Thermo Products Pride Furnace Cma3 50D36N Users Manual

CMC1-75DV3N to the manual 30eb0262-3082-4f5f-ad96-98e4dd837e61

2015-02-03

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GAS FIRED HIGH EFFICIENCY FURNACE
DOWNFLOW & DIRECT VENT (SEALED COMBUSTION)
MODELS:
CMA3-50D36N, CMA3-75D36N,
CMC1-50D36N, CMC1-75D36N,
CMC1-50DV3N, CMC1-75DV3N
INSTALLATION AND SERVICE MANUAL
For installation in:
1. Manufactured Homes
2. Modular Homes/Buildings
3. Site Constructed—Residential (Single Story Dwellings)

FOR YOUR SAFETY
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.
• 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.

: If the information in these instructions is not followed exactly, a fire or explosion may
result causing property damage, personal injury, or loss of life.
: Improper installation, adjustment, alteration, service, or maintenance can cause injury or
property damage. Refer to this manual. For assistance or additional information, consult a qualified
installer, service agency, or fuel supplier.
: 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 electrical or control system
that has been underwater.
PLEASE READ THESE INSTRUCTIONS PRIOR TO INSTALLATION, INITIAL FIRING, AND BEFORE PERFORMING
ANY SERVICE OR MAINTENANCE. THESE INSTRUCTIONS MUST BE LEFT WITH THE USER AND SHOULD BE
RETAINED FOR FUTURE REFERENCE BY QUALIFIED SERVICE PERSONNEL.

THERMO PRODUCTS, LLC.
POST OFFICE BOX 217
NORTH JUDSON, IN 46366
PHONE: (574) 896-2133
MG-517
ECN 5295-MA 140106

MADE IN USA

TABLE OF CONTENTS
SECTION
I. SAFETY INFORMATION
II.

BEGINNING PAGE
1

FURNACE SPECIFICATIONS

III. GENERAL INSTRUCTIONS AND CLEARANCES

IV. GENERAL INSTALLATION
A. FURNACE LOCATION
B. BASE INSTALLATION
C. ALCOVE INSTALLATION
D. CLOSET INSTALLATION
E. FUEL PIPING
F. GENERAL VENTING REQUIREMENTS
G. CONNECTING THE EXHAUST VENT, AND COMBUSTION
AIR INTAKE
H. DIRECT VENTING THROUGH A SIDEWALL
I. INSTALLATION OF OUTSIDE EXHAUST/INTAKE TERMINATIONS
J. CONNECTING THE FURNACE TO ROOF VENT/ INTAKE TERMINATIONS
K. CONDENSATE DRAIN LINE AND TRAP ASSEMBLY
L. ELECTRICAL WIRING

13
13
15
16
14
19
20
22

41
41
43
44
45
46
47

STARTING THE UNIT
A. SEQUENCE OF OPERATION
B. INITIAL START-UP
C. ADJUSTMENT OF BTU INPUT RATE
D. BURNER ADJUSTMENT
E. SETTING TEMPERATURE RISE
F. FURNACE CHECK-OUT PROCEDURE

24
27
28
30
31

VI. INSTALLER'S INSTRUCTIONS TO USER

VII. DEALER MAINTENANCE
A. ELECTRICAL
B. GENERAL INSPECTION
C. HEAT EXCHANGER
D. HOUSE AIR BLOWER
E. RETURN AIR FILTER

48
49
49
50
50
50

VIII. TROUBLE SHOOTING

APPENDIX-A
APPENDIX-B

58
62

REPLACEMENT PARTS
WIRING DIAGRAM

REFERENCED PUBLICATIONS:
NATIONAL FUEL GAS CODE
NFPA 54/ANSI-Z233.1
(LATEST EDITION)

FOR COPIES CONTACT:
NATIONAL FIRE PROTECTION ASSOCIATION
1 BATTERYMARCH PARK
P.O. BOX 9101
QUINCY, MA 02269-9101

All installations and services must be performed by qualified service personnel.

I. SAFETY INFORMATION
This and the following 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.

All installations and services must be performed by qualified service personnel.

This and the previous page contain reproductions of the various safety and instruction
labels placed on the Thermo Pride Condensing Gas Furnaces. Please read and comply
with the contents of these labels.

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. Do not install this furnace where it could be exposed to drafts or other wind or
moisture conditions. Refer to Section IV of this manual.
3. Provide adequate ventilation air to the furnace space. Refer to Section IV, C and D,
of this manual.
4. Connect this furnace to an approved vent system only. Combustion products must
be carried outdoors. Refer to Section IV, F thru J, of this manual.
5. Never test for gas leaks with an open flame. Leak test methods must comply with
State, Local and National codes including the National Fuel Gas Code NFPA 54/ANSIZ233.1 (Latest Edition).
6. Always install furnace with a duct system that has an external static pressure within
the allowable range referenced in specifications.
7. Make sure supply air ducts are completely sealed to the furnace casing. Refer to
Section IV.

The following pages contain various warnings and cautions found throughout the
Thermo Pride Gas Fired High Efficiency 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.
: Negative

pressure inside the closet with closet door closed and the
furnace blower operating on high speed shall be no more negative than minus
0.05 inch water column.
: Do not obstruct any return air openings, including the return grille on
the furnace. To do so may cause the furnace to activate the high limit and shut
down.

All installations and services must be performed by qualified service personnel.

: 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 CMA/CMC furnace has been designed to be installed as a direct
vent system and must have its combustion air brought in from outside the
conditioned space. 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.
: All gas piping must be leak tested methods approved by State, Local
and National Codes including the National Fuel Gas Code NFPA 54/ANSI-Z233.1
(Latest Edition). 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.
: 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.

: The furnace and its individual gas shutoff 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" w.c. The furnace must be isolated from
the gas supply by closing its manual shut off valve at test pressures equal to or
greater than 1/2 PSIG or 14.0" w.c.

All installations and services must be performed by qualified service personnel.

: 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. Check with your gas supplier.
: TURN OFF THE ELECTRICAL POWER to the furnace before attempting
to change blower speed wiring.
: 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 in
accordance with State, Local and National Codes including the National Fuel Gas
Code NFPA 54/ANSI-Z233.1 (Latest Edition).
: It may be necessary to purge the air out of the gas line for initial startup 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.
: 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 above for 15 minutes or until
odor has dissipated.
: The CMA/CMC furnace models are of direct vent design and do 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.

: Label wires prior to disconnection when servicing controls. Wiring
errors can cause improper and dangerous operation.
: The

inducer motor mounting plate gasket and the collector box gasket
must be replaced if they show any sign of having been damaged.
: Power must be disconnected before servicing.

All installations and services must be performed by qualified service personnel.

II. FURNACE SPECIFICATIONS
MODEL

CMA3-50D36

CMA3-75D36

50,000
48,000

75,000
72,000

INPUT IN BTUH
OUTPUT IN BTUH
MAIN ORIFICE-NAT.
MAIN ORIFICE-LP
GAS SUPPLY PRESSURE
L.P. MINIMUM
NAT. MINIMUM
L.P. MAXIMUM
NAT. MAXIMUM
GAS MANIFOLD PRESSURE
L.P.
NAT.
INTAKE SIZE IN INCHES
VENT SIZE IN INCHES
NOMINAL TEMPERATURE RISE
SEASONAL EFFICIENCY (AFUE*)
*ANNUAL FUEL UTILIZATION
EFFICIENCY
DIMENSIONS
CABINET SIZE
SUPPLY AIR OUTLET

#42
#54
11” IN.W.C.
4.5”IN.W.C.
14” IN.W.C.
14” IN.W.C.
10.0” + .03 IN.W.C.
3.5” + .03 IN. W.C.
2”
2”
55°F

65°F
95%

WIDTH 18” DEPTH 25-3/4" HEIGHT 57"
WIDTH 12” DEPTH 12"

ELECTRICAL SUPPLY
FUSE OR HACR BREAKER
TOTAL CURRENT AMPS
NOMINAL ANTICIPATOR SETTING

115 VOLTS-- 60HZ --1/PH
15 AMPS
7.15 AMPS
0.8 MILLIAMPS

FILTER SIZE
APPROXIMATE SHIPPING WEIGHT

(1) 18” X 24” X 1”
175 LBS.

BLOWER DATA
BLOWER MODEL
MOTOR HORSEPOWER
MOTOR RPM
CFM @ .2 & .5 IN. W.C.

185 LBS.

12-9T DIRECT DRIVE
1/2 PSC
1065 (HIGH SPEED)
SPEED
LOW
MD-LOW
MD-HIGH
HIGH

.2”
805
1010
1196
1338

.5”
695
860
1038
1162

|
|
|
|
|

.2”
797
995
1210
1420

FOR BURNER COMBUSTION INFORMATION REFER TO INITIAL STARTUP.

.5”
668
869
1076
1259

All installations and services must be performed by qualified service personnel.

MODEL

CMC1-50D36

CMC1-75D36

50,000
48,000

75,000
72,000

#42
#54
11” IN.W.C.
4.5”IN.W.C.
14” IN.W.C.
14” IN.W.C.
10.0” + .03 IN.W.C.
3.5” + .03 IN. W.C.
2”
2”
55°F

WIDTH 18” DEPTH 25-3/4" HEIGHT 57"
WIDTH 12” DEPTH 12"

ELECTRICAL SUPPLY
FUSE OR HACR BREAKER
TOTAL CURRENT AMPS
NOMINAL ANTICIPATOR SETTING

115 VOLTS-- 60HZ --1/PH
15 AMPS
7.15 AMPS
0.8 MILLIAMPS

FILTER SIZE
APPROXIMATE SHIPPING WEIGHT

(1) 18” X 24” X 1”
195 LBS.

BLOWER DATA
BLOWER MODEL
MOTOR HORSEPOWER
MOTOR RPM
CFM @ .2 & .5 IN. W.C.

65°F
95%

205 LBS.

12-9T DIRECT DRIVE
1/2 PSC
1065 (HIGH SPEED)
SPEED
LOW
MD-LOW
MD-HIGH
HIGH

.2”
805
1010
1196
1338

.5”
695
860
1038
1162

|
|
|
|
|

.2”
797
995
1210
1420

FOR BURNER COMBUSTION INFORMATION REFER TO INITIAL STARTUP.

.5”
668
869
1076
1259

All installations and services must be performed by qualified service personnel.

MODEL

CMC1-50DV3

CMC1-75DV3

50,000
48,000

75,000
72,000

#42
#54
11” IN.W.C.
4.5”IN.W.C.
14” IN.W.C.
14” IN.W.C.
10.0” + .03 IN.W.C.
3.5” + .03 IN. W.C.
2”
2”
55°F

WIDTH 18” DEPTH 25-3/4" HEIGHT 57"
WIDTH 12” DEPTH 12"

ELECTRICAL SUPPLY
FUSE OR HACR BREAKER
TOTAL CURRENT AMPS
NOMINAL ANTICIPATOR SETTING
FILTER SIZE
APPROXIMATE SHIPPING WEIGHT

115 VOLTS-- 60HZ --1/PH
15 AMPS
7.15 AMPS
0.8 MILLIAMPS
(1) 18” X 24” X 1”
195 LBS.

BLOWER DATA
BLOWER MODEL
MOTOR HORSEPOWER
MOTOR RPM
CFM @ .2 & .5 IN. W.C.

65°F
95%

205 LBS.

12-9T DIRECT DRIVE
1/2 ECM
1075 (HIGH SPEED)
SPEED
LOW
MD-LOW
MED
MD-HIGH
HIGH

.2”
639
834
948
1145
1365

.5”
437
653
811
1026
1265

|
|
|
|
|

.2”
935
998
1113
1177
1272

FOR BURNER COMBUSTION INFORMATION REFER TO INITIAL STARTUP.

.5”
802
880
1007
1083
1177

All installations and services must be performed by qualified service personnel.

INSTALLATION PARTS PACKAGES

PARTS PKG#
DESCRIPTION
J-box cover
Wire nut
3" stainless steel hose clamp
2-3/8" radiator hose
CPVC adapter
LP conversion kit

PARTS PKG#
DESCRIPTION
J-box cover
Wire nut
3" stainless steel hose clamp
2-3/8" radiator hose
CPVC adapter
LP conversion kit
Gasket, drain knock-out
Grommet, vinyl 3/8"
Grommet, vinyl 7/8"
Screw, #8 x 1/2 Tek
Coil trim panel

CMA3-50D36N
S00S4248
PART #
QTY
350020
1
300132
2
300276
4
410017
2
320833
1
AOPS7741
1

CMA3-75D36N
S00S4249
PART #
QTY
350020
1
300132
2
300276
4
410017
2
320833
1
AOPS7742
1

CMC1-50D36N
S00S4190
QTY
PART #
1
350020
2
300132
4
300276
2
410017
1
320833
1
AOPS7741
1
330355
1
350040
1
350009
6
300208
1
619113

CMC1-75D36N
S00S4191
QTY
PART #
1
350020
2
300132
4
300276
2
410017
1
320833
1
AOPS7742
1
330355
1
350040
1
350009
6
300208
1
619113

CMC1-50DV3N
S00S4244
PART #
QTY
350020
1
300132
2
300276
4
410017
2
320833
1
AOPS7741
1
330355
1
350040
1
350009
1
300208
6
619113
1
390111
42"

CMC1-75DV3N
S00S4245
PART #
QTY
350020
1
300132
2
300276
4
410017
2
320833
1
AOPS7742
1
330355
1
350040
1
350009
1
300208
6
619113
1
390111
42"

All installations and services must be performed by qualified service personnel.

III. GENERAL INSTRUCTIONS AND CLEARANCES – READ BEFORE START OF
INSTALLATION
1. 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 the American Society of Heating,
Refrigeration and Air Conditioning Engineers, Inc. (ASHRAE).
2. This furnace is equipped with orifices sized for operation with natural gas. For
conversion to Propane Gas see instruction MG-815 in Gas Conversion Kit
AOPS7743.
3. 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 40°F to 70°F through the furnace after
installation. For the Energy Star Eco Tech models the temperature rises are 40°F to
70°F for the 50 series and 50°F to 80°F for the 75 series. (See rating label located
on separator 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.
4. 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.
5. The installer shall be familiar with and comply with all codes and regulations
applicable to the installation of these heating appliances and related equipment. In
lieu of local codes, the installation shall be in accordance with the current provisions
of one or more of the following standards.
a. Federal Manufactured Home Constructions & Safety Standard (H.U.D. Total
24, Part 280.)
b. American National Standard (ANSI-119.2/NFPA-501C) for all recreational
vehicle installations.
c. American National Standard (ANSI-Z223.1/NFPA-54) for all gas-fired
furnaces.

All installations and services must be performed by qualified service personnel.

d. American National Standard (ANSI-C1/NFPA-70 Electric Code for all
electrical field wiring.
e. These gas-fired units have been investigated under standards ANSI Z 21.47
CAN/CGA Z223-2001 Central Furnace test standards.
f. These gas-fired units have been listed by ETL “For installation as central
furnace special type for single story dwelling.”

: The area around the furnace must be kept free and clear of
combustible materials, especially papers and rags.
: This furnace is not to be used as a construction heater.
Listed below are definitions of “ COMBUSTIBLE MATERIAL” and “NONCOMBUSTIBLE MATERIAL.”
COMBUSTIBLE MATERIAL:
Material made of or surfaced with wood, compressed paper, plant fibers, plastics or
other material that will ignite.
NON-COMBUSTIBLE MATERIAL:
Material that will not ignite and burn. Such materials consist entirely of steel, iron, brick,
tile, concrete, slate, glass or a plaster combination thereof.
MODELS CMA3/CMC1
FRONT
BACK
SIDES
VENT CONNECTOR(PVC)
TOP
PLENUM SIDES
TOP AND SIDES OF DUCT
BOTTOM OF DUCT

CLOSET
6”
0”
0”
0”
0”
1”
1”
1”

ALCOVE
18”
0”
0”
0”
0”
1”
1”
1”

Table 1
This heating appliance must be installed with clearances not less than the minimums
shown above as well as ample clearance for easy access to the air filter, blower
assembly, burner assembly, controls, and vent connections.

All installations and services must be performed by qualified service personnel.

IV. GENERAL INSTALLATION
A. FURNACE LOCATION
1. For best performance, locate the furnace so that it is centralized with respect
to the duct system.
2. The furnace installation is only intended for free air return through the furnace
door louvers. DO NOT connect a ducted return air system directly to the furnace.
An improper return air installation may create a hazard and damage equipment,
as well as void all warranties.
3. Model CMA3 furnace may be installed on a combustible floor when utilizing
either the No. 70 counterflow floor base or CE113S / CE213T coil cabinet for
below the floor duct systems, or the cottage base for floor level air distribution.
See Figure 1A for description of Combustible Floor Base and Figure 1C for
Cottage Base.
4. Model CMC1 furnace is designed to be installed directly on a combustible
floor and is not required to be installed on a base.
This furnace is ETL listed for closet, alcove or free standing applications. All
applications must comply with the requirements of this manual.
Combustible Floor Base Model: 70-BASE
For CMA3 models only.

Figure 1A.

All installations and services must be performed by qualified service personnel.

Coil Cabinet Model: CE113S / CE213T
Note: Coil cabinet cannot be utilized as a cottage base.

CE113S

CE213T
Figure 1B.

Cottage Base Model: 01COT-BASE
For CMA3 models only.
NOTE: Serves as a plenum for single story applications with exposed supply air
systems.

Figure 1C.

All installations and services must be performed by qualified service personnel.

B. BASE INSTALLATION – CMA3 models only
1. Combustible Floor Base Model: 70 BASE (for CMA3 models only)
Use the base bottom panel as a template to mark floor opening locations (see
Figure 2). Cut a square opening in the floor for the supply air connector duct. Cut
the opening 1-inch larger than the square template opening. (duct requires 1-inch
clearance to combustible floor).

Figure 2.

Figure 3.
After cutting openings in the floor, place the bottom panel in position. Mark the
square opening location on the distribution duct at the connection point of the

All installations and services must be performed by qualified service personnel.

connector duct. Remove the bottom panel. Cut an opening in the distribution duct
slightly larger than the connector duct. (refer to Figure 2 for location of this cut.)
Cut the connector duct to length. Install the connector duct. Bend over each tab.
Insure an airtight seal by using high temperature sealant or tape on the joint.
Reinstall the bottom panel over the connector duct. Put the base top assembly in
place (see Figure-3).
Slit the corners of connector duct down to the top of the base assembly. If metal
projects more than 1-inch above the top of the base assembly, trim the flanges
down to 1-inch. While the top of distribution duct is being pulled up with one
hand, bend down each side of the connector duct tightly to the base assembly
with the other hand. This assures a tight connection between the base assembly
and the connector duct and that the distribution duct will be full size. Use high
temperature tape and/or high temperature silicone caulking on all joints and
seams to minimize air leakage. Secure the base assembly to the floor with two
screws in the front flange.
2. Cottage Base Model: 01COT BASE (for CMA3 models only)
The 01COT BASE cottage base (Figure 1C) is required for a freestanding
cottage base installation. The cottage base allows the two sides and rear to have
an 8” x 12” register installed. IMPORTANT: All joints and seams of supply
ducts must be sealed with a sealing method suitable to the application
conditions and temperatures (I.E. High temperature silicone and/or
aluminum tape). Refer to assembly and installation instructions included with
cottage base for additional information.
The model CMC does not require a base for installation. The integrated coil
cabinet serves as a base. The duct connection will be made to the bottom of the
furnace. A sheet metal cover plate may be installed to protect any exposed
combustible flooring.

All installations and services must be performed by qualified service personnel.

C. ALCOVE INSTALLATION
In this application, a minimum of 18 inches of clearance must be provided to the
front of the unit. See Figure 4.
Note – access to diagnostic view port.

CMA3 SERIES

CMC1 SERIES

Figure 4.

D. CLOSET INSTALLATION
1. The return air opening into the closet is to have a minimum free area of 250
sq. in. (see Figure 5).
2. The return air opening may be located in the top, center or (ideally) bottom of
the closet door or side wall.

All installations and services must be performed by qualified service personnel.

CMA3 SERIES

CMC1 SERIES

Figure 5.
Do not obstruct any return air openings, including the return
grille on the furnace. To do so may cause the furnace to activate the high
limit and shut down.
:

3. The cross-sectional area of the return system leading into the closet (when
located in the floor or ceiling) shall not be less than 250 square inches.
4. The total free area of openings in the floor or ceiling registers serving the
return duct system must be at least 350 square inches. At least one register must
be located where it is not likely to be covered by carpeting, boxes, furniture or
other objects.
5. Materials located in the return duct system must have a flame spread
classification of 200 or less.
6. Non-combustible pans having one inch upturned flanges are to be located
beneath openings in a floor return duct system.
7. Wiring materials located in the return duct system must conform to articles
300-22 of the National Electrical Code NFPA70 (Latest Edition).
8. Gas piping is not to be located in or through the return duct system.
18

All installations and services must be performed by qualified service personnel.

E. FUEL PIPING
Sizing and installation of fuel lines must be in accordance with Federal, State &
Local regulations. Including the National Fuel Gas Code NFPA 54/ANSI-Z233.1
(Latest Edition).
NOTE: These furnaces are designed to be gas piped through the left side or the
bottom. For service purposes, it is recommended that the gas union be located
inside the furnace when possible.
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.
:

A qualified installer or service person must perform all gas piping and testing.
Piping from the natural gas meter to the furnace shall be in accordance with
requirements of the local gas utility. Piping from the LP tank to the furnace must
follow the recommendations of the gas supplier.
A readily accessible manual shut off valve (certified for the applicable gas) with a
non-displaceable rotor member shall be installed within six feet of the gas
equipment it serves.
A union or flanged connection shall be provided directly up stream of the burner
to allow burner removal. Unions must be of a ground joint type or flange-jointed
type using a gasket resistant to the applicable gas. Pipe dope or sealant certified
to be resistant to the action of the applicable gases should be used on all
threaded joints.
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 pipe connections must be leak tested using methods
approved by State, Local and National Fuel Gas Code NFPA 54/ANSI-Z233.1
(Latest Edition). Any leaks must be repaired immediately after turning off
the gas supply. A final test for gas leakage must be made after purging the
gas line.
:

: DO NOT wet electronic components during the leak test.
Wetting electronic components may damage circuitry and cause a
hazardous situation. Dry moisture from all leads and terminals if wetting

All installations and services must be performed by qualified service personnel.

occurs. Wait at least 24 hours for the circuit to fully dry before energizing
the system.
: The furnace and its 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 inches w.c

F. GENERAL VENTING REQUIREMENTS
The CMA/CMC furnace venting system must be installed by a qualified service
person in accordance with local codes, the National Fuel Gas Code NFPA
54/ANSI-Z223.1 (Latest Edition) and these instructions.
The following items and local code requirements must be followed:
1. The vent/air intake terminations outlined by Thermo Products in this
manual must be used.
2. The entire vent/air intake system must be made of PVC Schedule 40 pipe
except for the concentric vent kit. NOTE: All CMA/CMC furnaces must be
installed with outside combustion air.
3. The flue vent pipe and combustion air pipe must be at least as large as the
exhaust vent/air intake pipe specified by Thermo Products. No reduction in
size is permissible. The CMA/CMC requires 2” Schedule 40 PVC pipe.
4. This furnace shall not be common vented with any other appliance
including those burning solid fuels.
5. The maximum permissible vent length of straight pipe and number of
elbows permitted for the exhaust vent and combustion air inlet is shown in
Table 2. The elbows shown are in addition to the length of straight pipe
permitted. When counting elbows, all elbows used in the exhaust vent or
combustion air intake must be counted. This includes elbows used inside the
furnace jacket and termination elbows.
Care should be taken to plan out the vent system to be as short as possible
(but not shorter than 8 ft.) and to contain as few elbows as possible to insure
the best possible operation of the furnace.

All installations and services must be performed by qualified service personnel.

MAXIMUM VENT LENGTH
VENT SIZE
FURNACE
MODEL

2 IN. PVC
EXHAUST
COMBUSTION AIR INTAKE
VENT
ELBOWS (NO.)
ELBOWS
(NO.)
CMA*/CMC*
30
8*
7**
*Note the drain elbow supplied with furnace count as 1 elbow.
**Note the two 45° elbows supplied with furnace count as 1 elbow.
VENT
LENGTH
(FT.)

Table 2
6. A hack saw may be used to cut the PVC pipe. It must be cut smoothly at
right angles with all burrs removed. All joints must use standard PVC
Schedule 40 elbows and couplings. Joints are not to be made by gluing,
except where noted, and butting together the cut or raw edges of the vent
pipe. (The joints inside the vestibule should be sealed with a silicone caulk to
allow for maintenance.) Notice: Do not use silicone caulk to seal the PVC
sleeve or coupling to the metal air intake collar on the burner box. The
screw securing the sleeve or coupling to the collar is sufficient.
7. Use the two radiator hose clamps to connect both the exhaust vent and
combustion air vent pipes to the venting system (included in the parts
package.) This will aid in the serviceability of the vent should it need to be
removed in the future. (Refer to figure 6).
8. Vent connections shall be checked for leakage with the furnace induced
draft blower running and with the vent termination blocked. A mild soap and
water solution may be used to check for leaks.
9. Vent pipe passing through an unheated space must be insulated with 1.0”
thick foil faced fiberglass insulation or its equivalent to prevent freezing of any
condensate within the pipe.
10. Minimum clearance from the PVC pipe to combustible material is zero
inches.
IMPORTANT: The CMA/CMC furnace models are vented through the roof.
For roof venting refer to Section IV, J, of this manual.

All installations and services must be performed by qualified service personnel.

G. CONNECTING THE EXHAUST VENT AND COMBUSTION AIR INTAKE
Figure 6. shows the typical exhaust vent and combustion air intake connection
for CMA/CMC furnace.

Figure 6.
Models CMA and CMC have a removable top front panel that will allow for
improved access to assist installation of the exhaust vent and combustion air
intake connection to the top of the furnace. Access is gained by removal of two
screws in the upper right and left of the furnace. The top front access panel is
then removed by pulling forward. Once the vent connections are made, the top
front access panel is replace. Be sure the access panel fits the around the two
grommets that secure the vent pipes and the rear tab locks below the top rear
panel. For Energy Star models, adhesive backed aluminum tape has been
provided to seal the access panel to the furnace top to make an air tight seal at

All installations and services must be performed by qualified service personnel.

the conclusion of the vent pipe installation. This will insure a leak free return air
compartment. Refer to Figure 6A.

Figure 6A.
NOTICE: The exhaust vent pipe must be supported every 4 feet. After making
sure the length of the piping is correct glue all connections in place.
: This CMA/CMC furnace has been designed to be installed as a
direct vent system and must have its combustion air brought in from
outside the conditioned space. 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.
NOTICE: The furnace model series CMA/CMC may be vented either
through the sidewall or the roof. For sidewall instructions, continue to the
following section. For roof venting, refer to Section IV J, of this manual.
NOTICE: The air intake pipe must be supported every 4 feet. After making sure
the length of the piping is correct, glue all connections in place except the
connection to the burner box.
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 1.0” foil faced
insulation or its equivalent.
If the vent piping is run through an unconditioned space, it must be insulated with
a 1.0” foil faced insulation or its equivalent.
: 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

All installations and services must be performed by qualified service personnel.

gas flame. Should acid compounds form in your furnace, it may reduce the
life of the furnace.

H. Direct Venting Through a Sidewall
1. Vent And Combustion Air Pipes
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
7, the maximum distance from the outer wall to the center of the elbow is 12
inches.

Figure 7: 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. Exhaust Vent Termination Elbow
The exhaust vent termination elbow shall be installed in accordance with
these instructions and any applicable local codes. Refer to Figures 7 and 8 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.

All installations and services must be performed by qualified service personnel.

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 24inches.
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.

Figure 8: 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 9 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
25

All installations and services must be performed by qualified service personnel.

•

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.

Figure 9: NFGC Minimum Clearances Between the Vent Terminal and Various
Building Features
26

All installations and services must be performed by qualified service personnel.

4. Vent Terminal Location Guidelines
: 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 wideopen 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.

I. 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), 2-3/8 inch
diameter holes in the outside wall for the outdoor terminal(s)

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.) 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
H., 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 10, making sure that the spacing between the inlet and
outlet complies with that noted in Figure 8.

All installations and services must be performed by qualified service personnel.

Figure 10: 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. 320219.

J. CONNECTING THE FURNACE TO ROOF VENT / AIR TERMINATIONS
The CMA/CMC is designed to be vented with either a concentric vent assembly
or twin 2” pvc stacks. The concentric vent (AOPS7483) can be vented through
the ceiling/roof either thru the existing roof jack or thru the 3” ceiling/roof flashing
plate.
Concentric vent utilizing existing roof jack as a chase.
Follow instructions included with concentric vent kit AOPS7483.
Concentric vent without roof jack as a chase.
Follow instructions included with concentric vent kit AOPS7483.
Dual 2” vent/air termination kit AOPS7484
1. Remove roof jack assembly.
2. Place a 2” (2-holes) ceiling/roof flashing plate to the ceiling centering it
over existing hole.
3. Place second flashing plate on roof over existing hole.
4. Plate must be sealed to roof to ensure a weather proof seal.
5. Secure plate to roof.
6. Drop pvc pipes thru holes in flashing plates.
7. Secure with hose clamps to flashing plate.
8. Seal with silicone type caulk.
28

All installations and services must be performed by qualified service personnel.

The furnace may be vented vertically through the roof. The outlet/inlet of the vent
and air intake terminations shall be a minimum of 12 inches above highest
anticipated snow level. The vent outlet must be installed a minimum of 12 in.
above the air intake inlet. The combustion air intake shall be installed upwind of
the vent outlet when exposed to prevailing winds. The exhaust vent and
combustion air intake can be a minimum of 3 in. and a max. of 24 in. apart (see
Figures 11 & 12). When installing dual 2” PVC pipes and the 2” flashing plates
(AOPS7484) on pitched roof, slope adapter may be used to simplify installation.

Figure 11.

Figure 12.
When the PVC vent and combustion air intake pipes pass through a ceiling, and
a fire stop is required. Refer to the following:

All installations and services must be performed by qualified service personnel.

CEILING: Frame out area around where PVC pipe is to penetrate ceiling. Cut a
2-3/8” diameter hole for 2” PVC in the ceiling and a corresponding hole in a
firestop to be made of a minimum of 18 gauge galvanized metal large enough to
cover the entire framed area. Cut PVC pipe so that it extends up past the fire
stop far enough to engage a PVC coupling that will rest on the fire stop and act
as a support. Seal between the pipe coupling and fire stop with high temperature
RTV silicone sealant (see Figure 13). Continue installing PVC pipe to exhaust
vent and combustion air intake termination as described previously.

Figure 13.

K. CONDENSATE DRAIN LINE AND TRAP ASSEMBLY
1. Figure 14 illustrates the typical drain
trap connection for a CMA/CMC furnace.
(Trap will be installed at factory.)
Connect condensate drain trap to
building drain system.
2. An optional condensate neutralizer kit
(P/n 320095) is available when gas
furnace condensate needs to be
neutralized (pH increased) prior to
discharge into drain system.
3. An optional mini condensate pump
(P/N 350224) is available. This pump
will fit into the vestibule of the furnace.
Instructions will be included with pump if
this option is utilized.
Figure 14.

All installations and services must be performed by qualified service personnel.

L. ELECTRICAL 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 (LATEST
EDITION).
1. Electrical Branch Supply Circuit
Route all electrical wiring to the left side of the furnace. The power supply
circuit to the furnace must be installed and grounded in accordance with the
provisions of the National Electrical Code, ANSI/NFPA-70-1999, or latest
edition, and all local codes having jurisdiction.
2. Connection Of Power Supply Wires
a. Remove the cover from junction box.
b. Insert 115 VAC wires through the strain relief bushing (or conduit
connection as applicable) on the left side of the furnace junction box.
c. Connect the “hot” wire to the black wire.
d. Connect the “neutral” wire to the white wire.
e. Connect the “ground” wire to the green wire.
f. Reinstall and secure the junction box cover with the original mounting
screws.
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 (L1) and the common leg (L2) 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 (Latest Edition)
when an external electrical source is utilized.

3. Connection Of Room Thermostat Wires
NOTE: Class 1 thermostat wire must be used inside the furnace burner
compartment.
a. Insert 24 VAC wires through the plastic grommet on the left side of the
furnace casing.
b. Connect the thermostat wires to the W/R 50A65-143 control (refer to the
wiring diagram).
c. Connect the thermostat wires to the room thermostat.

All installations and services must be performed by qualified service personnel.

IMPORTANT: The room thermostat should be installed 4 to 5 feet above
the floor on an interior wall which is relatively free from direct sources of
heat (sunlight or supply airflow) or exposure to cold (drafts from open
windows and doors). The nominal anticipator setting is 0.8 amperes, for
the CMA/CMC (refer to the thermostat literature for additional information).
Four-conductor thermostat wire is recommended for 24 VAC, low-voltage,
control circuit wiring. However, only 2 wires are required for the furnace (a
heating application only).

Electrical Wire
Diameter
(AWG)
24
22
20
18

Maximum Recommended
Thermostat Wire Length
(Feet)
55
90
140
225

Once the furnace is installed, check the thermostat anticipator for proper
nominal setting.
1. Connect a multimeter, capable of reading milliamps (mA), in series
with the low voltage wires to the thermostat.
2. Increase the thermostat setting, or create a “call for heat”.
3. Read the value of the thermostat current, in milliamps.
4. Adjust the heat anticipator of the thermostat to the value read by the
multimeter.
If the heat anticipator is set too high, the furnace may delay activation of a
heating cycle for too long. If the heat anticipator is set too low, the furnace
may cycle too frequently. Either condition may not provide optimal
comfort to the homeowner.

All installations and services must be performed by qualified service personnel.

4. BLOWER MOTOR SPEED WIRING

Figure 15.
BLOWER DELAY SETTINGS
To delay fan
turn-on by:
15 sec.
30 sec.
*45 sec.
60 sec,

#1
Off
Off
On
On

Set Switch
#2
Off
On
Off
On

To delay fan
Set Switch
turn-off by:
#3
#4
60 sec.
On
On
90 sec.
Off
On
*120 sec.
On
Off
180 sec.
Off
Off
*Factory Settings For Optimal Performance

All installations and services must be performed by qualified service personnel.

CMA3-50D36
ALTERATIONS REQ’D FOR A/C @ DESIGN EXTERNAL STATIC PRESSURE

COOLING UNIT

HTG Speed

Recommended CLG Speed

LOW
LOW
LOW

MED-LOW
MED-HIGH
HIGH

24,000
30,000
36,000

Speed Tap \
Static
Pressure
Low
ML
MH
High

Speed Tap
\ Static
Pressure
Low
ML
MH
High

Speed Tap \
Static
Pressure
Low
ML
MH
High

Furnace Airflow (CFM) vs. External Static pressure (in. WC.)

0.1
836
1044
1250
1339

0.2
805
1010
1196
1338

0.3
773
972
1146
1283

0.4
743
914
1101
1233

0.5
695
860
1038
1162

0.6
620
826
977
1086

0.7
566
752
902
1008

Temperature Rise vs. External Static Pressure (in. WC.)

0.1
53
42
35
31

0.2
55
44
37
33

0.3
57
45
38
34

0.4
59
48
40
36

0.5
63
51
42
38

0.6
71
53
45
41

0.7
78
59
49
44

Blower Motor Current Draw (Amps) vs. External Static pressure (in. WC.)
0.1

0.2

0.3

0.4

0.5

0.6

0.7

3.3
4.0
4.6
5.3

3.2
3.8
4.4
5.1

3.1
3.6
4.2
5.0

3.0
3.5
4.1
4.9

2.9
3.4
4.0
4.7

2.7
3.2
3.8
4.6

2.6
3.1
3.6
4.4

Blower Motor Watts vs. External Static pressure (in. WC.)

0.1
315
400
485
573

0.2
311
390
467
555

0.3
304
376
452
544

0.4
300
363
441
530

= Recommended operation range

0.5
292
351
427
513

0.6
281
342
412
493

0.7
275
330
394
477

All installations and services must be performed by qualified service personnel.

CMA3-75D36
ALTERATIONS REQ’D FOR A/C @ DESIGN EXTERNAL STATIC PRESSURE
COOLING UNIT

HTG Speed

Recommended CLG Speed

MED-LOW
MED-LOW
MED-LOW

MED-LOW
MED-HIGH
HIGH

24,000
30,000
36,000

Speed Tap \
Static
Pressure
Low
ML
MH
High

Furnace Airflow (CFM) vs. External Static pressure (in. WC.)
0.1
817
1019
1257
1470

0.2
797
995
1210
1420

0.3
773
959
1174
1366

0.4
730
918
1125
1312

0.5
668
869
1076
1259

0.6
620
821
1024
1196

0.7
555
760
959
1127

Temperature Rise vs. External Static Pressure (in. WC.)
0.1
81
65
52
45

0.2
83
66
55
46

0.3
85
69
56
48

0.4
90
72
59
50

0.5
90
76
61
52

0.6
106
80
64
55

0.7
119
87
69
59

Blower Motor Current Draw (Amps) vs. External Static pressure (in. WC.)
0.1

0.2

0.3

0.4

0.5

0.6

0.7

3.1
3.9
4.8
5.7

3.0
3.8
4.6
5.5

2.9
3.6
4.4
5.4

2.8
3.5
4.2
5.2

2.7
3.3
4.1
5.1

2.6
3.2
4.0
5.0

2.5
3.1
3.8
4.8

Blower Motor Watts vs. External Static pressure (in. WC.)
0.1
312
400
513
624

0.2
303
390
490
605

0.3
298
381
478
591

0.4
291
366
462
573

= Recommended operation range

0.5
280
354
447
556

0.6
273
342
432
542

0.7
264
330
413
522

All installations and services must be performed by qualified service personnel.

CMC1-50D36
ALTERATIONS REQ’D FOR A/C @ DESIGN EXTERNAL STATIC PRESSURE

COOLING UNIT

HTG Speed

Recommended CLG Speed

LOW
LOW
LOW

MED-LOW
MED-HIGH
HIGH

24,000
30,000
36,000

Speed Tap \
Static
Pressure
Low
ML
MH
High

Speed Tap
\ Static
Pressure
Low
ML
MH
High

Speed Tap \
Static
Pressure
Low
ML
MH
High

Furnace Airflow (CFM) vs. External Static pressure (in. WC.)

0.1
836
1044
1250
1339

0.2
805
1010
1196
1338

0.3
773
972
1146
1283

0.4
743
914
1101
1233

0.5
695
860
1038
1162

0.6
620
826
977
1086

0.7
566
752
902
1008

Temperature Rise vs. External Static Pressure (in. WC.)

0.1
53
42
35
31

0.2
55
44
37
33

0.3
57
45
38
34

0.4
59
48
40
36

0.5
63
51
42
38

0.6
71
53
45
41

0.7
78
59
49
44

Blower Motor Current Draw (Amps) vs. External Static pressure (in. WC.)
0.1

0.2

0.3

0.4

0.5

0.6

0.7

3.3
4.0
4.6
5.3

3.2
3.8
4.4
5.1

3.1
3.6
4.2
5.0

3.0
3.5
4.1
4.9

2.9
3.4
4.0
4.7

2.7
3.2
3.8
4.6

2.6
3.1
3.6
4.4

Blower Motor Watts vs. External Static pressure (in. WC.)

0.1
315
400
485
573

0.2
311
390
467
555

0.3
304
376
452
544

0.4
300
363
441
530

= Recommended operation range

0.5
292
351
427
513

0.6
281
342
412
493

0.7
275
330
394
477

All installations and services must be performed by qualified service personnel.

CMC1-75D36
ALTERATIONS REQ’D FOR A/C @ DESIGN EXTERNAL STATIC PRESSURE
COOLING UNIT

HTG Speed

Recommended CLG Speed

MED-LOW
MED-LOW
MED-LOW

MED-LOW
MED-HIGH
HIGH

24,000
30,000
36,000

Speed Tap \
Static
Pressure
Low
ML
MH
High

Furnace Airflow (CFM) vs. External Static pressure (in. WC.)
0.1
817
1019
1257
1470

0.2
797
995
1210
1420

0.3
773
959
1174
1366

0.4
730
918
1125
1312

0.5
668
869
1076
1259

0.6
620
821
1024
1196

0.7
555
760
959
1127

Temperature Rise vs. External Static Pressure (in. WC.)
0.1
81
65
52
45

0.2
83
66
55
46

0.3
85
69
56
48

0.4
90
72
59
50

0.5
90
76
61
52

0.6
106
80
64
55

0.7
119
87
69
59

Blower Motor Current Draw (Amps) vs. External Static pressure (in. WC.)
0.1

0.2

0.3

0.4

0.5

0.6

0.7

3.1
3.9
4.8
5.7

3.0
3.8
4.6
5.5

2.9
3.6
4.4
5.4

2.8
3.5
4.2
5.2

2.7
3.3
4.1
5.1

2.6
3.2
4.0
5.0

2.5
3.1
3.8
4.8

Blower Motor Watts vs. External Static pressure (in. WC.)
0.1
312
400
513
624

0.2
303
390
490
605

0.3
298
381
478
591

0.4
291
366
462
573

= Recommended operation range

0.5
280
354
447
556

0.6
273
342
432
542

0.7
264
330
413
522

All installations and services must be performed by qualified service personnel.

CMC1-50DV3
ALTERATIONS REQ’D FOR A/C @ DESIGN EXTERNAL STATIC PRESSURE

COOLING UNIT

HTG Speed

Recommended CLG Speed

LOW
LOW
LOW

MED-LOW
MED-HIGH
HIGH

24,000
30,000
36,000

Speed Tap \
Static
Pressure
Low
ML
MED
MH
High

Speed Tap
\ Static
Pressure
Low
ML
MED
MH
High

Furnace Airflow (CFM) vs. External Static pressure (in. WC.)

0.1
700
876
990
1174
1398

0.2
639
834
948
1145
1365

0.3
567
781
907
1107
1326

0.4
497
725
857
1066
1299

0.5
437
653
811
1026
1265

0.6
387
602
756
987
1252

0.7
332
556
700
942
1190

Temperature Rise vs. External Static Pressure (in. WC.)

0.1
63
50
44
37
31

0.2
69
53
46
38
32

0.3
78
56
48
40
33

0.4
88
61
51
41
34

0.5
101
67
54
43
35

0.6
114
73
58
45
35

0.7
132
79
63
47
37

Blower Motor Current Draw (Amps) vs. External Static pressure (in. WC.)
0.1

0.2

0.3

0.4

0.5

0.6

0.7

1.1
1.7
2.2
3.4
5.2

1.2
1.8
2.3
3.4
5.2

1.2
1.8
2.4
3.5
5.3

1.2
1.9
2.5
3.6
5.3

1.3
1.9
2.5
3.6
5.4

1.4
2.0
2.5
3.7
5.5

Blower Motor Watts vs. External Static pressure (in. WC.)

Speed Tap \
Static
Pressure

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Low

123

127

133

137

141

145

148

MED

168

173

178

183

188

192

197

266

272

277

284

290

296

301

High

438

442

445

450

455

461

468

= Recommended operation range

All installations and services must be performed by qualified service personnel.

CMC1-75DV3
ALTERATIONS REQ’D FOR A/C @ DESIGN EXTERNAL STATIC PRESSURE

Speed Tap \
Static
Pressure
Low
ML
MED
MH
High

COOLING UNIT

HTG Speed

Recommended CLG Speed

24,000
30,000
36,000

MED-LOW
MED-LOW
MED-LOW

MED-LOW
MED-HIGH
HIGH

Furnace Airflow (CFM) vs. External Static pressure (in. WC.)
0.1
970
1043
1148
1212
1300

0.2
935
998
1113
1177
1272

0.3
898
968
1080
1142
1229

0.4
846
928
1051
1119
1211

0.5
802
880
1007
1083
1177

0.6
765
830
968
1047
1144

0.7
710
785
929
1023
1117

Temperature Rise vs. External Static Pressure (in. WC.)
0.1
75
70
64
60
56

0.2
78
73
66
62
57

0.3
81
76
68
64
59

0.4
86
79
70
65
60

0.5
91
83
73
67
62

0.6
96
88
76
70
64

0.7
103
93
79
71
65

Blower Motor Current Draw (Amps) vs. External Static pressure (in. WC.)
0.1

0.2

0.3

0.4

0.5

0.6

0.7

2.4
2.8
3.6
4.2
4.8

2.5
2.9
3.7
4.2
4.9

2.5
3.0
3.7
4.3
5.0

2.6
3.0
3.8
4.3
5.0

2.6
3.1
3.8
4.4
5.1

2.7
3.1
3.9
4.5
5.2

2.7
3.2
3.9
4.5
5.2

Blower Motor Watts vs. External Static pressure (in. WC.)
0.1
187
225
290
341
408

0.2
190
229
295
347
414

0.3
195
233
299
353
423

0.4
200
238
303
356
428

0.5
204
244
310
364
435

= Recommended operation range

0.6
206
248
315
369
441

0.7
211
252
320
371
445

All installations and services must be performed by qualified service personnel.

: TURN OFF THE ELECTRICAL POWER to the furnace
before attempting to change blower speed wiring.
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. (Refer to figure 15)
Refer to section II for blower speed and air flow performance for A/C
installation.
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 35 C wire. 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.

All installations and services must be performed by qualified service personnel.

V. STARTING THE UNIT
A. SEQUENCE OF OPERATIONS

AT ANY TIME THE
GAS VALVE IS
NOT ENERGIZED

CONTINUOUS SAFE OPERATION CHECK
IF FLAME SIMULATION CONDITION
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
ADEQUATE DIFFERENTIAL PRESSURE,
CONTACTS CLOSE

POWER IS APPLIED TO
THE SILICON NITRIDE
IGNITOR. IGNITOR
WARM-UP IS 20 SECONDS.

START
TRIAL
FOR
IGNITION

POWER INTERRUPTION
SYSTEM SHUTS OFF,
RESTARTS WHEN POWER
IS RESTORED.

AFTER IGNITOR WARM-UP,
THE GAS VALVE IS
ENERGIZED TO OPEN

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.

All installations and services must be performed by qualified service personnel.

MAIN
BURNER
OPERATION

CALL
FOR
HEAT
SATISFIED

AFTER DELAY-TO-FAN-ON
PERIOD ENDS, CIRCULATING
AIR FAN IS ENERGIZED AT
HEATING SPEED. THE (OPTIONAL)
ELECTRONIC AIR CLEANER
AND HUMIDIFIER ARE
ENERGIZED.

WHEN THERMOSTAT IS
SATISFIED, CONTACTS
OPEN AND THE GAS
VALVE IS DE-ENERGIZED.
AFTER PROOF OF FLAME
LOSS, INDUCER STARTS 5 SECOND
POST SURGE AND (OPTIONAL)
HUMIDIFIER ARE
DE-ENERGIZED. THE DELAYTO-FAN-OFF PERIOD
BEGINS (120 SECONDS)

IF IGNITION ATTEMPT IS
UNSUCCESSFUL, ONE MORE
RETRY WILL BE MADE
BEFORE THE CONTROL BOARD
GOES INTO SYSTEM LOCKOUT.

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-TOFAN-OFF PERIOD ENDS,
THE CIRCULATING AIR
FAN AND (OPTIONAL)
ELECTRONIC AIR CLEANER
ARE DE-ENERGIZED.
END
OF CYCLE

THE RETRY SEQUENCE
PROVIDES A 60 SECOND
WAIT BEFORE IGNITION
RETRY. RETRY IS
ATTEMPTED WITH AN
ADDITIONAL 10 SECONDS
OF IGNITOR WARM-UP
TIME.

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.

All installations and services must be performed by qualified service personnel.

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
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 in accordance with State, Local and National Codes including
the National Fuel Gas Code NFPA 54/ANSI-Z233.1 (Latest Edition).
: 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.
: 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 as noted above for 15 minutes or until odor
has dissipated.

All installations and services must be performed by qualified service personnel.

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 75,000 BTU at sea level must be reduced to a firing rate of
60,000 (75,000 x .80 = 60,000) 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 or Thermo Products 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:
1. 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.
2. 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 dial will state the cubic feet of flow for one
revolution usually one, two or five.
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 = 73,505 BTU Input
100.40 Seconds
Check the model number of the furnace, the input rate, the type of gas,
and the manifold pressure on the rating label located in the burner
vestibule. If using the above example, the furnace is a CMA2-75N model
and the input rate is 73,505 BTU/hr. The input rate would be acceptable
because it was within + 2% of the listed input of 75,000.
3. Make sure that the gas supply pressure to the furnace is within the
allowable range of 5.5" to 14" WC pressure on natural gas and 11.0" to
14.0" WC 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. NPT manifold pressure tap.

All installations and services must be performed by qualified service personnel.

GAS PRESSURE CHART FOR CMA*/CMC* MODEL FURNACES
SUPPLY PRESSURE

MANIFOLD PRESSURE

NAT

MAX 14” WC
MIN 4.5” WC

3.5 + .3” WC

PROPANE

MAX 14” WC
MIN 11” WC

10.0” + .3” WC

TABLE 3
This gas furnace is equipped with a fixed orifice sized for the manifold
pressure shown on the rating label. The input can only be increased, or
decreased, by adjusting the manifold pressure. Remove the 1/8" threaded
pipe plug located on the gas manifold.
Use a U tube manometer or recently calibrated pressure gage to measure
the pressure. To adjust the pressure, remove the screw cap from the
regulator on 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 0.3" WC. A 0.3" WC 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 rating label if a gas meter is not available for
natural gas or the unit is installed on an unmetered propane gas supply.
Shut off the gas supply to the furnace. Remove the pressure gage and reinstall 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 may assist in sizing the proper orifice.
Thermo Products 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 fuel 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 16).
NOTE: It is not unusual to have orangish flames visible in the tube for LP gas.
45

All installations and services must be performed by qualified service personnel.

Figure 16.

: The CMA/CMC furnace models are direct vent design and do
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. SETTING TEMPERATURE RISE
All CMA/CMC Models are designed and wired at the factory for a heating blower
speed that should result in an approximate temperature rise of 60°F. The blower
motors are wired on med-low speed for heating mode. The temperature rise
through the furnace may vary depending on the duct system, elevation, heating
value, etc. for each installation. A lower temperature rise will result in a higher
efficiency. Temperature rise = supply air temperature - return air temperature.
After 10 to 15 minutes of continuous operation, the temperature rise through the
furnace must fall within a range of 40°F to 70°F. If the outlet or supply duct
temperature is too high, you should check to make sure that your return air filter
is clean, your return air openings are free from obstruction, your outlet registers
are properly adjusted and clear and your supply and return air ducts are open.
The circulating air blower is not moving enough air if the supply air temperature is
still too high. Before proceeding further, turn off the power supply to the furnace
and remove the front door of the unit.
The speed of the blower must be increased by changing the speed tap from the
motor (see figure 15). This is accomplished by locating the control panel attached
to the blower housing and switching blower lead connected to the “Heat” terminal
on the White-Rodgers 50A65-143 control, with one of the higher speed blower
leads attached to a terminal marked “Park”. Be sure to attach any unused blower
leads to a terminal marked “Park”. Replace the blower door and turn on the
power supply.

All installations and services must be performed by qualified service personnel.

F. 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 Fuel Piping Section of this
Furnace 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. IMPORTANT: Remove flue outlet
blockage when done.
4. Block the PVC pipe inlet gradually with a flat piece of metal until pressure
switch functions shutting off the main burners. IMPORTANT: Remove 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.

All installations and services must be performed by qualified service personnel.

VI. 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 the instructions must
be kept along with instructions for any accessories in the plastic pouch.
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 this
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 in this 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 component.
8. Should the furnace not operate after installation – note diagnostic code
through view port prior to removing door.
VII. DEALER MAINTENANCE
The following maintenance procedures should be performed at the beginning
of each heating season by a qualified heating contractor. Correct any
deficiencies at once.
: Personal injury or property damage could result from repair or
service of this furnace by anyone other than a qualified heating contractor.
: To avoid injury from moving parts, shut off
furnace before removing blower compartment door.

the power to the

: Label wires prior to disconnection when servicing controls. Wiring
errors can cause improper and dangerous operation.

All installations and services must be performed by qualified service personnel.

A. ELECTRICAL:
1. Check diagnostic code through view port prior to removing access door.
2. Check all wiring for loose connections and any signs of damage or unusual
wear.
3. Check for correct voltage at the furnace when operating.
4. Check amp-draw on blower motor and inducer motor to assure they are not
exceeding name plate amp rating.
5. Check for correct operation and proper settings (if manually adjustable) of all
controls.
Shut off gas and disconnect power before continuing.

B. GENERAL INSPECTION
1. VENT PIPE COMBUSTION AIR INTAKE
a. Remove the vent and check the vent for signs of carbon build-up and for
signs of blockage.
b. The entire length of vent and combustion air inlet pipe and their
terminations should be inspected for restrictions, loose or loosely sealed
joints, carbon build-up. Also inspect the outside vent and combustion air
terminals and ensure that they are clear and unobstructed.
2. CONDENSATE LINE/TRAP ASSEMBLY
The condensate line must be inspected to make sure it is not blocked. All of the
lines should be flushed with water to remove any build-up of sediment.
3. BURNERS
If it appears that material is accumulating in the burner box, the burner box cover
can be removed and the box and burners can be vacuumed. (NOTE: The igniter
& flame sensor must be removed before removing the assembly.) If necessary,
the burner assembly can be removed by taking out the two screws/one on each
bracket at the bottom of the box. Assembly must be pulled & tilted away from the
burner compartment in order to remove from box. If necessary, the individual
tubes can be cleaned out by using compressed air.Care must be taken not to
damage the igniter.
4. INDUCER BLOWER ASSEMBLY
Inspect the pressure switch and drain tubing connections and inspect the
blower/assembly for warpage, deterioration and carbon or other build-up. If
necessary, clean the accessible portions of the housing and blower with a damp
cloth. Vacuum to remove any lint or dust from the motor assembly.

All installations and services must be performed by qualified service personnel.

5. GASKETS/SEALING MATERIALS
Inspect all visible gaskets for signs of degradation or liquid seepage, especially
any seals which were removed as part of the inspection. Replace any suspect
gaskets.
C. HEAT EXCHANGER
Inspect for corrosion, pitting, warpage, deterioration, carbon build-up and loose
gaskets in the flue pipe, burner box and accessible areas of the heat exchanger.
1. CLEANING THE COIL AIR SIDE
a. Remove the blower from the blower compartment. In order to remove the
blower, it will first be necessary to disconnect the furnace from the outside
power supply and disconnect the blower wire harness from the furnace at
the blower pan quick connect.
b. Clean the coil with a vacuum cleaner by going through the blower pan
opening being careful not to bend or damage any of the fins.
c. Once all components are cleaned, they must be re-installed to their factory
produced state. Any seals or joints in the flue system which have been
removed or loosened must be reconnected and sealed if necessary. Do
this in accordance with the installation instructions.
The inducer motor mounting plate gasket and the collector box
gasket must be replaced.
:

D. HOUSE AIR BLOWER
Check and clean the blower wheel, housing and compartment with a vacuum.
Check the motor name plate and follow the motor manufacturers instructions for
lubrication, if required.
IMPORTANT: Some motors are permanently lubricated and should not be
oiled. See motor name plate for specific instructions.

E. RETURN AIR FILTER
The Return Air Filter(s): Provided with this unit is a permanent type filter. This
filter(s) should be inspected and when dirty, cleaned or replaced, if necessary to
assure proper furnace operation. Follow the cleaning, removal and replacement
procedure below.

All installations and services must be performed by qualified service personnel.

FILTER MAINTENANCE PROCEDURE
The filter is located inside front door of the CMA/CMC. Remove filter retaining rod
and remove dirty filter. Clean the filter by vacuuming, rinsing with tap water,
hosing or dipping in an ordinary detergent solution. After cleaning, replace the
completely dry filter and retain with retaining rod. If the filter has a mesh, the
mesh side of the filter must be towards the furnace.
FILTER REPLACEMENT
Should the filter require replacement, replace with like size and type filter as
originally supplied with furnace.
IMPORTANT: Remind homeowner of importance of monthly filter inspections
during the heating season to ensure efficient and trouble-free operation of their
furnace.
VIII. 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.
Note – check diagnostic code through view port prior to removing access door.
DIAGNOSTIC FEATURES
The 50A65 control used on this furnace continuously monitors its operation and the
operation of the system. If a failure occurs, the LED light on the control will flash a
code. If the failure is internal to the control, the light will stay on continuously.
In this case, the entire control should be replaced, as the control is not fieldrepairable.
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

system locked
pressure switch stuck closed

All installations and services must be performed by qualified service personnel.

3 flashes, then pause
4 flashes, then pause
6 flashes, then pause
7 flashes, then pause
8 flashes, then pause

pressure switch stuck open
open high limit switch
115 volt AC power reversed
low flame sense signal
check ignitor or improper grounding

Continuous flashing
Flame has been sensed when
(no pause)
no flame should be present
(no call for heat)
The LED will also flash once at power-up.
: Power must be disconnected before servicing.

All installations and services must be performed by qualified service personnel.

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.
NOTE: CHECK DIAGNOSTIC CODE THROUGH VIEW PORT PRIOR TO REMOVING ACCESS DOOR.

TURN THERMOSTAT TO CALL FOR HEAT
DOES THERMOSTAT MAKE CONTACT?

Yes

IS ROOM TEMPERATURE
BELOW THERMOSTAT
SETTING?

IS ROOM
TEMPERATURE
ABOVE 90 DEGREES F?

No
TURN T'STAT
SETTING ABOVE
ROOM TEMP.

Yes

COOL THE THERMOSTAT
IS THE TRANSFORMER
SUPPLYING 24 VOLTS
TO THE THERMOSTAT?

No
ARE WIRES CONNECTED
PROPERLY?

Yes

CORRECT WIRE
CONNECTIONS

Yes

REPLACE
THERMOSTAT

IS INTERNAL DAMAGE
PRESENT ON THE
TRANSFORMER?

CHECK INPUT
POWER, DOOR
INTERLOCK,
SERVICE SWITCH
AND FUSES.

Yes
REPLACE TRANSFORMER

Yes

IS THE INDUCER
BLOWER OPERATING?

IS THERE 24 VOLTS
ACROSS "TH" & "TR"
AT THE INTEGRATED
CONTROL MODEL?

Yes
Yes

CHECK FOR
CONTINUITY
& PROPER
CONNECTIONS

All installations and services must be performed by qualified service personnel.

Yes

IS THERE LINE VOLTAGE
ACROSS INDUCER POWER
TERMINALS "IND" & "IND N"
AT THE INTEGRATED CONTROL?
Yes

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.

CHECK WIRING TO INDUCER
AND IF OK, REPLACE
INDUCER ASSEMBLY.

DOES THE HOT
SURFACE
IGNITOR ENERGIZE
AND GLOW?

IS THERE VOLTAGE PRESENT
AT THE HOT SURFACE
IGNITOR TERMINALS
"IGN" & "IGN N" AT THE
INTEGRATED CONTROL?

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

AFTER HOT SURFACE
IGNITOR WARM-UP,
DOES GAS VALVE OPEN?

Yes

CHECK WIRING TO
HOT SURFACE IGNITOR
AND IF OK, REPLACE
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?

Yes

CHECK WIRING TO GAS
VALVE AND IF OK,
REPLACE GAS VALVE.

SAME AS ABOVE.

All installations and services must be performed by qualified service personnel.

Yes

AFTER GAS VALVE
OPENS, DO THE
BURNERS IGNITE?

CHECK FOR PROPER
MANIFOLD PRESSURE.

ADJUST TO 3.5" FOR NATURAL GAS
OR 10.0" WC FOR LP GAS

Yes
Yes
IS IGNITOR
POSITIONED CORRECTLY?

REPOSITION TO
CORRECT LOCATION.

DO BURNERS STAY
LIT PAST PROOF
OF FLAME CHECK?

Yes

DOES THE INTEGRATED CONTROL
ENERGIZE THE
CIRCULATING AIR BLOWER
AFTER THE 45 SECOND
TIME DELAY.

CHECK ACROSS THE
CIRCULATING AIR
BLOWER TERMINALS
"CIR N" & "HEAT"
FOR PROPER VOLTAGE.

REPLACE THE
INTEGRATED CONTROL.

Yes

DOES THE CIRCULATING
AIR FAN COME ON
WHEN ENERGIZED?

DOES BLOWER
SPIN FREELY?

Yes

CONFIRM IF
EITHER BLOWER WHEEL
IS RUBBING AGAINST
HOUSING OR MOTOR
SHAFT IS SPINNING
FREELY AND REPAIR
OR REPLACE AS NECESSARY.

Yes
IS CAPACITOR
WORKING PROPERLY
No
REPLACE CAPACITOR

Yes
REPLACE MOTOR

All installations and services must be performed by qualified service personnel.

Yes

DOES SYSTEM RUN UNTIL
THERMOSTAT IS SATISFIED?

IS LED LIGHT
ON INTEGRATED
CONTROL FLASHING?

CHECK ALL
WIRING FOR
LOOSE CONNECTIONS.

Yes
Yes

DOES BURNER SHUT OFF
WHEN THERMOSTAT IS
SATISFIED?

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

All installations and services must be performed by qualified service personnel.

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)
CHECK COMPLETE SYSTEM OUT.

THE LED WILL ALSO FLASH ONCE AT POWER-UP.
LED LIGHT STAYS ON CONTINUOUSLY,
COMPLETE FAILURE - REPLACE
INTEGRATED CONTROL.

TROUBLESHOOTING COMPLETE.

All installations and services must be performed by qualified service personnel.

APPENDIX – A REPLACEMENT PARTS

All installations and services must be performed by qualified service personnel.

APPENDIX – B WIRING DIAGRAMS

All installations and services must be performed by qualified service personnel.

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Thermo Products Pride Furnace Cma3 50D36N Users Manual

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