Resco GB3AAV Instructions and recipes

NOTE: Read the entire instruction manual before starting the installation.
Index Page
SAFETY CONSIDERATIONS.....................................................................................................................................................................................2
Clearances From Combustible Materials.................................................................................................................................................................2
INTRODUCTION......................................................................................................................................................................................................2-3
Dimensional Drawing...............................................................................................................................................................................................3
LOCATION................................................................................................................................................................................................................3-4
General ..................................................................................................................................................................................................................3-4
Location Relative to Cooling Equipment.............................................................................................................................................................3-4
Hazardous Locations................................................................................................................................................................................................4
AIR FOR COMBUSTION AND VENTILATION ..................................................................................................................................................4-6
Unconfined Space.....................................................................................................................................................................................................4
Confined Space .....................................................................................................................................................................................................4-6
SUPPLY-AIR PLENUM INSTALLATION (DOWNFLOW).....................................................................................................................................6
Installation On a Concrete Slab...............................................................................................................................................................................6
Installation On a Combustible Floor .......................................................................................................................................................................6
HORIZONTAL ATTIC INSTALLATION ..................................................................................................................................................................7
Construct a Working Platform.................................................................................................................................................................................7
Install Furnace..........................................................................................................................................................................................................7
HORIZONTAL CRAWLSPACE INSTALLATION................................................................................................................................................7-8
FILTER ARRANGEMENT.......................................................................................................................................................................................8-9
GAS PIPING............................................................................................................................................................................................................9-10
ELECTRICAL CONNECTIONS ..........................................................................................................................................................................11-12
115-v Wiring ..........................................................................................................................................................................................................11
24-v Wiring ............................................................................................................................................................................................................11
Accessories........................................................................................................................................................................................................11-12
VENTING....................................................................................................................................................................................................................13
START-UP, ADJUSTMENT, AND SAFETY CHECK ......................................................................................................................................13-20
General....................................................................................................................................................................................................................13
Sequence Of Operation.....................................................................................................................................................................................13-15
Heating Mode.........................................................................................................................................................................................................13
Cooling Mode.........................................................................................................................................................................................................13
Continuous Blower Mode.................................................................................................................................................................................13-15
Heat Pump Mode....................................................................................................................................................................................................15
Start-up Procedures ................................................................................................................................................................................................15
Adjustments.......................................................................................................................................................................................................15-19
Check Safety Controls......................................................................................................................................................................................19-20
Checklist .................................................................................................................................................................................................................20
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CANADIAN GAS ASSOCIATION
APPROVED
R
Installation, Start-Up, and Operating Instructions
GB3AAV
Downflow/Horizontal Gas Fired
Induced-Combustion Furnaces
Sizes 050 thru 135 Series C
Form: IM-GB3A-04 Cancels: IM-GB3A-03 Printed in U.S.A. 4-94 Catalog No. 92-33GB-3A5

SAFETY CONSIDERATIONS
Installing and servicing heating equipment can be hazardous due to gas and electrical components. Only trained and qualified personnel should
install, repair, or service heating equipment.
Untrained personnel can perform basic maintenance functions such as cleaning and replacing air filters. All other operations must be performed
by trained service personnel. When working on heating equipment, observe precautions in the literature, on tags, and on labels attached to or
shipped with the unit and other safety precautions that may apply.
Follow all safety codes. In the United States, follow all safety codes including the National Fuel Gas Code (NFGC) NFPA No. 54-1992/ANSI
Z223.1-1992. In Canada, refer to the current edition of the National Standard of Canada CAN/CGA-B149.1- and .2-M91 Natural Gas and Propane
Installation Codes (NSCNGPIC). Wear safety glasses and work gloves. Have fire extinguisher available during start-up and adjustment procedures
and service calls.
Recognize safety information. This is the safety-alert symbol . When you see this symbol on the unit and in instructions or manuals, be alert
to the potential for personal injury.
Understand the signal word DANGER, WARNING, or CAUTION. These words are used with the safety-alert symbol. DANGER identifies the
most serious hazards which will result in severe personal injury or death. WARNING signifies a hazard that could result in personal injury or death.
CAUTION is used to identify unsafe practices which would result in minor personal injury or product and property damage. NOTE is used to
highlight suggestions that will result in enhanced installation, reliability, or operation.
These instructions cover minimum requirements and conform to existing national standards and safety codes. In some instances, these instructions
exceed certain local codes and ordinances, especially those that may not have kept up with changing residential construction practices. We require
these instructions as a minimum for a safe installation.
INTRODUCTION
The model GB3AAV Series C Furnaces are available in sizes 50,000 through 135,000 Btuh input capacities.
The design of the downflow/horizontal gas-fired furnace is A.G.A./C.G.A. certified for natural and propane gas and for installation on
noncombustible flooring. The furnace may be installed on combustible flooring when installed with the accessory downflow subbase. This furnace
is for installation in alcoves, attics, crawlspaces, basements, closets, or utility rooms. The design of this furnace line is not A.G.A./C.G.A. certified
for installation in mobile homes, recreation vehicles, or outdoors.
Before installing the furnace, refer to the current edition of the NFGC. Canadian installations must be installed in accordance NSCNGPIC and all
authorities having jurisdiction. For further information, the NFGC is available from National Fire Protection Association Inc. Batterymarch Park,
Quincy, MA 02269, American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209, or from Literature Distribution.
Table 1—Clearances From Combustible Materials (In.)
UNIT SIZE 050 AND 070 095-135
DOWNFLOW (In Alcove or Closet)
Sides Single-Wall Vent 1 0
Type B-1 Double-Wall Vent 0 0
Back 0 0
Top 1 1
Front Single-Wall Vent 6† 6†
Type B-1 Double-Wall Vent 3† 3†
Vent Single-Wall Vent 6 6
Type B-1 Double-Wall Vent 1 1
HORIZONTAL (Attic, Alcove, or Crawlspace)
Sides * 1 0
Back 0 0
Top Single-Wall Vent 1 1
Type B-1 Double-Wall Vent 1 1
Front‡ Single-Wall Vent 6† 6†
Type B-1 Double-Wall Vent 3† 3†
Vent Single-Wall Vent 6 6
Type B-1 Double-Wall Vent 1 1
HORIZONTAL (In Closet)
Sides * 1 1
Back 0 0
Top Single-Wall Vent 2 2
Type B-1 Double-Wall Vent 2 2
Front Single-Wall Vent 6 6
Type B-1 Double-Wall Vent 3 3
Vent Single-Wall Vent 6 6
Type B-1 Double-Wall Vent 1 1
* Indicates supply or return sides when furnace is in the horizontal position.
† Clearance shown is for outlet end. The inlet end must maintain 6-in. minimum clearance from the vent to combustible materials when using single-wall vent.
‡ Minimum 18-in. front clearance required for alcove.
NOTES:
1. Provide 30-in. front clearance for servicing. An open door in front of the furnace can meet this requirement.
2. A minimum clearance of 3 in. must be provided in front of the furnace for combustion air and proper operation.
3. Line contact is permitted as shown in Fig. 7.
—2—

Table 2—Dimensions (In.)
UNIT SIZE A D E VENT CONN SHIP. WT
024050 14-3/16 12-9/16 12-11/16 4 124
036050 14-3/16 12-9/16 12-11/16 4 127
024070 14-3/16 12-9/16 12-11/16 4 141
036070 14-3/16 12-9/16 12-11/16 4 145
036095 17-1/2 15-7/8 16 4 154
048095 17-1/2 15-7/8 16 4 154
048115 17-1/2 15-7/8 16 4 171
060115 21 19-3/8 19-1/2 4 181
060135 24-1/2 22-7/8 23 5 192
CAUTION: Application of this furnace should be indoors with special attention given to vent sizing and material, gas
input rate, air temperature rise, and unit sizing. Improper installation or misapplication of the furnace can require excessive
servicing or cause premature component failure.
Installation must conform to the regulations of the serving gas supplier and the local building, heating, and plumbing codes in effect in the area
in which the installation is made, or in the absence of local codes with the requirements of the NFGC.
This furnace is designed for a minimum continuous return-air temperature of 60°F db or intermittent operation down to 55°F db such as when used
with a night setback thermostat. Return-air temperature must not exceed a maximum of 85°F db.
WARNING: Improper installation, adjustment, alteration, service, maintenance, or use can cause carbon monoxide
poisoning, explosion, fire, electrical shock, or other conditions which may cause personal injury, loss of life, or property
damage. Consult a qualified installer, service agency, local gas supplier, or your distributor or branch for information or
assistance. The qualified installer or agency must use only factory-authorized and listed kits or accessories when modifying
this product. Failure to follow this warning could result in electrical shock, fire, personal injury, or death.
For accessory installation details, refer to the applicable installation literature.
NOTE: Remove all shipping brackets and materials before operating the furnace.
PROCEDURE 1—LOCATION
A. General
CAUTION: Do not install furnace in a corrosive or contaminated atmosphere. Make sure all combustion and
circulating air requirements are followed, in addition to all local codes and ordinances.
Do not use this furnace during construction when adhesives, sealers, and/or new carpets are being installed. If the furnace
is required during construction, use clean outside air for combustion and ventilation. Compounds of chlorine and fluorine
when burned with combustion air form acids which cause corrosion of the heat exchangers and metal vent system. Some
of these compounds are found in paneling and dry wall adhesives, paints, thinners, masonry cleaning materials, and many
other solvents commonly used in the construction process.
Fig. 1—Dimensional Drawing A88324
—3—

This furnace must be installed so the electrical components are protected from water.
Locate the furnace as close to the chimney/vent and as near the center of the air distribution system as possible. The furnace should be installed
as level as possible.
When a furnace is installed so that the supply ducts carry air to areas outside the space containing the furnace, the return air must also be handled
by a duct(s) sealed to the furnace casing and terminating outside the space containing the furnace.
Provide ample space for servicing and cleaning. Always comply with the minimum fire protection clearances shown on the unit rating plate. This
furnace shall not be installed directly on carpeting, tile, or any combustible material other than wood flooring. The furnace may be installed on
combustible flooring when installed with the accessory downflow subbase, which is available from your distributor or branch when required.
B. Location Relative to Cooling Equipment
The cooling coil must be installed parallel with or on the downstream side of the furnace to avoid condensation in the heat exchangers. When
installed parallel with a furnace, dampers or other means used to control the flow of air must prevent chilled air from entering the unit. If the
dampers are manually operated, they must be equipped with means to prevent operation of either unit unless the damper is in the full-heat or
full-cool position.
C. Hazardous Locations
When the furnace is installed in a residential garage, it must be installed so that the burners and ignition source are located at least 18 in. above
the floor. The furnace should be protected from physical damage by vehicles.
When a furnace is installed in public garages, airplane hangars, or other buildings having hazardous atmospheres, the unit must be installed in
accordance with the recommended good practice requirements of the National Fire Protection Association, Inc.
PROCEDURE 2—AIR FOR COMBUSTION AND VENTILATION
Provisions for adequate combustion and ventilation air must be provided in accordance with Section 5.3 of the NFGC, Air for Combustion and
Ventilation, or applicable provisions of the local building codes.
Canadian installations must be installed in accordance with NSCNGPIC and all authorities having jurisdiction.
CAUTION: Air for combustion must not be contaminated by halogen compounds, which include fluoride, chloride,
bromide, and iodide. These elements are found in aerosol sprays, detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products.
CAUTION: The operation of exhaust fans, kitchen ventilation fans, clothes dryers, or fireplaces could create a
NEGATIVE PRESSURE CONDITION at the furnace. Make-up air MUST be provided for the ventilation devices, in addition to
that required by the furnace.
All fuel-burning equipment must be supplied with air for combustion of the fuel. Sufficient air MUST be provided to ensure there will not be a
negative pressure in the equipment room or space. In addition, a positive seal MUST be made between the furnace cabinet and the return-air duct
to avoid pulling air from the burner area and draft safeguard opening.
The requirements for combustion and ventilation air depend upon whether the furnace is located in an unconfined or confined space.
A. Unconfined Space
An unconfined space must have at least 50 cu ft for each 1000 Btuh of input for all the appliances (such as furnaces, clothes dryer, water heaters,
etc.) in the space.
For Example:
GB3AAV FURNACE
INPUT BTUH
MINIMUM SQ FT
WITH
7-1/2 FT CEILING
46,000 307
69,000 460
92,000 613
115,000 767
135,000 920
If the unconfined space is constructed unusually tight, air for combustion and ventilation MUST come from either the outdoors or spaces freely
communicating with the outdoors. Combustion and ventilation openings must be sized the same as for a confined space. A minimum opening with
a total of at least 1 sq in. per 5000 Btuh of total input rating for all equipment must be provided. Return air must not be taken from the room unless
an equal or greater amount of air is supplied to the room.
B. Confined Space
A confined space is defined as one whose volume is less than 50 cu ft per 1000 Btuh of the total input ratings of all appliances installed in that
space. A confined space MUST have 2 permanent openings, 1 within 12 in. of the ceiling, and the other within 12 in. of the floor. (See Fig. 2.)
NOTE: In determining the free area of an opening, the blocking effect of the louvers, grilles, and screens must be considered. If the free area of
a louver or grille design is unknown, assume that wood louvers have a 20 percent free area and metal louvers or grilles have a 60 percent free
area. Screens, when used, must not be smaller than 1/4-in. mesh. Louvers and grilles must be constructed so they cannot be closed.
The size of the openings depends upon whether the air comes from inside or outside the structure.
—4—

1. All air from inside the structure:
a. Each opening MUST have at least 1 sq in. of free area per 1000 Btuh of the total input for all equipment within the confined space, but
not less than 100 sq in. per opening. (See Fig. 2.)
For Example:
GB3AAV FURNACE
INPUT BTUH FREE AREA PER OPENING (SQ IN.)
46,000 100
69,000 100
92,000 100
115,000 115
135,000 138
b. If the building is constructed unusually tight, a permanent opening directly communicating with the outdoors should be provided. This
opening should have a minimum free area of 1 sq in. per 5000 Btuh of total input rating for all equipment in the enclosure.
c. If the furnace is installed on a raised platform to provide a return-air plenum, and return air is taken directly from the hallway or space
adjacent to the furnace, all air for combustion must come from outdoors. (See Fig. 3.)
2. All air from outside the structure:
a. If combustion air is taken from outdoors through vertical ducts, the openings and ducts MUST have at least 1 sq in. of free area per 4000
Btuh of the total input for all equipment within the confined space.
For Example:
GB3AAV FURNACE
INPUT BTUH FREE AREA PER OPENING (SQ IN.) ROUND PIPE (IN. DIA)
46,000 11.5 4
69,000 17.3 5
92,000 23.0 6
115,000 28.8 7
135,000 34.5 7
b. If combustion air is taken from the outdoors through horizontal ducts, the openings and ducts MUST have at least 1 sq in. of free area
per 2000 Btuh of the total input for all equipment within the confined space.
Fig. 2—Air for Combustion and Ventilation
(Inside Air)
A93387
RETURN
AIR
6″MIN
(FRONT) †
SUPPLY AIR
VENT THROUGH ROOF
(CATEGORY I)
1 SQ IN.
PER 1000
BTUH*IN DOOR
OR WALL
12″MAX
1 SQ IN.
PER 1000
BTUH*IN DOOR
OR WALL
12″MAX
INTERIOR
HEATED
SPACE
* Minimum opening size is 100 square in. with
minimum dimensions of 3-In.
† Minimum of 3-In. when type B-1 vent is used.
UNCONFINED
SPACE
—5—

For Example:
GB3AAV FURNACE
INPUT BTUH FREE AREA PER OPENING (SQ IN.) ROUND PIPE (IN. DIA)
46,000 23.0 6
69,000 34.3 7
92,000 46.0 8
115,000 57.6 9
135,000 69.0 10
c. When ducts are used, they must be of the same cross-sectional area as the free area of the openings to which they connect. The minimum
dimension of rectangular ducts must not be less than 3 in. (See Fig. 3.)
PROCEDURE 3—SUPPLY-AIR PLENUM INSTALLATION (DOWNFLOW)
A. Installation On a Concrete Slab
1. Construct hole in floor per dimensions in Fig. 4 and Table 3.
2. Install plenum and furnace as shown in Fig. 5.
Table 3—Opening Dimensions (In.)
FURNACE CASING
WIDTH AB
Heat-Only Heat/Cool*
14-3/16 13-1/8 19-5/8 19-7/16
17-1/2 16-7/16 19-5/8 19-7/16
21 19-7/8 19-5/8 19-7/16
24-1/2 23-7/16 19-5/8 19-7/16
* These dimensions apply when a model CB or CD Evaporator Coil casing is to be installed.
B. Installation On a Combustible Floor
1. Cut and frame hole in floor per dimensions in Installation Instructions packaged with downflow subbase.
2. When completed, downflow subbase, plenum, and furnace (or coil casing when used) should be installed as shown in Fig. 6.
Fig. 3—Air for Combustion and Ventilation
(Outside Air)
A93388
DUCTS TO
OUTDOORS 1 SQ IN.
PER 4000
BTUH*
RETURN
AIR VENT
THROUGH
ROOF
(CATEGORY I)
D
B
A
C
E
1 SQ IN.
PER 4000
BTUH
DUCT
TO
OUTDOORS
SUPPLY AIR
1 SQ IN.
PER 2000
BTUH*
DUCTS
TO
OUTSIDE
12″MAX 12″MAX
CONFINED
SPACE
12″
MAX
12″
MAX
1 SQ IN.
PER 4000
BTUH*
OUTDOORS
1 SQ IN.
PER 4000
BTUH*
1 SQ IN.
PER 2000
BTUH*
12″MAX
Use any of the following
combinations of openings:
A & B C & D D & E F & G
NOTE:
*Minimum dimensions of 3-In.
F
G
—6—

PROCEDURE 4—HORIZONTAL ATTIC INSTALLATION
WARNING: Do not install the furnace on its back; safety control operation will be adversely affected. Never connect
return-air ducts to the sides or back of the furnace. Failure to follow this warning could result in fire, personal injury, or death.
The furnace can be installed horizontally on either the left-hand (LH) or right-hand (RH) side. A typical attic installation is shown in Fig. 7.
A. Construct a Working Platform
Construct working platform on location where all required furnace clearances are met. (See Table 1 and Fig. 7.)
B. Install Furnace
1. Position furnace in desired location.
2. Connect gas supply pipe. See Fig. 7 for typical piping entry.
3. Install field-supplied filter retainers as indicated in Fig. 8 and Table 4 before connecting return-air duct to furnace.
4. Connect supply- and return-air ducts.
5. Install 24- X 24-in. sheet metal shield on platform in front of louvered control panel as shown in Fig. 7.
PROCEDURE 5—HORIZONTAL CRAWLSPACE INSTALLATION
The furnace can be installed horizontally with either the LH or RH side up. In a crawlspace, the furnace can either be hung from the floor joist
or installed on suitable blocks or pad. The furnace can be suspended from each corner by hanger bolts (4 each 3/8-in. all-thread rod) cut to desired
length, 1- X 3/8-in. flat washer, 3/8-in. lockwasher, and 3/8-in. nut. Dimples are provided for hole locations. (See Fig. 1.)
Since horizontal crawlspace installation is very similar to the attic installation, refer to Step IV. The installation of a sheet metal shield in front
of the louvered control panel is covered in Step IV. For a crawlspace installation, this same sheet metal shield must be installed above the louvered
control panel. Extend the sheet metal shield over the furnace top far enough to cover the gas pipe entry hole.
Fig. 4—Floor Opening for Concrete Slab A73382
HOLE IN
FLOOR
A
B
Fig. 5—Furnace on a Concrete Slab (Non-Garage Installation) A73383
FURNACE
PLENUM
—7—

PROCEDURE 6—FILTER ARRANGEMENT
WARNING: Never operate unit without a filter or with filter access door removed. Failure to follow this warning could
result in fire, personal injury, or death.
The 2 factory-supplied filters are shipped in the blower compartment. After the return-air duct has been connected to the furnace, install the filters
in a V-formation inside the return-air plenum. See Fig. 8 and Table 4 for horizontal applications. Horizontal filter retainers must be field supplied.
See Fig. 9 for downflow applications.
Fig. 6—Furnace, Plenum, and Subbase Installed on a Combustible Floor A78651
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
FURNACE
(OR COIL CASING
WHEN USED)
Fig. 7—Typical Attic Installation A82178
30-IN. MIN
WORK AREA
6
″
MIN
FLUE VENT
GAS
ENTRY
24 ″
24 ″
SHEET
METAL
SEDIMENT TRAP
LINE CONTACT ONLY PERMISSIBLE BETWEEN
LINES FORMED BY INTERSECTIONS OF
THE TOP AND TWO SIDES OF THE FURNACE
JACKET AND BUILDING JOISTS,
STUDS, OR FRAMING.
—8—

Table 4—Filter Retainer (In.)
FURNACE
CASING WIDTH FILTER SIZE AND QUANTITY D
14-3/16 (2) 14 X 20 X 1 14-3/8
17-1/2 (2) 14 X 20 X 1 13-3/8
21 (2) 16 X 20 X 1 11-5/8
24-1/2 (2) 16 X 20 X 1 10-1/4
PROCEDURE 7—GAS PIPING
Gas piping must be installed in accordance with national and local codes. Refer to the current edition of the NFGC.
Canadian installations must be installed in accordance with NSCNGPIC and all authorities having jurisdiction.
The gas supply line should be a separate line directly from the meter to the furnace, if possible. Refer to Table 5 for recommended gas pipe sizing.
Risers should be used to connect to the furnace and to the meter.
Fig. 8—Horizontal Filter Arrangement A82173








FIELD-SUPPLIED
FILTER RETAINERS
AIRFLOW
D
12″
4″
Fig. 9—Downflow Filter Arrangement A88486
RETURN-AIR
PLENUM









AIRFLOW
ACCESS DOOR
INSTALLATION
POSITION
OF FILTERS
—9—

Table 5—Maximum Capacity of Pipe *
NOMINAL
IRON PIPE
SIZE (IN.)
INTERNAL
DIAMETER (IN.) LENGTH OF PIPE (FT)
10 20 30 40 50
1/2 0.622 175 120 97 82 73
3/4 0.824 360 250 200 170 151
11.049 680 465 375 320 285
1-1/4 1.380 1400 950 770 660 580
1-1/2 1.610 2100 1460 1180 990 900
Ref: Table 10-2 NFPA 54/ANSI Z223.1-1992.
* Cubic ft of gas per hr for gas pressures of 0.5 psig (14-in. wc) or less, and a pressure drop of 0.5-in. wc (based on a 0.60 specific gravity gas).
CAUTION: If a flexible connector is required or allowed by the authority having jurisdiction, black iron pipe shall be
installed at the gas valve and extend a minimum of 2 in. outside the furnace casing.
WARNING: Use the proper length of pipes to avoid stress on the gas control manifold. Failure to follow this warning
could result in a gas leak, causing fire, explosion, personal injury, or death.
CAUTION: Connect the gas pipe to the furnace using a backup wrench to avoid damaging gas controls.
WARNING: Never purge a line into a combustion chamber. Never use matches, candles, flame, or other sources of
ignition to check for gas leakage. Use a soap-and-water solution to check for gas leaks. Failure to follow this warning could
result in fire, explosion, personal injury, or death.
Joint compounds (pipe dope) should be applied sparingly and only to the male threads of the joints. This pipe dope must be resistant to the action
of propane gas.
Install an accessible manual shut-off valve upstream of the furnace gas controls and within 72 in. of the furnace. A 1/8-in. NPT plugged tapping,
accessible for test gage connection, must be installed immediately upstream of the gas supply connection to the furnace and downstream of the
manual shut-off valve. Place a ground joint union between the gas control manifold and the manual shut-off.
Install a sediment trap in the riser leading to the furnace. The trap can be installed by connecting a tee to the riser leading from the furnace. Connect
a capped nipple into the lower end of the tee. The capped nipple should extend below the level of the gas controls. (See Fig. 10.)
Piping should be pressure tested in accordance with local and national plumbing and gas codes before the furnace has been attached. If the pressure
exceeds 0.5 psig (14-in. wc), the gas supply pipe must be disconnected from the furnace and capped before the pressure test. If the test pressure
is equal to or less than 0.5 psig (14-in. wc), close the manual shut-off valve located on the gas valve before the test. It is recommended that the
ground joint union be loosened before pressure testing.
After all connections have been made, purge the lines and check for gas leakage with regulated gas supply pressure.
Fig. 10—Typical Gas Pipe Arrangement A89414
GAS
SUPPLY
MANUAL
SHUTOFF
VALVE
SEDIMENT
TRAP
UNION
—10—
→

PROCEDURE 8—ELECTRICAL CONNECTIONS
A. 115-v Wiring
Refer to the unit rating plate or Table 6 for equipment electrical requirements. The control system requires an earth ground for proper operation.
CAUTION: Do not connect aluminum wire between disconnect switch and furnace. Use only copper wire.
Make all electrical connections in accordance with the current edition of the National Electrical Code (NEC) ANSI/NFPA 70-1993, and any local
codes or ordinances that might apply. For Canadian installations, all electrical connections must be made in accordance with Canadian Electrical
Code CSA C22.1, or authorities having jurisdiction.
NOTE: Proper polarity must be maintained for 115-v wiring. If polarity is incorrect, control center fault code indicator light will flash rapidly
and furnace will not operate.
WARNING: The cabinet MUST have an uninterrupted or unbroken ground according to NEC ANSI/NFPA 70-1990 and
Canadian Electrical Code CSA C22.1 or local codes to minimize personal injury if an electrical fault should occur. This may
consist of electrical wire or conduit approved for electrical ground when installed in accordance with existing electrical
codes. Do not use gas piping as an electrical ground. Failure to follow this warning could result in electrical shock, fire, or
death.
B. 24-v Wiring
Make field 24-v connections at the 24-v terminal strip. (See Fig. 11.) Connect terminal Y as shown in Fig. 13 for proper operation in cooling mode.
Use AWG No. 18 color-coded wire only.
The 24-v circuit contains an automotive-type, 3-amp fuse located on the main control board. Any direct shorts during installation, service, or
maintenance could cause this fuse to blow. If fuse replacement is required, use ONLY a 3-amp fuse of identical size.
C. Accessories
1. Electronic air cleaner (EAC)
Two spring clamp terminals (for 12 gage maximum, solid or stranded wire), marked EAC-1 and EAC-2, are provided for EAC connection.
(See Fig. 11.) These terminals are energized with 115v (1.5-amp maximum) during blower motor operation. To connect EAC power leads
to furnace control center, strip approximately 1/8 in. of insulation from wire. Open terminal by depressing switch arm with a screwdriver
or finger, and insert wire as shown in Fig. 12.
Fig. 11—Control Board A93052
G
R
Y
W
3-AMP FUSE
Com
24V
HUMIDIFIER TERMINAL
(24-VAC 0.5 AMP MAX)
LED OPERATION &
DIAGNOSTIC LIGHT
HARNESS CONNECTOR
24V TRANSFORMER SEC-2
SPARE 1
SPARE 2
EAC 1 (BLACK)
EAC-ELECTRONIC AIR CLEANER
TERMINALS (115-VAC 1 AMP MAX)
EAC 2 (WHITE)
115-VAC (L2) NEUTRAL
CONNECTION
24V THERMOSTAT
TERMINALS
BLOWER SPEED
SELECTION TERMINALS
INDUCER MOTOR
CONNECTOR
115-VAC (L1)
POWER
SUPPLY
HOT SURFACE
IGNITOR
CONNECTOR
HEAT
COOL
BLOWER OFF DELAY
ADJUSTMENT SWITCH
SEC-1
TEST/TWIN
HUM
—11—
→
→
→

2. Humidifier (HUM)
Screw terminals (HUM and C) are provided for 24-v humidifier connection. The terminals are energized with 24v (0.5-amp maximum) after
inducer motor prepurge period.
NOTE: A field-supplied, 115-v controlled relay connected to EAC terminals may be added if humidifier operation is desired during blower
operation.
Fig. 12—EAC Terminals on Control Board A93053
Fig. 13—Heating and Cooling Application Wiring Diagram A78461
115-VOLT FIELD-
SUPPLIED
FUSED
DISCONNECT
AUXILIARY
J-BOX
CONTROL
BOX
24-VOLT
TERMINAL
BLOCK
TWO-WIRE
HEATING-
ONLY
FOUR
WIRE
FIELD-SUPPLIED
FUSED DISCONNECT
CONDENSING
UNIT
TWO
WIRE
FURNACE
R
G
C
W R G Y
GND
GND
FIELD 24-VOLT WIRING
FIELD 115-, 208/230-, 460-VOLT WIRING
FACTORY 24-VOLT WIRING
FACTORY 115-VOLT WIRING
NOTE:
208/230- OR
460-VOLT
THREE
PHASE
208/230-
VOLT
SINGLE
PHASE
WHT
BLK
WHT
BLK
If any of the original wire,
as supplied, must be replaced, use
same type or equivalent wire.
NOTE: Connect Y-terminal as
shown for proper
operation.
W
Y
GND
THERMOSTAT
TERMINALS
Table 6—Electrical Data
UNIT SIZE VOLTS— HERTZ—
PHASE
OPERATING VOLTAGE RANGE MAXIMUM
UNIT AMPS MINIMUM WIRE GAGE MAXIMUM WIRE LENGTH FT‡
MAXIMUM
FUSE OR HACR-
TYPE CKT BKR
AMPS†
Maximum* Minimum*
024050 115—60—1 127 104 6.6 14 42 15
036050 115—60—1 127 104 8.1 14 34 15
024070 115—60—1 127 104 6.7 14 42 15
036070 115—60—1 127 104 8.4 14 33 15
036095 115—60—1 127 104 9.2 14 30 15
048095 115—60—1 127 104 10.2 14 28 15
048115 115—60—1 127 104 10.1 14 28 15
060115 115—60—1 127 104 13.3 12 33 20
060135 115—60—1 127 104 14.3 12 31 20
* Permissible limits of the voltage range at which the unit will operate satisfactorily.
† Time-delay fuse is recommended.
‡ Length shown is as measured 1 way along wire path between unit and service panel for maximum 2 percent voltage drop.
—12—
→

PROCEDURE 9—VENTING
Refer to the enclosed Installation Instructions, GAMA Venting Tables for Category I Furnaces and RESCO Tables for Category I Fan-Assisted
Furnaces. The horizontal portion of the venting system shall maintain a minimum of 1/4-in. upward slope per linear ft and it shall be rigidly
supported every 5 ft or less with hangers or straps to ensure that there will be no movement after installation.
PROCEDURE 10—START-UP, ADJUSTMENT, AND SAFETY CHECK
A. General
NOTE: Proper polarity must be maintained for 115-v wiring. If polarity is incorrect, control center fault indicator light will flash rapidly and
furnace will not operate.
The furnace must have a 115-v power supply properly connected and grounded. Proper polarity must be maintained for correct operation.
Thermostat wire connections at R,W,C, and Y must be made at the 24-v terminal block on the control board. The gas service pressure must not
exceed 0.5 psig (14-in. wc), but must be no less than 0.16 psig (4.5-in. wc).
Before operating the furnace, check each manual reset switch for continuity. If necessary, press the button to reset the switch.
The blower compartment door must be in place to complete the 115-v circuit to the furnace.
CAUTION: This furnace is equipped with 2 manual reset limit switches in the gas control area. The switches will open
and shut off power to the gas valve if a flame rollout or an overheating condition occurs in the gas control area. DO NOT
bypass the switches. Correct inadequate combustion air supply problem and reset the switches.
B. Sequence of Operation
CAUTION: Furnace control must be grounded for proper operation or control will lockout. Control is grounded
through green wire routed to gas valve and burner bracket screw.
Using the schematic diagram shown in Fig. 14, follow the sequence of operation through the different modes. Read and follow the wiring diagram
very carefully.
NOTE: If there is a power interruption and any thermostat call, the control will initiate a 90-sec blower only before starting another cycle.
1. Heating mode
When the thermostat "calls for heat," R-W circuit closes. The furnace control performs a self-check, verifies the pressure switch contacts
are open, and starts the inducer motor.
a. Prepurge period—As the inducer motor comes up to speed, the pressure switch contacts close to begin a 15-sec prepurge period.
b. Ignitor warm-up—At the end of the prepurge period, the ignitor is energized for a 17-sec ignitor warm-up period.
c. Ignition sequence—When the ignitor warm-up period is completed, the gas valve opens, permitting gas flow to the burners where it is
ignited. After 5 sec, the ignitor is de-energized and a 2-sec flame-sensing period begins.
d. HUM terminal is energized with the gas valve. See Accessories in Electrical Connections section.
e. Flame-sensing—When burner flame is sensed, the control begins the blower on delay period and continues holding the gas valve open.
If burner flame is not sensed, the control closes the gas valve and repeats the ignition cycle.
NOTE: Ignition sequence will repeat 3 additional times before a lockout occurs. Lockout automatically resets after 3 hrs, or can be manually reset
by turning 115v off (not at thermostat) for 3 sec minimum, then on again.
f. Blower on delay—Forty sec after burner flame is proven, the blower motor is energized on heating speed. Simultaneously, the humidifier
and electronic air cleaner terminals (HUM and C for humidifier, EAC-1 and EAC-2 for electronic air cleaner) are energized. Jumper is
on pin 6 and pin 9, blower on delay period is 60 sec.
g. Blower off delay—When the thermostat is satisfied, the circuit between R and W is broken, de-energizing the gas valve and stopping
gas flow to the burners. The blower motor, and EAC remain energized 90, 135, 180, or 225 sec (depending on the blower off time
selection). The furnace is factory set for a 135-sec blower off delay period.
h. Post-purge—The inducer motor remains energized 5 sec after the burners are extinguished. If jumper is on pin 6 and pin 9, the post-purge
period is 15 sec.
2. Cooling mode
When the thermostat "calls for cooling," R-G and R-Y circuits close. The R-Y circuit starts the outdoor condensing unit and combined R-Y
and R-G circuits start the furnace blower motor on cooling speed. The EAC-1 terminal is energized with 115v whenever the blower is
operating on cooling speed.
When the thermostat is satisfied, R-G and R-Y circuits are broken. Furnace blower and EAC continue operating on cooling speed for an
additional 90 sec.
3. Continuous blower mode
NOTE: EAC-1 terminal is energized with 115v whenever blower is operating.
When the R-G circuit is made, the blower motor operates on heating speed. During a call for heat, the blower stops, allowing the furnace
heat exchangers to heat up more quickly, then restarts at the end of the 40-sec blower on delay period. If jumper is on pin 6 and pin 9, the
blower on delay period is 60 sec.
—13—
→
→

→Fig. 14—Unit Wiring Diagram A94074
AUXILIARY LIMIT SWITCH, OVERTEMP.- MANUAL RESET, SPST-(N.C.) BLOWER MOTOR RELAY, SPST-(N.O.) BLOWER MOTOR CAPACITOR MICROPROCESSOR AND CIRCUITRY DRAFT SAFEGUARD SWITCH ELECTRONIC AIR CLEANER CONNECTION (115 VAC 1.5 AMP MAX.) ELECTRONIC AIR CLEANER CONNECTION (COMMON) FLAME ROLLOUT SW.-MANUAL RESET, SPST-(N.C.) FLAME PROVING ELECTRODE FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE (FIELD INSTALLED & SUPPLIED) GAS VALVE-REDUNDANT OPERATORS GAS VALVE RELAY, DPST-(N.O.) BLOWER MOTOR SPEED CHANGE RELAY, DPST-(N.O.) HOT SURFACE IGNITER (115 VAC) HOT SURFACE IGNITER RELAY, SPST-(N.O.) 24VAC HUMIDIFIER CONNECTION (.5 AMP. MAX.) INDUCED DRAFT MOTOR INDUCED DRAFT RELAY, DPST-(N.O.) BLOWER ACCESS PANEL INTERLOCK SWITCH, SPST-(N.O.) JUNCTION BOX LIGHT-EMITTING DIODE FOR STATUS CODES LOW GAS PRESSURE SWITCH, SPST-(N.O.) LIMIT SWITCH, AUTO RESET, (N.C.) AUTO-RESET INTERNAL MOTOR OVERLOAD TEMP. SW.
ALS1 BLWR BLWM CAP CPU DSS EAC-1 EAC-2 FRS FSE FU1 FU2 GV GVR HI/LO HSI HSIR HUM IDM IDR ILK JB LED LGPS LS OL
LEGEND
321257-401 REV. A
JUNCTION UNMARKED TERMINAL PCB TERMINAL FACTORY WIRING (115VAC) FACTORY WIRING (24VAC) FIELD WIRING (115VAC) FIELD WIRING (24VAC) CONDUCTOR ON PCB
PLUG RECEPTACLE FIELD SPLICE
NOTES:
1. IF ANY OF THE ORIGINAL EQUIPMENT WIRE IS REPLACED USE WIRE RATED FOR 105˚C. 2. INDUCER (IDM) AND BLOWER (BLWM) MOTORS CONTAIN INTERNAL AUTO-RESET THERMAL OVERLOAD SWITCHES (OL). 3. BLOWER MOTOR SPEED SELECTIONS ARE FOR AVERAGE CONDITIONS, SEE INSTALLATION INSTRUCTIONS FOR DETAILS ON OPTIMUM SPEED SELECTION. 4. USE ONLY COPPER WIRE BETWEEN THE DISCONNECT SWITCH AND THE FURNACE JUNCTION BOX (JB). 5. THIS WIRE MUST BE CONNECTED TO FURNACE SHEETMETAL FOR CONTROL TO DETECT FLAME. 6. FACTORY CONNECTED WHEN LGPS NOT USED. 7. REPLACE ONLY WITH A 3 AMP FUSE. 8. YELLOW LEAD NOT ON ALL MOTORS. 9. WHEN USED AUXILLARY LIMIT SWITCH (ALS) IS ON DOWNFLOW MODELS ONLY.
PRINTED CIRCUIT BOARD 9-CIRCUIT CONNECTOR 2-CIRCUIT PCB CONNECTOR 3-CIRCUIT IDM CONNECTOR 2-CIRCUIT JB CONNECTOR 2-CIRCUIT HSI/PCB CONNECTOR PRESSURE SWITCH, SPST-(N.O.) COMPONENT TEST PIN TRANSFORMER-115VAC/24VAC
PCB PL1 PL2 PL3 PL4 PL5 PRS TEST TRAN
FIELD WIRING SCREW TERMINAL FIELD GROUND EQUIPMENT GROUND
RED
3-P
2-C
1-M
NOTE
#5
GRN
C
PRS
NO
OL
START
BLWM
WHT (COM)
CAP -1
(LO)RED
NOTE #8
(HI)
(MED HI)
BLK
YEL
WHT
BRN
GRN
WHT (COM)
BRN
BLU (MED LO)
L2
COM
PR2 EAC-2
1.5 AMP
BLOWER
SPEED
SELECT
EAC-1
FUSE
FU1
24 VAC-3A
HEAT SPARE-2 COOL SPARE-1
90 SEC 135 SEC 180 SEC 225 SEC
BLOWER OFF DELAY SELECTION CHART
GVR
HSIR IDR BLWR
HI/LO
RELAY
ORN
YEL
NOTE #6
SEC-2SEC-1
WHT BLK
BLK
BLK
BLK
BLK
WHT
WHT
12
HSI
PL5
IDM
FUSED DISCONNECT
SWITCH (WHEN REQ'D)
NOTE #4
JB
WHT
BLK
GRN GRN
FU2
RED
BLU
FRS2
WHT FSE
RED
RED
PL1
LED
TEST
PCB BLOWER
OFF
DELAY
LS
3 2 1
1 2
PL3
PL2
120 VAC
PR1
L1
(WHEN USED)
LGPS
G
R
Y
W
C
HUM
123
6 987
45
(WHEN USED)
ALS
NOTE #9
TEST
LGPS
FRS2LS
(WHEN USED)
LS
NOTE #6
PL3
PL2 PL5
PL1
9
6
L2
FU1 NOTE #7
1 7 4
HUM
R
W
L1 OL
START
IDM
HEAT COOL
COM
NOTE #8
NOTE #4
EQUIPMENT GROUND
L1 L2
LO
HI
BLWR HSIR
IDR
CAP-1
BRN
BRN
LO
SPARE-2
SPARE-1
MED HI
HI
MED LO
COMGRN
EAC-1 EAC-2
11
BLWM
3
1
2 2
HSI
2
PR1 PR2
SEC-1 SEC-2
CPU
FSE
Y
G
C
8NOTE #5
GVR-2
DSS
GV
2-C
1-M
3 5
2
HI LO
HSIR IDR BLWR GVR
GVR-1
TRAN 24VAC
115VAC
SCHEMATIC DIAGRAM
(NATURAL GAS & PROPANE)
ILK
12
ALS
3-P
TRAN
BLU
WHT BLK
21
DSS
GV
PL4
ILK
PL4
TO 115VAC FIELD DISCONNECT
PRS
FRS1
FRS1
(WHEN USED)
—14—

The blower reverts to continuous operation after the heating cycle is completed.
When the thermostat "calls for cooling," the blower operates on cooling speed. When the thermostat is satisfied, the blower operates an
additional 90 sec before reverting back to continuous operation on heating speed.
4. Heat pump mode
When installed with a heat pump, the furnace control automatically changes the timing sequence to avoid long blower off time during
demand defrost cycles. When the W-Y or W-Y-G thermostat inputs are received at the same time, the control changes the blower to heating
speed or starts the blower if it was off, and begins a heating cycle. The blower remains on until the end of the prepurge period, then shuts
off until the end of the ignition warm up and trial for ignition periods (a total of 24 sec). The blower then comes back on at heating speed.
When the W input signal disappears, the control begins the normal inducer post-purge period and the blower changes to cooling speed after
a 1-sec delay. If the W-Y-G signals disappear at the same time, the blower remains on for the selected heating blower off delay period and
the inducer goes through its normal post-purge period. If the W-Y inputs should disappear, leaving the G signal input, the control goes into
continuous blower and the inducer remains on for the normal post-purge period.
Anytime the control senses false flame, the control locks out of the heating mode. This occurs because the control cannot sense the W input
due to the false flame signal and, as a result, sees only the Y input and goes into cooling mode blower off delay. All other control functions
remain in standard format.
NOTE: EAC-1 terminal is energized whenever blower operates. HUM terminal is only energized when gas valve is energized.
C. Start-up Procedures
1. Purge gas lines—After all connections have been made, purge the lines and check for leaks.
WARNING: Never purge a line into a combustion chamber. Never use matches, candles, flame or other sources of
ignition to check for gas leakage. Use a soap-and-water solution to check for gas leaks. Failure to follow this warning could
result in fire, explosion, personal injury, or death.
2. Component test—The furnace control allows all components, except gas valve, to be run for a short period of time.
This feature helps diagnose a system problem in case of a component failure. To initiate component test procedure, short (jumper) the TEST
1/4-in. quick connect terminal on control board (adjacent to diagnostic light) and the C terminal on thermostat connection block for
approximately 2 sec. (See Fig. 11.)
NOTE: Component test feature will not operate if any thermostat signal is present at control center.
Component test sequence is as follows.
a. Momentarily jumper TEST and C terminals until LED goes off.
b. LED will display previous fault 4 times.
c. Inducer motor operates for 10 sec, then stops.
d. Hot surface ignitor is energized for 15 sec, then de-energized.
e. Blower motor operates on cooling speed for 10 sec, then stops.
f. Blower motor operates on heating speed for 10 sec, then stops.
3. To operate furnace, follow procedures on operating instruction label attached to furnace.
4. With furnace operating, set thermostat below room temperature and observe that furnace goes off. Set thermostat above room temperature
and observe that furnace restarts.
D. Adjustments
1. Set gas input rate.
There are 2 methods of adjusting the gas input rate. The preferred method is by using Table 7 and following instructions in item a. The
second method is by clocking the gas meter and following instructions in item b.
The gas valve regulator has been nominally set at 3.5-in. wc for natural gas. When adjusting input rate, do not set manifold pressure above
3.8-in. wc or below 3.2-in. wc.
a. Check gas input rate using Table 7.
(1.) Obtain average yearly heat value for local gas supply.
(2.) Obtain average yearly specific gravity for local gas supply.
(3.) Verify furnace model. Table 7 can only be used for model GB3AAV Furnaces.
(4.) Check and verify orifice size in furnace. NEVER ASSUME THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.
CAUTION: DO NOT redrill burner orifices. Improper drilling (burrs, out-of-round holes, etc.) can cause excessive
burner noise and misdirection of burner flames. This can result in flame impingement of the burners and heat exchangers,
causing failure.
(5.) Find natural gas heat value and specific gravity in Table 7.
—15—
→

(6.) Follow heat value and specific gravity lines to point of intersection. Find orifice size and manifold pressure settings for proper
operation at given natural gas conditions.
EXAMPLE:
Heat value 1070 Btu/cu ft
Specific gravity 0.58
Therefore; Orifice No. 44 *
Manifold pressure 3.6-in. wc
* The furnace is shipped with No. 43 orifices. Therefore, in this example all main burner orifices must be changed and the manifold pressure
must be adjusted.
(7.) Proceed to item c. to adjust manifold pressure.
b. Check gas input rate by clocking gas meter.
Table 7—Model GB3AAV Orifice Size and Manifold Pressure for Correct Input Rate*
(Tabulated Data Based on Altitude Up to 2000 ft and 23,000 Btuh Per Burner)
GAS HEAT VALUE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.56 0.58 0.60 0.62 0.64 0.66 0.68 0.70 0.72
Orf
No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press. Orf No. Mnfld Press.
860 40 41
—
3.2
3.5
—
40
41
39
3.3
3.6
—
40
41
39
3.4
3.7
3.2
40
41
39
3.5
3.8
3.3
40
38
39
3.7
3.2
3.4
40
38
39
3.8
3.3
3.5
—
38
39
—
3.4
3.6
37
38
39
3.2
3.5
3.8
37
38
—
3.2
3.6
—
875 — 41
42
—
3.3
3.7
40
41
—
3.2
3.5
—
40
41
—
3.3
3.6
—
40
41
39
3.4
3.7
3.2
40
41
39
3.5
3.8
3.3
40
38
39
3.6
3.2
3.4
40
38
39
3.8
3.3
3.5
—
38
39
—
3.4
3.6
—
38
39
—
3.4
3.7
890 — 41
42
—
3.2
3.6
—
41
42
—
3.4
3.7
40
41
—
3.2
3.5
—
40
41
—
3.3
3.6
—
40
41
39
3.4
3.7
3.2
40
41
39
3.5
3.8
3.3
40
—
39
3.6
—
3.4
40
38
39
3.7
3.2
3.5
40
38
39
3.8
3.3
3.6
905 — —
42
—
—
3.5
—
41
42
—
3.2
3.6
—
41
42
—
3.4
3.7
40
41
—
3.2
3.5
—
40
41
—
3.3
3.6
—
40
41
39
3.4
3.7
3.2
40
41
39
3.5
3.8
3.3
40
—
39
3.6
—
3.4
40
38
39
3.7
3.2
3.5
920 — —
42
—
—
3.4
—
—
42
—
—
3.5
—
41
42
—
3.2
3.6
—
41
42
—
3.4
3.7
40
41
42
3.2
3.5
3.8
40
41
—
3.3
3.6
—
40
41
39
3.4
3.7
3.2
40
41
39
3.5
3.8
3.3
40
—
39
3.6
—
3.4
935 42 —
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
42
—
41
3.6
—
3.2
42
—
41
3.7
—
3.4
42
40
41
3.8
3.2
3.5
—
40
41
—
3.3
3.6
39
40
41
3.2
3.4
3.7
39
40
41
3.3
3.5
3.8
950 42 —
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
42
—
41
3.6
—
3.2
42
—
41
3.7
—
3.3
42
40
41
3.8
3.2
3.5
—
40
41
—
3.3
3.6
39
40
41
3.2
3.4
3.7
965 — 43
—
—
3.7
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
42
—
41
3.6
—
3.2
42
—
41
3.7
—
3.3
42
40
41
3.8
3.2
3.4
—
40
41
—
3.3
3.5
980 — 43
—
—
3.6
—
—
43
—
—
3.7
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
42
—
41
3.6
—
3.2
42
—
41
3.7
—
3.3
42
44
41
3.8
3.2
3.4
995 — 43
—
—
3.5
—
—
43
—
—
3.6
—
—
43
—
—
3.8
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
42
—
41
3.6
—
3.2
42
—
41
3.7
—
3.3
1010 — 43
—
—
3.4
—
—
43
—
—
3.5
—
—
43
—
—
3.6
—
—
43
—
—
3.6
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
42
—
41
3.6
—
3.2
1025 — 43
44
—
3.3
3.8
—
43
—
—
3.4
—
—
43
—
—
3.5
—
—
43
—
—
3.7
—
—
43
—
—
3.8
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
42
—
—
3.5
—
—
1035 — 43
44
—
3.2
3.7
—
43
44
—
3.3
3.8
—
43
—
—
3.4
—
—
43
—
—
3.6
—
—
43
—
—
3.7
—
—
43
—
—
3.8
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
42
—
—
3.4
—
—
1055 — —
44
—
—
3.6
—
43
44
—
3.2
3.7
—
43
44
—
3.3
3.8
—
43
—
—
3.5
—
—
43
—
—
3.6
—
—
43
—
—
3.7
—
—
43
—
—
3.8
—
42
—
—
3.2
—
—
42
—
—
3.3
—
—
1070 — —
44
—
—
3.5
—
—
44
—
—
3.6
—
43
44
—
3.3
3.7
—
43
44
—
3.4
3.8
—
43
—
—
3.5
—
—
43
—
—
3.6
—
—
43
—
—
3.7
—
—
43
—
—
3.8
—
42
—
—
3.2
—
—
1085 —
44 — 3.4 — 44 — 3.5 43 44 3.2 3.6 43 44 3.3 3.7 43 —3.4 —43 —3.5 —43 —3.6 —43 —3.7 —43 —3.8 —
1100 —
44 — 3.3 — 44 — 3.4 — 44 — 3.5 43 44 3.2 3.6 43 44 3.3 3.7 43 —3.4 —43 —3.5 —43 —3.6 —43 —3.7 —
*For size 060135 only, deduct 0.1-in. wc from manifold pressure shown in table due to 22,500 Btuh per burner input. If resultant manifold pressure falls below 3.2-in. wc,
change orifice size.
—16—

(1.) Obtain average yearly heat value for local gas supply.
(2.) Check and verify orifice size in furnace. NEVER ASSUME THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.
(3.) Turn off all other gas appliances and pilots.
(4.) Start furnace and let run for 3 minutes.
(5.) Measure time (in sec) for gas meter to complete 1 revolution.
(6.) Refer to Table 8 for cu ft of gas per hr.
(7.) Multiply gas rate (cu ft/hr) by heating value (Btu/cu ft).
EXAMPLE:
Btu heating input = Btu/cu ft X cu ft/hr
Heating value of gas = 1070 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 72 sec
Gas rate = 100 X 1070 = 107,000 Btuh
(8.) Check to make sure that measured gas input does not exceed gas input on unit rating plate.
(9.) Proceed to item c. to adjust manifold pressure.
c. Adjust gas input.
(1.) Remove regulator adjustment seal cap. (See Fig. 15.)
(2.) Turn adjusting screw counterclockwise to decrease input. Turn screw clockwise to increase input. DO NOT set manifold pressure
less than 3.2-in. wc or more than 3.8-in. wc for natural gas. Make any major adjustments by changing main burner orifices.
(3.) When correct input is obtained, replace regulator adjustment seal cap. Main burner flame should be clear blue, almost transparent.
(See Fig. 16.)
d. High altitude—In the United States, gas input on unit rating plate is for altitudes up to 2000 ft. Ratings for altitudes over 2000 ft must
be 4 percent less for each 1000 ft above sea level. To obtain the adjusted altitude rating, adjust the manifold pressure, item c., and replace
the main burner orifices as needed. Refer to NFGC Appendix F, Table F-4 for proper orifice sizing at high altitudes.
e. Canadian installations only—The Canadian ratings are approved for altitudes up to 2000 ft for natural and propane gases. High-altitude
ratings are from 2000 ft to 4500 ft above sea level. See Table 9 for nominal burner orifice size. High-altitude input ratings include a 10
percent derated as required by Canadian standards.
2. Set temperature rise.
Furnace must operate within range of temperature rise specified on the unit rating plate. Determine the air temperature rise as follows.
a. Place duct thermometers in return and supply ducts as near furnace as possible. Be sure thermometers do not "see" heat exchangers so
that radiant heat does not affect thermometer readings. This is particularly important with straight-run ducts.
b. When thermometer readings stabilize, subtract return-air temperature from supply-air temperature to determine temperature rise.
Fig. 15—Redundant Automatic Gas Control Valve A90044
OFF
MANIFOLD
PRESSURE TAP
CONTROL
KNOB
GAS
PRESSURE
REGULATOR
ADJUSTMENT
INLET
PRESSURE TAP
—17—
→

Fig. 16—Burner Flame A89020
Table 8—Gas Rate (Cu Ft/Hr)
SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL
1
cu ft 2 cu ft 5 cu ft 1 cu ft 2 cu ft 5 cu ft
10
11
12
13
14
360
327
300
277
257
720
655
600
555
514
1800
1636
1500
1385
1286
50
51
52
53
54
72
71
69
68
67
144
141
138
136
133
360
355
346
340
333
15
16
17
18
19
240
225
212
200
189
480
450
424
400
379
1200
1125
1059
1000
947
55
56
57
58
59
65
64
63
62
61
131
129
126
124
122
327
321
316
310
305
20
21
22
23
24
180
171
164
157
150
360
343
327
313
300
900
857
818
783
750
60
62
64
66
68
60
58
56
54
53
120
116
112
109
106
300
290
281
273
265
25
26
27
28
29
144
138
133
129
124
288
277
267
257
248
720
692
667
643
621
70
72
74
76
78
51
50
48
47
46
103
100
97
95
92
257
250
243
237
231
30
31
32
33
34
120
116
113
109
106
240
232
225
218
212
600
581
563
545
529
80
82
84
86
88
45
44
43
42
41
90
88
86
84
82
225
220
214
209
205
35
36
37
38
39
103
100
97
95
92
206
200
195
189
185
514
500
486
474
462
90
92
94
96
98
40
39
38
38
37
80
78
76
75
74
200
196
192
188
184
40
41
42
43
44
90
88
86
84
82
180
176
172
167
164
450
439
429
419
409
100
102
104
106
108
36
35
35
34
33
72
71
69
68
67
180
178
173
170
167
45
46
47
48
49
80
78
76
75
73
160
157
153
150
147
400
391
383
375
367
110
112
116
120
33
32
31
30
65
64
62
60
164
161
155
150
—18—

c. Adjust air temperature rise by adjusting blower speed. Increase blower speed to reduce temperature rise. Decrease blower speed to
increase temperature rise.
WARNING: Disconnect the electrical power before changing the speed tap. Failure to follow this warning could result
in personal injury.
d. To change blower motor speed selections for heating mode, remove blower motor lead from control board HEAT terminal. (See Fig.
11.) Select desired blower motor speed lead from 1 of the other terminals and relocate it to HEAT terminal. See Table 10 for lead color
identification. Reconnect original lead on SPARE terminal.
Follow this same procedure for proper selection of COOL speed selection.
CAUTION: Recheck temperature rise. It must be within limits specified on unit rating plate. Recommended operation
is at midpoint of rise or above.
3. Set thermostat heat anticipator.
The thermostat heat anticipation must be set to match the amp draw of the electrical components in the R-W circuit. Accurate amp draw
readings can be obtained at thermostat subbase terminals R and W. Fig. 17 illustrates an easy method of obtaining the actual amp draw.
The amp reading should be taken after the blower motor has started. See the thermostat manufacturer’s instructions for adjusting the heat
anticipator and for varying the heating cycle length.
NOTE: When using an electronic thermostat, set cycle rate for 3 cycles per hr.
E. Check Safety Controls
The flame sensor, gas valve, and pressure switch were all checked in the Start-up Procedures section as part of normal operation.
1. Check primary limit control.
This control shuts off the combustion control system and energizes the circulating-air blower motor if the furnace overheats.
The preferred method of checking the limit control is to gradually block off the return air after the furnace has been operating for a period
of at least 5 minutes. As soon as the limit has shut off the burners, the return-air opening should be unblocked. By using this method to
check the limit control, it can be established that the limit is functioning properly and operates if there is a motor failure.
2. Check draft safeguard switch.
The purpose of this control is to permit the safe shutdown of the furnace during certain blocked vent conditions.
Table 9—Canadian Orifice Size
GAS SEA LEVEL 0-2000 FT HIGH ALTITUDE
2000-4500 FT
Natural 43 44
Propane 54 55
Table 10—Speed Selector
COLOR SPEED FACTORY
ATTACHED TO
Black High COOL
Yellow
(When present) Medium-High SPARE
Blue Medium-Low HEAT
Red Low SPARE
White Common COM
Fig. 17—Amp Draw Check With Ammeter A80201
R Y W G
10 TURNS
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
HOOK-AROUND
VOLT/AMMETER
EXAMPLE: 5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS = 0.5 AMPS FOR THERMOSTAT SETTING
FROM UNIT 24-VOLT
TERMINAL BLOCK
—19—

a. Disconnect power to furnace and remove vent connector from furnace outlet collar. Be sure to allow time for vent pipe to cool down
before removing.
b. Restore power to furnace and set room thermostat above room temperature.
c. After normal start-up, allow furnace to operate for 2 minutes, then block flue outlet 100 percent. Furnace should cycle off within 2
minutes.
d. Remove blockage and reconnect vent pipe to furnace outlet collar.
e. Wait 5 minutes and then reset draft safeguard switch.
3. Check pressure switch.
This control proves operation of draft inducer blower.
a. Turn off 115-v power to furnace.
b. Remove control door and disconnect inducer motor lead wires from wire harness.
c. Turn on 115-v power to furnace.
d. Set thermostat to "call for heat" and wait 1 minute. When pressure switch is functioning properly, hot surface ignitor should NOT glow
and control center diagnostic light flashes a 31 fault. If hot surface ignitor glows when inducer motor is disconnected, shut down furnace
immediately. Determine reason pressure switch did not function properly and correct condition.
e. Turn off 115-v power to furnace.
f. Reconnect inducer motor wires, replace control door, and turn on 115-v power to furnace.
4. Check auxiliary limits (when used).
a. Turn off 115-v power to furnace.
b. Remove blower access door.
c. Disconnect red motor lead at blower speed selector. Mark terminal for proper re-connection.
d. Replace blower access door.
e. Turn on 115-v power to furnace. Be sure room thermostat is calling for heat.
f. Allow furnace to operate until auxiliary limit activates, but DO NOT operate furnace longer than 4 minutes.
g. If furnace operates for 4 minutes, check/replace limit switch(es).
h. Turn off 115-v power to furnace.
i. Remove blower access door.
j. Reconnect red motor lead, reset switch, and replace door.
k. Turn on 115-v power to furnace.
F. Checklist
1. Put away tools, instruments, and clean up debris.
2. Verify manual reset switches have continuity.
3. Ensure blower and control access doors are properly installed.
4. Cycle test furnace with room thermostat.
5. Check operation of accessories per manufacturer’s instructions.
6. Review User’s Manual with owner.
7. Leave literature packet near furnace.
© 1994 RESCO P.O. Box 1667, Indianapolis, IN 46206 45003r —20— Catalog No. 92-33GB-3A5
→