM FLUE OR
VENT
PGT5-100
PGT11-125
PGT16-160
1 IN.
1 IN.
24 IN.
24 IN.
24 IN.
24 IN.
24 IN.
24 IN.
1 IN.
1 IN.
4 IN.
9 IN.
1 IN.
1 IN.
1 IN.
1 IN.
9 IN.
1 IN.
1 IN.
1 IN.
1 IN.
1 IN.
1 IN.
1 IN.
N/A
PGL20-180
PGL33-250
18 IN.
18 IN.
18 IN.
1 IN.
1 IN.
1 IN.
1 IN.
1 IN.
1 IN.
N/A
N/A
PGL37-312
PGL39-400
1 IN.
24 IN.
1 IN.
18 IN.
1 IN.
N/A
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".
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.
C. FURNACE LOCATION AND COMBUSTION AIR
A furnace installed in a residential garage must be installed so the burners and ignition source are located higher than 18
inches above the floor. Also, the furnace must be located or protected to avoid physical damage by vehicles. The furnace
must be located on a dry surface. If the surface becomes wet or damp at times, the furnace should be supported above the
floor using a concrete base, bricks, patio blocks, etc.
The electrical components of this furnace should be protected against water or moisture.
The area in which the furnace is located must have an adequate supply of air for combustion and draft. Open non-partitioned
basements, below grade utility room windows without storms or rooms with loose access doors will generally permit
adequate air infiltration. However, if the furnace is located in an area of the building with tight doors and windows, outside
ventilation or an opening into another room is recommended. This can be accomplished with two rectangular openings
located in a wall or door, one 6" from the ceiling or at the top of the door and one 6" from the floor or at the bottom of the
door each having a free area of not less than 1 square inch per 1,000 BTUH input but not less than 100 square inches total.
These openings must be free and unobstructed. Maintain a minimum 24" clearance to ventilation openings, which provide
combustion air to the furnace.
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EXAMPLE: 100,000 BTUH input furnaces requires "two" openings of 100 square inches each. A minimum opening of
100 square inches is required regardless of the input.
If the building is tightly constructed and or has an exhaust fan(s) that creates a negative pressure, air for combustion and
ventilation must be supplied from the outdoors or from spaces freely communicating with the outdoors. When
communicating directly with the outdoors or with vertical ducts to the outdoors, two openings each having a minimum free
area of 1 square inch per 4,000 BTU of the input rating of all gas appliances in the area are required. When horizontal ducts
are used to communicate with the outdoors, the free area must be based on 2,000 BTUH per square inch of the total input
rating of all gas appliances in the area. The minimum dimension of an air duct must be at least 4 inches in diameter.
EXAMPLE: 100,000 BTU input furnace, 40,000 BTU input water heater and 30,000 BTU gas dryer would require two
openings of 42.5 square inches each if ducted vertically to the outdoors or 85 square inches each if horizontal ducts are
used.
MAKE-UP AIR
Today's emphasis on home insulation and tightness increases the problem of air supply to the furnace. Heavy insulation cuts
off infiltration of outside air, which previously replaces inside air removed by bathroom, kitchen and laundry vent fans and
air escaping up chimneys. This tightness can cause a negative pressure condition to develop within the home. For this
reason, it is recommended that in tightly constructed and insulated homes, make-up air be provided. This can be done with
Skuttle Mfg. Co. 200 Series make-up air control. This control installs quickly and easily on any warm air heating system and
delivers controlled, fresh air automatically during the winter and summer. This type control helps solve a negative pressure
problem in a structure.
D. VENTING:
NOTICE: A draft control (double acting (MG-1) or hood type) suitable for gas firing, certified by a nationally recognized
testing laboratory and acceptable to local codes must be installed according to the control manufacturer's instructions.
The PGT and PGL series furnaces must be vented in accordance with local codes and the National Fuel Gas Code (ANSI-
Z223.1 Latest Edition) Category 1 vent tables.
The vent connector must be galvanized or stainless steel metal pipe.
The following items are requirements:
1. Flue or vent connection materials must meet requirements of all applicable local codes and the National Fuel Gas Code
(ANSI-Z223.1 LATEST EDITION).
2. A PVC pipe is not an acceptable substitute for a chimney or a flue connector. A chimney with an internal construction of
stainless steel or some other material that will withstand the flue gas temperature of 500°F is required.
3. A type B venting system as well as some masonry systems are acceptable as described in the venting tables included in
the NFGC. These venting tables also include venting combinations, which apply to common venting arrangements of two
appliances.
WARNING: When common venting two appliances into a common vent, the smallest appliance must be vented into the top
opening.
WARNING: A Category 1 appliance must never be connected to a chimney that is servicing a solid fuel appliance. If a
fireplace chimney, lined with a metal liner is used to vent this appliance, the fireplace opening must be permanently sealed.
4. The chimney height is determined by the height of the surrounding trees, roof, buildings and terrain. The chimney should
extend 24" above any surrounding obstructions.
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Trim or remove nearby trees that could interfere with chimney draft.
5. In cases where the chimney flue extends to the basement floor, the draft can usually be improved by filling the base of the
chimney with sand to within 12" of the flue pipe after relocating the cleanout cover.
6. All joints of the vent must be tightly sealed. The inside of the vent should be free of all obstructions.
7. All vents and vent connectors must fit tightly to avoid air leaks.
8. All vent connectors connecting the furnace to the vent must be rigidly supported with hangers and straps, in order to
prevent movement after installation. The vent connector must be supported every four feet for the design and weight of the
material used, to maintain clearances, and to prevent physical damage.
9. Vent connectors used in connecting the furnace to the vent cannot be channeled through floors, ceilings, and walls
without the proper protective construction. This construction must be in accordance with the requirements of the National
Fuel Gas Code (ANSI Z223.1 LATEST EDITION).
10. All single wall vent connectors connected to the PGT & PGL Series furnaces must have all seams and joints sealed with
high temperature pressure sensitive aluminum tape or silicone rubber sealant.
EXAMPLE:
1. High temperature aluminum tape, temperature rating of 400°F or more.
2. Dow Corning RTV-732 rubber sealant or equivalent.
Temperature rating of 450°F or more.
11. Vent connectors installed in or passing through an unheated space must be insulated with 1.0" thick foil faced fiberglass
or its equivalent to prevent condensate from forming in the connector or vent.
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NOTE: If this furnace replaces an appliance with a vent that was originally installed in a common vent system serving other
appliances, the vent system is likely now too large to properly vent the remaining appliances only and must be modified
accordingly. Refer to Natural Fuel Gas Code Appendix G Category I vent tables for common venting a PG Series furnace
and another fan assisted or natural draft unit.
In order too common vent a PG Series furnace with a natural draft gas fired hot water heater; follow the recommendation of
the NFGC Category I venting tables.
If the NFGC venting tables do not apply to a specific common venting system then refer to the section on replacing an
existing furnace from a common vent in Section G of this manual.
NOTICE: Thermo Pride power gas units may be sidewall vented with a power sidewall venting system that is appropriate
for the application and certified by a nationally recognized testing agency for use with gas fired warm air central furnaces.
NOTICE: An agency approved gas barometric control or draft diverter must be installed. The draft control device must
also meet the approval of the local authorities. See the draft control manufacturers instructions for installation.
E. VENT DAMPERS
If a vent damper is installed, it must be certified by a nationally recognized testing agency. It must be an electro-
mechanical type that opens completely before gas flows to the main burner and closes only after the gas valve has
shut off gas flow to the main burner.
WARNING: The PG Series furnaces must not be installed with a manual or thermally actuated vent damper.
F. CONDENSING IN THE CHIMNEY:
Due to the increasing efficiencies of our furnaces, more heat is being placed into the home instead of up the chimney.
This means that the stack temperature will be lowered which may result in condensing within the chimney under
certain conditions. The following is an explanation on why and what to do if condensing occurs.
Moisture occurs in flue gases when hydrogen is mixed with oxygen from the chemical reaction produced by
combustion. This mixture of hydrogen and oxygen produces water molecules.
The flue gas vapor may do one of two things as it escapes up the chimney:
1. Remain in a vapor state if the internal chimney wall temperature is above the dew point, or
2. Condense on the chimney walls if they are chilled below the dew point.
Condensing will always occur on chimney walls whose temperatures are below the dew point, but will evaporate
once the walls are warmer than the dew point. If the chimney walls do not reach the dew point during the cycle of the
furnace, the moisture may accumulate in large enough quantities to cause problems such as corrosion of the chimney
or corrosion of the heat exchanger.
This condensation most likely will not occur at the bottom of the chimney, because the flue gas is heating the
chimney walls as it rises and the bottom will be heated first. This heating of the walls will cause the flue gas
temperature to drop, which in turn may reduce the wall temperature below the dew point causing condensation to
appear on the upper part of the chimney first. This condensation may drip back as far as the flue pipe and heat
exchanger, where corrosion may occur if not treated.
To prevent condensation, it is necessary that the internal chimney wall temperature always be kept above the dew
point. The chimney may have to be lined with a flue liner if the temperature loss is too great for the furnace. A liner
will act as an insulator and reduce the flue gas temperature loss. Insulation may be added around the liner for further
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temperature stability. If the chimney is on the homes exterior and condensing occurs, the chimney may be insulated
around its exterior to help the flue hold its temperature. Also, check to see if the chimney is too large for the flue
gases to heat, if so reduce to proper size by lining. Be sure to use stainless steel liners such as types 430, 304 or for
the toughest corrosion resistant type 316. If the chimney is the correct size for the unit and condensing still occurs
then further insulating of the chimney must occur or the efficiency of the furnace may have to be reduced to raise the
chimney temperature.
More detailed information may be obtained from the current ASHRAE Equipment Handbook.
G. REPLACING AN EXISTING FURNACE FROM A COMMON VENT
When an existing furnace is removed from a common vent serving other appliances, the vent system is likely too
large to safely vent the remaining attached appliances. If only two appliances remain on the venting system, then the
system may be sized with the venting tables in the NFGC of this manual. If more than two appliances remain, then
the following steps shall be followed with each appliance remaining connected to the common venting system placed
in operation, while the other appliances remaining connected to the common venting system are not in operation.
a. Seal off any unused opening(s) in the common venting system.
b. Visually inspect the venting system for proper size and horizontal pitch and determine there is no blockage or
restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.
c. Insofar as is practical, close all building doors and windows and all doors between the space in which the
appliances remaining connected to the common venting system are located and other spaces of the building. Turn on
clothes dryers and any appliance not connected to the common venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan.
Close fireplace dampers.
d. Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so appliance
will operate continuously.
e. Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the flame of a
match or candle or smoke from a cigarette, cigar or pipe.
f. After it has been determined that each appliance remaining connected to the common venting system properly
vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas-
burning appliance to their previous conditions of use.
g. If the improper venting is observed on any of the appliances during the above testing, the common vent system
must be corrected. Follow the steps outlined in the National Fuel Gas Code, NFPA 54/ANSI Z223.1-LATEST
EDITION to resize the vent system. The National Fuel Gas Code may be obtained by writing the American Gas
Association Laboratories, 8501 East Pleasant Valley Road, Cleveland, OH 44131 or the National Fire Protection
Association, Battery march Park, Quincy, MA 02269.
H. GENERAL GAS PIPING
WARNING: 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.
All gas piping and testing must be performed by a qualified installer or service person. The installation must comply
with local codes, these instructions and The National Fuel Gas Code NFPA54/ANSI Z223.1-LATEST EDITION.
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Piping from the natural gas meter to the furnace shall be in accord with requirements of the local
utility. Piping from the LP tank to the furnace must follow the recommendations of the gas supplier.
1. A readily accessible, certified manual shut off valve with a non-displaceable rotor member should be installed
within six feet of the gas equipment it serves. A union or flanged connection shall be provided downstream from the
manual valve to permit removal of controls. A 1/8" N.P.T. plugged tapping, that is accessible for connecting a test
gage, must be installed immediately upstream of the gas connection to the furnace. Unions must be of a ground joint
type or flanged-joint using a gasket resistant to LPG. Pipe dope or tape certified to be resistant to the action of
liquified petroleum gases should be used on all threaded joints.
2. A drip leg must be used on both LP and natural gas installations prior to the furnace to trap oil, condensate and
other impurities which might otherwise lodge in the gas valve or plug the burner orifice. When there is excessive
condensation between the gas meter and the furnace, a drip leg shall be provided at the outlet of the gas meter.
Failure to install a drip leg may void the limited warranty on the furnace.
NOTE: All gas piping must be leak tested using a soap and water solution (if the gas is turned on) following the
procedure outline in this section (caution must be taken not to wet electronic components). A final test for gas
leakage must be made after purging the gas line. 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.
IMPORTANT: 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. If wetting occurs, dry moisture from all leads,
terminals, and electronic components using a hair dryer or similar means or wait at least 24 hours for the circuit to
fully dry before energizing the burner circuit.
The furnace and its individual gas valve must be disconnected from the gas supply during pressure testing of the gas
supply system at pressures in excess of 1/2 PSIG or 14.0" wc.
I. INSTALLATION OF NATURAL GAS PIPING
The installation of the gas piping and the following test procedures must be performed by a qualified installer or
service person.
1. The following chart is to be used as a guide in sizing natural gas supply piping. The input loading of all gas
appliances installed on any main or trunk line must be totaled to determine its needed carrying capacity.
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EXAMPLE: A line must supply a furnace of 110,000 BTU/hr input, a hot water heater of 40,000 BTU/hr input and
gas range with a 30,000 BTU/hr input capacity. The total BTU/hr input loading on the line is 180,000 BTU/hr. The
200,000 BTU/hr column on the chart must be used in sizing the pipe.
- BLACK PIPE SIZE FOR NATURAL GAS -
┌─────────────┬────────────────────────────────────────────────┐
│BURNER FIRING│
FEET OF PIPE FROM METER TO BURNER
20' 30' 40' 50'
│
│
│RATE, BTU/HR │10'
├─────────────┼─────────┬─────────┬─────────┬─────────┬────────┤
│50,000
├─────────────┼─────────┼─────────┼─────────┼─────────┼────────┤
│100,000 │3/4 │3/4 │3/4 │3/4 │1
├─────────────┼─────────┼─────────┼─────────┼─────────┼────────┤
│150,000 │3/4 │1 │1 │1 │1-1/4
├─────────────┼─────────┼─────────┼─────────┼─────────┼────────┤
│200,000 │1 │1 │1-1/4 │1-1/4 │1-1/4
├─────────────┼─────────┼─────────┼─────────┼─────────┼────────┤
│250,000 │1 │1 │1-1/4 │1-1/4 │1-1/4
├─────────────┼─────────┼─────────┼─────────┼─────────┼────────┤
│1/2
│1/2
│3/4
│3/4
│3/4
│
│
│
│
│
│300,000
│1
│1
│1-1/4
│1-1/4
│1-1/4
│
└─────────────┴─────────┴─────────┴─────────┴─────────┴────────┘
Use black iron steel pipe and malleable iron fittings for Natural gas service lines. Provide rigid supports for the pipe.
If the pipe size must be reduced, use reducing couplings only. Avoid the use of reducing bushings. Remove all burrs
and inspect the pipe for dirt or other foreign material prior to connecting.
Maximum supply pressure for natural gas is 14" wc and minimum supply for purpose of input adjustment is 5-1/2"
wc.
J. INSTALLATION OF LIQUIFIED PETROLEUM GAS (LP) PIPING
1. Experience has proved that the pressure drop in the gas line running from the outside propane gas tank to the gas
appliances in a home, is the most frequent cause of equipment malfunctions. A single pressure regulator, located at
the tank, will not reliably regulate the high tank pressures (up to 200 lbs.) down to 11" wc. Varying pressures will
occur at the appliances as outside temperatures and usage demands vary. Two stage regulations are the only effective
method of controlling these variables.
TYPICAL PIPING FOR TWO STAGE REGULATION
NOTE: Two stage regulation must be installed for liquified petroleum gas when used with any Thermo Pride LP
furnace. See illustration above of a typical two stage piping system.
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- COPPER TUBING SIZE FOR LIQUIFIED PETROLEUM GASES -
All black pipe sizes shown are I.D.
Seamless copper tubing may only be used with gases that are not corrosive to it. See note below and check with your
LP gas supplier before using. Seamless copper tubing must comply with standard type K or L for seamless copper
water tube, ASTM B 88; or seamless copper tube for air conditioning field service, ASTM B 280.
NOTE: Copper and brass tubing and fittings (except tin lined) shall not be used if the gas contains more than a trace
(0.3 grains per 100 cubic ft.) of hydrogen sulfide gas.
Maximum supply pressure for liquified petroleum (LP) gas is 14" wc and minimum supply for purpose of input
adjustment is 11" wc.
K. BURNER INSTALLATION
The power gas burner will mount on three stud mounting bolts on the lower mounting plate covering the opening in
the front of the heat exchanger. The end of the burner tube must be inserted no further than 1/4 inch back from the
inside surface of the combustion chamber to ensure proper operation and performance.
NOTE: OVERFIRE AIR TAP IS LOCATED ON LEFT SIDE OF FLAME INSPECTION COVER.
(TOP VIEW)
BURNER INSERTION
ILLUSTRATION (PGL)
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TWO PIECE MOUNTING PLATE
When mounting the burner, the upper mounting plate must be removed to provide access to the area in front of the
combustion chamber. The combustion chamber can then be moved forward or backward slightly to allow for
adjustment in positioning the burner tube. Do not allow the burner tube or end cone to physically touch the chamber,
as excessive heat transfer could result in distortion of the tube or end cone, or both.
Once the burner tube is properly positioned, at most 1/4 inch back from the inside surface of the combustion
chamber wall, the loose-fill insulation that is included should be lightly placed around the burner tube between the
front of the combustion chamber and the burner mounting plate. (DO NOT PACK THE INSULATION DOWN).
The loose-fill insulation should be placed in such a fashion that the surface of the insulation is sloped from the top of
the combustion chamber to the top of the lower mounting plate. The purpose of the loose insulation is to help protect
the burner tube, mounting plates and vestibule area from internal temperatures.
NOTE: Do not place loose insulation around chamber sides and back.
(SIDE VIEW)
BURNER INSERTION
ILLUSTRATION (PGT)
CAUTION: When installing the burner, it should be noted that the loose fill insulation and fiber chambers are made
with ceramic fibers. Currently, there are no known chronic health effects in humans associated with long term
exposure to ceramic fibers. The International Agency of Research on Cancer (IARC) based on its review of studies
that injected ceramic fiber into the abdomens of hamsters and rats have classified fibrous glass wool, mineral wool
(both rock wool and slag wool) and ceramic fiber as group 2B carcinogens. A group 2B agent is considered by IARC
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to have the possibility of being carcinogenic to humans. IARC has also classified these fibrous materials as group 2A
0
carcinogens when they have undergone long term exposure to temperatures greater than 1800 F. A group 2A agent
is considered to have the probability of being carcinogenic to humans. For these reasons, we suggest the use of a 3M
9900, 3M 8710, or equivalent mask when working with any ceramic fiber products. For further information, contact
the Manager of Customer Service for Rex Roto Corporation at (517) 324-7533.
HORIZONTAL FURNACE POSITIONS:
The horizontal furnace may be turned end for end, or rotated, making the top into the bottom, as shown below.
After the furnace has been positioned, the bottom burner mounting stud must be removed before mounting the
burner. Also, the fan & limit and its mounting bracket must be properly positioned once the unit is in place. (See
section N on fan & limit position and location).
MIDCO RE32 BURNER ADJUSTMENT
In order to properly set-up a furnace with a Midco RE32 burner,Thermo Pride’s recommendation is to utilize a
Modified version of Midco’s instruction together with combustion equipment and a carbon monoxide detector. It
must be emphasized that the gas equipment is operating properly and safely requires combustion equipment and a
carbon monoxide detector.
1. Check unit for signs of sooting and clean as necessary, the furnace heat exchanger, flue, and chimney.
2. Open the air adjustment completely. Turn adjustment screw counterclockwise until it stops.
3. To achieve a starting point for proper combustion, adjust the air adjustment screw according to the chart below
For the applicable Thermo Pride furnace utilizing the Midco RE32 burner.
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Furnace Model
** PGL16-160 Nat
PGL16-160 LP
PGL20-180Nat
PGL20-180 LP
AGL16-160LP
AGL20-180Nat
AGL20-180LP
Orifice Size
#J (.277)
#8(.199)
#J(.277)
#3(.213)
#8(.199)
#J(.277)
#3(.213)
Manifold Gas Pressure
No. Turns Closed*
2.4” W.C.
2.9”
24
24
20
20
24
20
20
3.0”
3.0”
2.9”
3.0”
3.0”
*Air Adjustment screw: Number of turns closed from the fully open position.
**PG-160 or PG-180 Power Gas Conversion Burners- use chart for applicable settings.
4. Attach a manifold pressure gauge (Inches of W.C. scale) to the outlet of the gas valve.
5. Turn on the furnace and adjust the manifold pressure to the setting indicated above for the desired rate and
orifice which applies to the unit being tested.
6. Let the furnace run until warm, approximately 10 minutes. Note: If the furnace required cleaning, you may
wish to allow any residual dust or soot to burn off before taking measurements.
7. If the draft exceeds the recommended maximum of .1”, a draft regulator should be used to reduce the draft to
the recommended parameters of –01 W.C. to –1” W.C.
8. IMPORTANT: An accurate CO2 or O2 combustion analyzer is required when setting combustion. A carbon
monoxide detector capable of measuring flue gas down to 50 PPM of CO is also required. After the unit has
operated a minimum of 10 minutes and a proper draft is established-between-.01” W.C. and -.1” W.C., perform
a combustion test and make final adjustment to the combustion air to achieve the CO2 or O2 as listed below.
NATURAL GAS
MIN.
7.0%
2.0%
MAX.
11.0%
8.9%
CO2
O2
CO
<50 PPM
<50PPM
L.P. GAS
MIN.
MAX. **See
CO2
O2
8.0%
10.4% Note Below
8.9% **See Note Below
5.5%
CO
DRAFTOVERFIRE
MIN.
-.01
.MAX.
-.1
**Note!! Under absolutely no circumstances should the air adjustment screw (on LP units only) be closed more than
the number of turns indicated by the chart on the previous page.
9. Once the CO2 or O2 is adjusted to the above parameters, a Carbon Monoxide test must be done to insure less
than 50 PPM in the flue gas.
Any sign of soot or carboning during combustion indicates that there is insufficient primary air and the air shutter
should be opened more until this condition is corrected. If soot or carboning of the burner is suspected, a smoke
sample should be taken after the burner operates a minimum of 10 minutes. This would typically only occur in the
LP units. Opening the air adjustment screw should reduce the carboning from the combustion process.
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In summary, setting the combustion air on the Thermo Pride Midco RE32 power gas conversion burner is
extremely critical. This adjustment should only be made by following these instructions and confirming the
set-up with the proper CO2 or O2 combustion analyzer and a carbon monoxide reading of less than 50 PPM.
L. 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 a return air register is located in the same room as the furnace, it must be installed a minimum of 20 feet
away from the furnace.
2. If supply ducts carry circulated air to areas outside the space containing the furnace, the return air duct shall also
be sealed to the furnace and also terminate outside of the furnace space.
3. The return air duct system must equal the supply air duct system in its CFM 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.
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 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.
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. 1.4 CFM of heating per 100 BTU's of furnace output based on its steady state efficiency and a 50° to 80°
temperature rise.
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EXAMPLE: Heating output of furnace is 100,000 x 1.4 ÷ 100 = 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 BTU's of cooling x 400 CFM = 1200 CFM was installed, the duct would have to be
sized for the 1400 CFM heating requirement.
To insure obtaining the necessary air handling capacity of a duct system, each of the system components (trunk lines,
take offs, runs and register and grill-free areas) must be properly sized and matched together. A 12"x8" 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.
To achieve proper air movement, 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. The chart shows the CFM air-handling
capability based on a 0.1" SP loss, in the supply duct system.
DUCT SIZES FOR HOMES, QUIET OFFICES OR SIMILAR INSTALLATIONS
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DUCT WORK/AIR CONDITIONING:
If the furnace is used in connection with summer air conditioning (cooling), the furnace should be installed parallel
with or on the upstream side of the evaporator coil to avoid condensation in the furnace heat exchanger. If the
cooling unit is installed with a parallel flow arrangement, dampers or other means used to control flow of air should
be provided to prevent chilled air from entering the furnace. If such a damper is manually operated, it must be
equipped with a means to prevent operation of either unit, unless the damper is in the full heat or cool position.
The duct system should again follow the design standard of Air Conditioning Contractors of America (ACCA) or
ASHRAE. (Latest Edition Fundamentals Volume).
A slab coil (HE style) is available for the horizontal air flow application on the PGT5-11-16 furnaces. (See Fig.
below).
To obtain proper CFM with air conditioning installed on a belt drive unit, the motor and/or blower pulley may need
to be changed. On a direct drive unit the blower motor speed may need to be changed depending upon the size of the
air conditioning system installed and the static resistance of the duct system.
NOTE: The horizontal units have direct drive blowers and no pulley or motor change is required. See direct drive
motor and blower specifications for air conditioning CFM's at .5 static.
SIZING THE DUCT WORK FOR A COMBINATION HEATING AND COOLING SYSTEM:
Two formulas must be used in determining the CFM requirements of a combustion heating and cooling system.
1. HEATING CFM:
BTU'S OUTPUT OF FURNACE
1.1 X TR (TEMPERATURE RISE) = HEATING CFM
EXAMPLES:
A. 110,000 BTU OUTPUT
0
1.1 X 85 F TR = 1176 CFM FOR HEATING
B. 110,000 BTU OUTPUT
0
1.1 X 70 F TR = 1429 CFM FOR HEATING
2. COOLING CFM: 400 CFM X COOLING TONNAGE (12,000 BTU PER TON) =
CFM FOR COOLING
EXAMPLES:
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A. 400 CFM X 3 TON (36,000 BTU'S) = 1,200 CFM FOR COOLING
B. 400 CFM X 2.5 TON (30,000 BTU'S) = 1,000 CFM FOR COOLING
NOTE: To obtain the proper 50°F to 80°F temperature rise for heating an air conditioning coil is installed, the speed
of the blower motor may have to be changed. This depends on the static resistance of an individual duct system and
the size of the air conditioner.
M. FILTERS
To clean a dirty filter, first remove the blower compartment door. Remove dirty filter from the filter rack and clean
with a mild soap and water solution. Make sure filter is thoroughly dry before replacing. Put blower compartment
door back into place.
A. PGT HORIZONTAL UNITS
B. PGL LOWBOY
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N. FAN AND LIMIT POSITION AND LOCATION
Power gas furnace models PGL5 through PGL20 are shipped with the fan and limit control pre-mounted in the
vestibule. Should the installer prefer to mount the fan and limit control in the supply plenum, the installer must
supply additional wire comparable to the original wire size and type which must be routed through either rigid, EMT
or flexible metal conduit to the mounting location as described below.
LOCATION FOR LOWBOYS & HORIZONTALS
WITHOUT AIR CONDITIONING:
FAN & LIMIT LOCATION FOR HORIZONTALS
WITH AIR CONDITIONING:
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A. FAN & LIMIT LOCATION WITH H-COIL:
The fan & limit control should be mounted between the H-coil cabinet and furnace. For distances from top of plenum
and furnace, see chart above. IMPORTANT: Do not mount fan/limit in H-coil cabinet.
O. WIRING
All wiring must conform to the provisions of local codes or in the absence of these codes with the provisions of the
National Electrical Code, ANSI/NFPA70 (Latest Edition).
The following items are guidelines to complete the wiring portion of the installations.
1. Install the room thermostat according to instructions provided with thermostat. Set the anticipator to .8 amps.
2. The furnace must be grounded in accordance with local codes and with the National Electrical Code,
ANSI/NFPA70 (Latest Edition).
WARNING: TURN OFF THE ELECTRICAL POWER to the furnace before attempting to change blower speed
wiring.
WARNING: The power gas burner has its own transformer and no other electrical equipment should be operated
from this transformer. If an electric vent damper is used, a separate transformer and relay must be installed.
Thermally actuated vent dampers cannot be used with this power burner because the damper must be in the open
position before the burner ignites.
For information on the electrical internal workings of the burners itself and the procedure for "initial start-up" and
"adjustment" of the power burner, reference power burner manufacturer's instructions.
All wiring must perform to provisions of the National Electrical Code ANSI/NFPA70 (Latest Edition). Wiring
between the furnace and devices that are field installed shall conform to temperature limitations for type T wire (35
C rise) and Local Ordinances. If any of the original wire supplied with the unit needs to be replaced, 105°C
thermoplastic or its equivalent, must be used. The power supply to the furnace is to be on an individual electrical
circuit with properly sized over-current protection.
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All electrical wiring must be installed in strict accordance with local ordinances and codes. In the absence of local
ordinances and codes, all electrical wiring must be in accordance with the National Electrical Code (ANSI/NFPA 70-
LATEST EDITION).
On the following pages are the wiring diagrams for the various Thermo Pride gas furnace models.
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Wiring:
All electrical wiring must be installed in strict accordance with local ordinances and codes. In the absence of local
ordinances and codes, all electrical wiring must be in accordance with the National Electrical Code (ANSI/NFPA 70-
LATEST EDITION).
Below and on the following pages are the wiring diagrams for the various Thermo Pride gas furnace models.
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II. STARTING THE UNIT
A. INITIAL START UP:
1. Check all wiring for loose connections and proper hook up.
2. Leak test gas piping connections.
3. Check tubing to the pressure switch to make sure it is pushed firmly onto the pressure tap.
4. Check flue pipe, chimney, and all connections for tightness and to make sure there is no blockage.
5. Make sure air filters are in place.
OPERATING INSTRUCTIONS:
WARNING: For initial start-up of the furnace after installation, it may be necessary to purge the air out of the gas
line. This should be done by qualified service personnel. If excessive gas escapes when purging the supply at the
union, allow the area to ventilate for at least 15 minutes before starting the furnace. LP gas is especially hazardous
because the specific gravity of LP gas allows it to accumulate at floor level at a hazardous concentration.
WARNING: Heat exchanger paint will burn off on initial firing creating an 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 remains running at conditions 1 & 2 for 30 minutes or until the odor has dissipated.
B. BURNER COMBUSTION:
Obtain the following recommended values when setting the burner combustion:
CO NATURAL GAS - MIN. 8.5%, MAX. 10.5% WITH NO MORE THAN 50 *PPM OF CO.
2
CO LPG - MIN. 10.5% MAX. 12.0% WITH NO MORE THAN 50 *PPM OF CO.
2
CO ALL GASES - ZERO TO A MAX. 50 *PPM.
After final adjustments are made, lock settings to prevent tampering.
*PPM = PARTS PER MILLION
50 PPM = .005% = 1/200 OF 1%
NOTICE: See burner manufacturer instructions for troubleshooting.
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 .60 or 2. For liquified propane gas with a heating value of 2500 BTU per cubic foot and a specific
gravity of 1.53. 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
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elevation of 2,000 feet or less, no reduction in input is required. Your gas supplier will supply you with the correct
BTU and orifice sizing information.
To check the input of your natural gas furnace, proceed as follows:
a. Call your gas supplier and ask for the BTU content (heating valve) 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 that is the national average.
b. With all other gas appliances turned off, allow the unit to operate for 10 to 15 minutes. 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 are flowing for each revolution usually one, two or five. The unit must have been in operation at least 10
minutes before clocking.
FORMULA: BTU/Cu Ft x Number of Cu Ft x 3600 Seconds = Input
BTU/hr
Seconds for one revolution
EXAMPLE: 1025 BTU/Cu Ft x 2 Cu Ft x 3600 = 98.663 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
PGT5-100 model the 98,663 BTU input would be acceptable because it was within 2% of the listed input of
100,000.
c. Make sure that the gas supply pressure to the furnace falls within the maximum range of 5-1/2" to 14" WC
pressure on natural gas and 11.0" to 14.0" WC on LP gases. 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 test procedure
outlined in Section H of this manual.
This gas furnace is equipped with a fixed orifice sized for the manifold pressure shown in the burner manual. The
input can be increased or decreased by adjusting the manifold pressure. Remove the 1/8" threaded pipe plug located
on the bottom right side of the gas valve. Use a U tube manometer or pressure gage to measure the pressure. To
adjust the pressure, remove the cap from the regulator on the top of the gas valve and using the adjustment 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 the recommended maximum manifold
pressures in the burner manual.
If a gas meter is not available for natural gas, or the unit is installed on liquified petroleum gases which are not
metered, the correct input can be assumed if the furnace manifold pressure is the same as that shown on the
information label and the orifices are sized correctly.
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 LP 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.
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ORIFICE CHART
FURNACE
MODEL NO.
L.P.
NAT.
PGT5-100
.113 OR #33 DMS
.1285 OR #30 DMS
.144 OR #44 DMS
.213 OR #3 DMS
.265 OR 17/64 DMS
.297 OR 19/64 DMS
.332 OR Q DMS
.196 OR #9 DMS
.213 OR #3 DMS
.238 OR B DMS
.277 OR J DMS
PGT11-125
PGT16-160
PGL20-180
PGL33-250
PGL37-312
PGL39-400
.332 OR Q DMS
.390 OR 25/64 DMS
.468 OR 15/32 DMS
D. 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 Gas Piping Section of Burner 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 fan switch.
a. Check safety limit control as follows:
1. Shut off incoming power.
2. Block return air opening or remove blower belt on belt drive or unplug blower at terminal strip on direct drive.
3. Restore power to furnace.
4. Set thermostat above room temperature calling for heat.
5. When temperatures are reached in furnace at limit control setting with blower out of operation, burner should be
shut off.
6. Shut off electrical power, remove blockage and restore power.
b. Make certain thermostat will automatically start and stop the burner and fan control operates blower properly.
IV. INSTALLER'S INSTRUCTIONS TO USER:
After completing the installation, the installer shall inform and demonstrate to the homeowner: 1. The Sequence of
Operations. 2. Operating Instructions and Routine Maintenance. 3. Review label reproductions at beginning of this
manual.
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V. DEALER MAINTENANCE
A. ELECTRICAL:
1. Check all wiring for loose connections.
2. Check for correct voltage at the furnace when operating.
3. Check amp-draw on blower motor and burner to assure they are not exceeding name plate amp rating.
B. CLEANING HEAT EXCHANGER:
WARNING:
THE HEAT EXCHANGER MUST BE CLEANED BY A QUALIFIED SERVICE
TECHNICIAN.
It is important to inspect and clean the heat exchanger once a year or as necessary to remove any build-up of soot. A
layer of soot on the inside of the heat exchanger will act as an insulator and reduce heat transfer, resulting in less
efficiency. If heavy soot deposits were found in the heat exchanger, this indicates that the burner may be out of
adjustment. Reset the burner as indicated under the "BURNER COMBUSTION" section.
To clean the heat exchanger, first turn off all power to the unit. Next, remove the access panel (see below and
following page) immediately above the burner (on the horizontal furnace, it will be located to the side of the burner)
to gain entry to the cleanout covers. (Please notice: This panel is identified with a label.) Remove cleanout
covers, the vent connector pipe to the chimney, the burner, and the burner mounting plates. When removing the
cleanout covers, special care must be taken not to damage the gaskets. Should the gaskets separate, crack, break, or
otherwise not be able to provide the necessary seal, the gasket must be replaced before reattaching the cleanout
covers.
With access to the inside of the heat exchanger through the burner area, cleanout openings, and vent pipe connection,
it is now possible to use a long, flexible wire brush and an industrial type vacuum cleaner to remove any soot build-
up. NOTE: A one inch (outside diameter) vacuum cleaner hose will fit into the outer radiator.
To vacuum and brush the outer radiator of the heat exchanger, go through the cleanout openings in both directions,
as shown below.
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Reassemble the furnace to its original construction. Remount the burner being certain that the air tube is properly
inserted into the chamber opening (see Burner Installation section).
VI. TROUBLESHOOTING
For troubleshooting the power gas burner, reference the burner manufactures instructions.
If the burner is producing an excessive combustion sound level, perform the following procedures:
1. Re-check the position of the burner tube to assure that the end of the tube is 1/4 inch in from the inside surface of
the combustion chamber. Also, make sure the burner is firing squarely into the center of the combustion chamber.
2. Verify the correct burner air setting using instrumentation (see initial start up section). If the air setting on the
burner is excessive, this will cause the combustion sound level to be louder than normal.
3. Move the draft control as close to the chimney as possible. Also, face the draft control towards the open area of
the room.
4. Alter manifold pressure of the burner, but stay within normal operating pressures as specified by burner
manufactures instructions.
5. Derate the input of the burner 10% from normal furnace input rate.
6. If the combustion sound is resonating through a particular portion of the ductwork, insulating the ductwork or
using flex duct should isolate that portion of the ductwork.
If the furnace air blower will not come on or cycles abnormally, check the following:
1. If the blower motor is receiving 115 V, it has cutout on thermal overload or is defective. A belt that is very tight
may cause the blower motor to cut out on thermal overload on a belt drive blower. An incorrect or faulty capacitor
may prevent a direct drive blower motor from operating.
2. If the blower motor is not receiving 115 V, check the power source to the furnace, as well as all wire connections
in the vestibule junction box. Check wire connections at the fan and limit and the fan temperature settings. Also,
check the fan and limit for response to temperature.
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VII. REPLACEMENT PARTS
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