Allied Air Enterprises Upflow User Manual

AFFIX LABEL HERE

INSTALLATION AND SERVICING INSTRUCTIONS

UPFLOW, DOWNFLOW OR HORIZONTAL

TWO STAGE HEAT VARIABLE SPEED

GAS-FIRED NON-CONDENSING

WARM AIR FURNACE

TABLE OF CONTENTS

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Issue 0527

Gas Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Furnace Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Furnace Wiring Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Location/Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Air for Combustion & Ventilation . . . . . . . . . . . . . . . . . . . . . . . . 8

Ducting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE

Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.

Installation and service must be performed
by a qualified installer, service agency or
the gas supplier. Installation by an
unqualified person may lead to equipment
damage and/or a hazardous condition
which may cause bodily injury and harm
and, as such, at the sole discretion of the
manufacturer, the entire warranty may be
voided and be of no further force and
effect.

Control Board & Variable Speed Motor Features . . . . . . . . . . . . . 17

Unit Sequence of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Start-Up Operation & Checkout . . . . . . . . . . . . . . . . . . . . . . . . . 19

Sequence of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Servicing The Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Control System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

WHAT TO DO IF YOU SMELL GAS:

• Do not try to light any appliance.

• Extinguish any open flame.

• 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.

20571201 Issue 0527 Page 1 of 28

SAFETY

The following is a list of safety precautions and their locations in this manual.

These safety rules and precautions must be followed when installing this furnace.

1. Use only with type of gas approved for this furnace. Refer to the furnace rating
plate.

2. Install this furnace only in a location and position as specified in The

Location/Placement Section on page 7 of these instructions.

3. Provide adequate combustion and ventilation air to the furnace space as
specified in Air for Combustion and Ventilation section on page 8 of these
instructions.

4. Combustion products must be discharged outdoors. Connect this furnace to an
approved vent system only, as specified in Venting on page 12 of these
instructions.

5. Never test for gas leaks with an open flame. Use a commercially available
soap solution made specifically for the detection of leaks to check all
connections, as specified in The Gas Connection section on page 16 of these
instructions.

6. Always install furnace to operate within the furnace's intended temperature-rise
range with a duct system which has an external static pressure within the
allowable range, as specified in Furnace Specifications on page 3 of these
instructions. See furnace rating plate.

7. When a furnace is installed so that supply ducts carry air circulated by the
furnace to areas outside the space containing the furnace, the return air shall
also be handled by duct(s) sealed to the furnace casing and terminating outside
the space containing the furnace. See page 11 for Ducting.

8. A gas-fired furnace for installation in a residential garage must be installed as
specified in The Location / Placement section on page 7 of these instructions.

9. It is not recommended that this furnace be used as a construction heater during
any phase of construction. Very low return air temperatures, harmful vapors
and operation of the unit with clogged or misplaced filters will damage the unit.
The unit may only be used for heating of buildings or structures under
construction, if the conditions listed on page 6 in the "Introduction" section of

these instructions are met.

20571201 Issue 0527 Page 2 of 28

FURNACE SPECIFICATIONS

UNIT DIMENSIONS

MODEL

AV050B3 29 1/2 13 1/2 38 1/4 11 1/2 20 3/8 12 21 5/8 4 15 9.9 14 30 - 60 40 - 70 105
AV075B3 29 1/2 13 1/2 38 1/4 11 1/2 20 3/8 12 21 5/8 4 15 9.9 14 30 - 60 40 - 70 113
AV100B4 29 1/2 17 38 1/4 15 20 3/8 15 1/2 21 5/8 4 15 11.7 14 30 - 60 40 - 70 141
AV125B5 29 1/2 20 1/2 38 1/4 18 1/2 20 3/8 19 21 5/8 4 20 11.7 14 30 - 60 40 - 70 167

LENGTH WIDTH HEIGHT

A B C D E F G H

DUCT SUPPLY

OPENING

DUCT RETURN

OPENING

VENT

PIPE

DIA.

MAX. OVER

CURRENT

PROTECTION

AMPS

MAX.
UNIT

ELECTRICAL
SUPPLY MIN.

WIRE

SIZE(AWG)

TEMPERATURE

RISE

RANGE

LOW

FIRE

HIGH

FIRE

WEIGHT

* REDUCER SUPPLIED WITH FURNACE WHEN CONNECTION SIZE

IS DIFFERENT THAN PIPE DIA. REQUIRED (H) FOR FLUE VENT
PIPE.

NET

LBS

20571201 Issue 0527 Page 3 of 28

BLOWER MOTOR SPECIFICATIONS AND AIRFLOW ADJUSTING DATA

Adjusting Airflow

HEAT SETTINGS COOL SETTINGS

MODEL

AV050B3 1/2 10 X 6 525 425 325 625

AV075B3 1/2 10 X 6 740 640 540 840

AV100B4 3/4 12 X 9 1250 1150 1050 1350

AV125B5 3/4 12 X 12 1650 1550 1450 1750

THE UNIT, AS SHIPPED, IS FACTORY SET AT SETTING "A" TO RUN AT THE MIDDLE OF THE HEATING RISE RANGE SHOWN ON THE
UNIT RATING LABEL.

MOTORHPBLOWER

WHEEL

HEATING CFM @ .50 STATIC COOL CFM @ .50 STATIC

SETTING

"A"

SETTING

"B"

SETTING

"C"

SETTING

"D"

COOLING

ADJUSTMENT

NORM

( + )

( - )

NORM

( + )

( - )

NORM

( + )

( - )

NORM

( + )

( - )

SETTING

"A"

1200
1380
1020

1200
1380
1020

1600
1800
1360

2000
2200
1700

SETTING

"B"

1000
1150

850

1000
1150

850

1400
1610
1190

1800
2070
1530

SETTING

"C"

800
920
680

800
920
680

1200
1380
1020

1600
1840
1360

SETTING

"D"

600
690
510

600
690
510

1000
1150

850

1400
1610
1190

When operating the furnace in the heating mode, the static pressure and the temperature rise (supply air temperature
minus return air temperature) must be within those limits specified on the rating label. Failure to follow this warning
could lead to severe furnace damage.

Turn OFF all gas and electrical power to furnace before performing any maintenance or service on unit. (Unless
specific test requires gas and electrical supplies.) Failure to take this precaution may result in personal injury due
to electrical shock or uncontrolled gas leakage.

20571201 Issue 0527 Page 4 of 28

FURNACE WIRING SPECIFICATIONS

20571201 Issue 0527 Page 5 of 28

The furnace cabinet must have an uninterrupted or unbroken electrical ground to minimize personal injury if an
electrical fault should occur. The unit must also be electrically grounded in accordance with local codes, or in the
absence of local codes, with the latest edition of the (U.S.) National Electrical Code ANSI/NFPA No. 70 or CSA
Standard C22.1; Part 1 Canadian Electrical Code, if an external electrical source is utilized. DO NOT use gas piping
as an electrical ground.

INTRODUCTION

This furnace is design certified by CSA International as a Category I furnace using air from inside the structure for

combustion.

It is shipped as a packaged unit, complete with burners and controls, and requires a line voltage (115V) connection to

the junction box, a thermostat hook-up as per the wiring diagram and a gas line connection, ducting and flue piping. This

furnace can be installed in either upflow, downflow or horizontal airflow positions, at no time should this unit be
operated on its back. The design of this furnace is NOT CSA Certified for installation in recreation vehicles, in
manufactured (mobil) homes, outdoors or as a construction heater.

This furnace has been designed to interface with split system cooling equipment (approved by a nationally recognized
testing laboratory) so as to provide "year round air conditioning". The blower has been sized for both heating and cooling
and the furnace controls include a cooling fan relay.

The furnace installation must conform with local building codes or in the absence of local codes, with the latest edition
of the (U.S.) National Fuel Gas Code ANSI Z223.1 (NFPA-54) or Canadian Natural Gas and Propane Installation Codes
CSA B149.1.

For complete information on installation standards consult the (U.S.) National Fuel Gas Code, obtainable from the
National Fire Protection Association, Inc., Batterymarch Park, Quincy, MA 02269 or the American Gas Association, 1515
Wilson Boulevard Arlington, VA 22209 or the Canadian installation codes obtainable from Canadian Standards Association,
178 Rexdale Boulevard, Etobicoke, Ontario, Canada M9W 1R3.

This furnace is designed for 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 must not exceed a maximum continuous
temperature of 85°F dB.

The furnace may be used for heating of buildings or structures under construction, if the following conditions are met:

• The vent system must be permanently installed per these instructions.

• A room thermostat must control the furnace. The use of fixed jumpers that will provide continuous heating is not
allowed.

• The return air duct must be provided and sealed to the furnace.

• Return air temperature range between 60° F and 80° F must be maintained.

• Air filters must be installed in the system and must be maintained during construction.

• Air filters must be replaced upon construction completion.

• The input rate and temperature rise must be set per the furnace rating plate.

• One hundred percent (100%) outdoor air must be provided for combustion air requirements during construction.
Temporary ducting may supply outdoor air to the furnace. Do not connect combustion air duct directly to the
furnace. Size the temporary duct following these instructions in the section "Air for Combustion & Ventilation" for
air in a confined space with air from outside.

• The furnace heat exchanger, components, duct system, air filters and evaporator coils must be thoroughly cleaned
following final construction clean-up.

• All furnace operating conditions (including ignition, input rate, temperature rise and venting) must be verified
according to these installation instructions.

These instructions are written for individual residential installation only. For multi-unit installation or

commercial applications, please contact manufacturer for recommendations.

20571201 Issue 0527 Page 6 of 28

LOCATION / PLACEMENT

Site Selection: This furnace may be located in an attic, closet, basement, crawl space, alcove or suspended from the

ceiling of a utility room or basement. Select a location that will meet all requirements for safety,
clearances, ventilation and combustion air, ductwork design, gas piping, electrical wiring and venting.

Clearances: The following minimum clearances, or greater, must be provided between the furnace and adjacent

construction.

TABLE 1 MINIMUM INSTALLATION CLEARANCES

"UPFLOW" POSITION "DOWNFLOW" POSITION "HORIZONTAL" POSITION

Suitable for alcove or closet
installation† on combustible
flooring at minimum
clearance from adjacent
construction not less than
the following:

Top Sides Back Front Vent

2" 1" 1" 6" 6" with single wall vent
2" 1" 1" 3" 1" with B1 vent

† For closet installation see Air for Combustion and Ventilation.

Suitable for alcove or closet installation† on non­combustible flooring at minimum clearance from
adjacent construction not less than the following:
* Installation on combustible flooring only when
installed on special base (see model & rating label
for proper special base).

Suitable for attic, alcove or closet installation† on
combustible flooring at minimum clearance from
adjacent construction not less than the following:
* Line contact only permissible between lines
formed by intersection of the top and two sides of
the furnace jacket and building joist, studs, or
framing.

Failure to comply with all of the clearances will
create a fire hazard.

INSTALLATION POSITIONS

flooring, on wood flooring in the upflow or horizontal
positions, however, it must not be installed directly on

carpeting, tile or any other combustible material. In

the downflow position, it must be installed on non­combustible flooring, on the special base listed on the
rating label OR on a cased coil.

In a horizontal position, line contact with combustibles
is only permissible between lines formed by the
intersection of the furnace top, the front and back sides,
and building joists, studs or framing (See Figure 1).

Figure 1

HORIZONTAL LINE CONTACT

Furnace must not lean back. It must be level or
tilt up to 2° to the front. (See Figure 1.)

The furnace should also be located as near to the
center of the air distribution system as possible, and
should be installed level.

This furnace may be installed on non-combustible

20571201 Issue 0527 Page 7 of 28

A clearance of at least 30" should be provided at the
front of the unit for servicing. For attic installations, the
passageway and servicing area adjacent to the furnace
should be floored.

If the furnace is to be installed in a crawl space,
consult local codes. (Use of a concrete pad 1" to 2" thick
is recommended.)

If the furnace is to be suspended from the ceiling, it
will be necessary to use steel pipe straps around each
end of the furnace. These straps should be attached to
the furnace with sheet metal screws and to the rafters
with bolts. The furnace may also be suspended by using
an angle iron frame bolted to the rafters. (See Table on
page 3 for size and weight of furnace.) Care must be
taken to allow for service access.

If a furnace is to be installed in a residential garage,
it must be installed so the burners and the ignition source
are located not less than 18" above the floor and the
furnace must be located or protected to avoid physical
damage by vehicles.

AIR FOR COMBUSTION AND VENTILATION

Do not place combustible material on the furnace
jacket. Failure to comply with this warning will
create a fire hazard.

This furnace is not watertight and is not designed
for outdoor installation. This furnace shall be
installed in such a manner as to protect the
electrical components from water. Outdoor
installation would lead to a hazardous electrical
condition and to premature furnace failure.

Contaminated Combustion Air:

This furnace is not to be installed in a structure
defined as having contaminated combustion air. Allowing
exposure to substances containing chlorine or fluoride
could harm the furnace and void the warranty.
Substances to avoid include, but are not limited to:

• Permanent wave solutions

• Chlorinated waxes and cleaners

• Chlorine based swimming pool chemicals

• Water softening chemicals

• De-icing salts or chemical

• Carbon tetrachloride

• Halogen type refrigerants

• Cleaning solvents (such as perchloroethylene)

• Printing inks, paint removers, varnishes, etc.

• Hydrochloric acid

• Cements and glues

• Antistatic fabric softeners for clothes dryers

• Masonry acid washing materials

• Unrefined gases

Contaminated combustion air may cause premature
failure of the heat exchanger that may lead to a
hazardous condition and/or bodily harm, or loss of
life.

Adequate Ventilation and Combustion Air:

This section is provided to give guidelines for the
introduction of air for ventilation and combustion air. The
total quantity of air provided to the installation area must
equal the requirements of all gas appliances in the area.

Adequate facilities for providing air for combustion

and ventilation must be provided in accordance with the
latest edition of the National Fuel Gas Code ANSI
Z223.1/NFPA54 or CSA B149.1 Natural Gas and Propane
Installation Codes, or applicable provisions of the local
building codes.

The furnace shall be installed in a location in which
the facilities for ventilation permits satisfactory combustion
of gas, proper venting and maintenance of ambient
temperature at safe limits under normal conditions of use.
The furnace shall be located so as not to interfere with
proper circulation of air.

In addition to air needed for combustion, ventilation in
the form of process air must be provided as required for:
cooling of equipment or material, controlling dew point,
heating, drying, oxidation or dilution, safety exhaust and
odor control. Air must be supplied for ventilation,
including all air required for comfort and proper working
conditions for personnel.

For purposes of this instruction the following
definitions apply:

Confined Space: A space whose volume is less

than 50 cubic feet per 1000
Btu/hr of the aggregate input
rating of all appliances installed
in that space.

Unconfined Space: A space whose volume is not

less than 50 cubic feet per 1000
Btu/hr of the aggregate input
rating of all appliances installed
in that space. Rooms
communicating directly with the
space in which the appliances
are installed, through openings
not furnished with doors, are
considered a part of the
unconfined space.

20571201 Issue 0527 Page 8 of 28

If the installation area meets the definition of
"Unconfined Space" and does not have additional air
requirements as described, the furnace may be installed
without making special provisions for combustion and
ventilation air.

Do not block the combustion or ventilation air
openings in the furnace. Any blockage will result in
improper combustion and may result in a fire
hazard or unsafe condition.

Whenever this furnace is installed in an area along
with one or more gas appliances, the total Btu/hr
input of all appliances must be included when
determining the free area requirements for
combustion and ventilation air openings.

If ventilation and/or combustion air must be supplied to the "Confined Space" from inside the building structure, two
permanent openings to an additional room of sufficient volume as to combine the volumes of the spaces to meet the
criteria for an "Unconfined Space" must be created. Each opening must have a free area of not less than one square
inch per 1000 Btu per hour of total input of all appliances within the "Confined Space" (but not less than 100 square
inches). These openings must be located 12 inches from the top and bottom of the furnace area respectively and must
be at least 3 inches long on the smaller side of the opening (See Figure 2). Neither opening can be blocked at any time.

Figure 2 CONFINED SPACE / INDOOR AIR

TOTAL INPUT

(Btuh)

40,000
60,000

80,000
100,000
120,000
140,000
160,000

EXAMPLE:

50,000 Btuh Furnace & 10,000 Btuh Water
Heater = 60,000 Btuh Total Input = 12"
Dia. Round Duct.

MIN. FREE AREA

(Sq. In.)

100
100
100
100
120
140
160

ROUND DUCT

(Dia. In.)

12
12
12
12
13
14
15

If ventilation and/or combustion air must be supplied to the "Confined Space" from outside the building structure,
two permanent openings to the outdoors must be created. Each opening must have a free area of not less than one
square inch per 4000 Btu per hour of total input of all appliances within the "Confined Space". These openings must
be located 12 inches from the top and bottom of the furnace area respectively (See Figures 3, 4, and 5). Neither
opening can be blocked at any time.

Figure 3 CONFINED SPACE / OUTDOOR AIR

TOTAL INPUT

(Btuh)

40,000
60,000

80,000
100,000
120,000
140,000
160,000

MIN. FREE AREA

(Sq. In.)

10
15
20
25
30
35
40

ROUND DUCT

(Dia. In.)

4
5
5
6
6
7
8

EXAMPLE:

50,000 Btuh Furnace & 10,000 Btuh Water
Heater = 60,000 Btuh Total Input = 5" Dia.
Round Duct.

20571201 Issue 0527 Page 9 of 28

Figure 4

Figure 5

CONFINED SPACE / OUTDOOR AIR

FROM ATTIC

CONFINED SPACE / OUTDOOR AIR

FROM ATTIC & CRAWL SPACE

When horizontal ducts are used to supply air from the
outdoors, 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 air ducts must not
be less than 3 inches. Each opening must have a free
area of not less than one square inch per 2,000 Btu per
hour of total input of all appliances within the "Confined
Space". These openings must be located 12 in. from the
top and bottom of the furnace area. Neither opening can
be blocked at any time (See Figure 6).

Figure 6

CONFINED SPACE / OUTDOOR

AIR THROUGH HORIZONTAL DUCTS

Furnaces installed with combustion air drawn from
a heated space which includes exhaust fans,
fireplaces, or other devices that may produce a
negative pressure should be considered confined
space installations.

For an attic installation it is important to keep
insulation 12" or more away from any furnace
openings. Some types of insulating materials may
be combustible.

20571201 Issue 0527 Page 10 of 28

DUCTING

The proper sizing of warm air ducts is necessary to insure satisfactory heating operation. Ductwork should be in
accordance with the latest editions of (U.S.) NFPA-90A (Air Conditioning Systems) and NFPA-90B (Warm Air Heating
and Air Conditioning Systems) or Canadian equivalent.

Ductwork Recommendation:

The supply duct work should be attached to the
flanged opening provided at the discharge end of the
furnace. See page 3 "Furnace Specificatons" for the
dimensions of this opening.

A left, right, or bottom return air opening must be
used as determined by the layout of the installation. The

back must not be cut out for return connections. An

externally mounted air filter is required.

This furnace has a two piece bottom panel. For
bottom or end duct return, remove the back portion of the
bottom panel by removing the four (4) screws - two (2) on
each side toward the back of the furnace (See Figure 7).
Tilt furnace toward the front, the back portion of the panel
will drop down. Then the back portion can be removed
by pulling toward the back of the furnace.

Figure 7

BOTTOM PANEL REMOVAL

be of such a size that the heat exchanger can be
viewed for possible openings using light assistance or
a probe can be inserted by sampling the air stream.
The access panel shall be designed so as to prevent
leaks when locked in position. If an air conditioning
coil is installed, the access panel to the coil can be
used for this purpose.

When supply ducts carry air circulated by the
furnace to areas outside the spaces containing the
furnace, the return air shall also be handled by a
duct sealed to the furnace casing and terminating
outside the space containing the furnace. Incorrect
ductwork termination and sealing will create a
hazardous condition that could lead to bodily harm.

Air openings, intake and outlet pipes, return air
grilles and warm air registers must not be
obstructed.

Knockouts are provided on both sides of the furnace
to facilitate the cutout required to the return air ductwork.

Furnace cutouts must be the full size specified by the
corner markers. Undersized cutouts will adversely
affect the airflow capability of the furnace and could
cause overheating of the heat exchanger.

The following recommendations should be followed
when installing the ductwork:

1. Install locking-type dampers in all branches of the

individual ducts to balance out the system. Dampers

should be adjusted to impose the proper static at the

outlet of the furnace.

2. Noncombustible flexible duct connectors are

recommended to connect both the supply and return

ducts to the furnace.

3. In cases where the return air grille is located close to

the blower inlet, there should be at least one 90° air

turn between blower and return grille. Further

reduction in sound can be accomplished by installing

acoustical air turning vanes and/or lining the inside of

the duct with acoustical material.

4. It is recommended that the supply duct be provided

with a removable access panel. This opening shall

be accessible when the furnace is installed and shall

To Convert to Downflow Position:

1. Convert the combustion blower to side flue exit, as
outlined on page 14.

2. Install proper special base per Table 2 for installation
on combustible flooring (follow instructions supplied
with special base).

3. It is recommended that the return air be connected to
the bottom panel of the furnace when it is installed in
the downflow position.

NOTE: SPECIAL SUB-BASE NOT REQUIRED WHEN

FURNACE IS MOUNTED ON A METAL CASED
EVAPORATOR COIL.

Table 2

SPECIAL BASE INSTALLATION

MODEL

AV050B3
AV075B3

AV100B4 20066502 68L78
AV125B5 20066503 68L79

NOTE: Installation on combustible flooring only when

SPECIAL BASE

NUMBER

20066501 68L77

CAT. NO.

installed on one of the above listed special bases
or as identified on the furnace model and rating
label.

20571201 Issue 0527 Page 11 of 28

Filters:

Air filters must be used in every installation. For side
return installations, air filters must be installed external to
the furnace casing. An external filter rack kit with filter
(parts No. 20069901 or Cat. No. 68L75 12 / 15½" x 25"
sizes and 20069902 or Cat. No. 68L76 for 15½" / 19" x
25" sizes) is available as an optional accessory.

For bottom (end) return installations, the above
optional external rack may be used, if the unit was not
provided with a internal filter. Minimum filter size and
suggested filter materials are shown in Table 3. (If
different type filter is used, it must be an equivalent high
airflow capacity.)

Table 3 EXTERNAL FILTER RACK SIZE

MODEL

050-3
075-3

100-4 15 ½ X 25 15 ½ X 25
125-5 15 ½ X 25 19 X 25

SIDE

RETURN

15 ½ X 25 12 X 25

BOTTOM/END

RETURN

This furnace may use either a disposable filter,
permanent filter, electronic or high efficiency media air
cleaner. Consult filter/cleaner manufacturers for
maintience service and static pressure drop for air moving
requirements.

When installing the furnace with cooling equipment for
year round operation, the following recommendations
must be followed for series or parallel air flow:

1. In series flow applications, the evaporator coil is

mounted after the furnace in an enclosure in the

supply air stream. The furnace blower is used for

both heating and cooling airflow.

2. In parallel flow installation, dampers must be provided

to direct air over the furnace heat exchanger when

heat is desired and over the cooling when cooling is

desired. At no time may the evaporator coil be

located on the return air side of the heat exchanger.

IMPORTANT: The dampers should be adequate to

prevent cooled air from entering the
furnace, and if manually operated, must
be equipped with means to prevent
operation of either the cooling unit or
furnace unless the damper is in the full
cool or full heat position.

The coil MUST be installed on the air discharge
side of the furnace. Under no circumstances
should the air flow be such that cooled, conditioned
air can pass over the furnace heat exchanger. This
will cause condensation in the heat exchanger and
possible failure of the heat exchanger that could
lead to a fire hazard and/or hazardous conditions
that may lead to bodily harm. Heat exchanger
failure due to improper installation will not be
covered by warranty.

VENTING

Venting for this category I furnace must be to the
outside and in accordance with local codes or
requirements of the local utility. In the absence of local
codes, venting must conform to the applicable sections of
the latest edition of the (U.S.) National Fuel Gas Code
ANSI Z223.1/NFPA54, and/or CSA B149.1 Natural Gas
and Propane Installation Codes, and the vent
manufacturers instructions.

This furnace is CSA International certified as a
Category I forced air appliance and can not be vented

into a vent system with any Category II, III or IV
appliance. It must be vented vertically, or nearly

vertically, unless installed with a listed mechanical venter
in accordance with horizontal venting instructions. It must
not be connected to any portion of a mechanical draft
system operating under positive pressure

The 3" (in.) to 4" (in.) vent adaptor coupling (supplied
with unit) MUST BE USED. It must be connected directly
to the outlet of the combustion blower using a field
supplied corrosion resistant sheet metal screw (See
Figure 8).

Figure 8

VENT ADAPTOR MOUNTING

Pre-Installation Vent System Inspection:

Before this furnace is installed, it is highly
recommended that any existing vent system be
completely inspected.

For a chimney or "B" vent, this should include the
following:

1. Inspection for any deterioration in the chimney or "B"

20571201 Issue 0527 Page 12 of 28

vent. If deterioration is discovered, the chimney must
be repaired or the "B" vent must be replaced.

2. Inspection to ascertain that the vent system is clear
and free of obstructions. Any blockage must be
cleared before installing this furnace.

3. Cleaning the chimney or "B" vent if previously used
for venting a solid fuel burning appliance or fireplace.

4. Confirming that all unused chimney or "B" vent
connections are properly sealed.

5. Verification that the chimney is properly lined and
sized per the applicable codes.

Masonry Chimney:

This furnace can be common vented into an existing

tile lined masonry chimney provided:

1. The chimney is currently serving at least one
drafthood equipped appliance.

2. The vent connectors and chimney are sized in
accordance with the applicable sections of the (U.S.)
National Fuel Gas Code ANSI Z223.1/NFPA54,
and/or CSA B149.1 Natural Gas and Propane
Installation Codes.
This furnace must NOT vented ALONE into an

existing masonry chimney (either tile lined or unlined)
unless the chimney is also lined with either a type B vent
system or a listed single wall, metal lining system. Both
of these systems must be sized in accordance with the
applicable sections of the (U.S.) National Fuel Gas Code
ANSI Z223.1/NFPA54, and/or CSA B149.1 Natural Gas
and Propane Installation Codes.

Before venting this furnace into a chimney, check the

chimney for deterioration and repair if necessary. This
furnace must not be vented into a chimney serving a
separate appliance designed to burn solid fuel. Type"B"
vent connectors must be used on all installations and it
must be sized per the applicable sections of the (U.S.)
National Fuel Gas Code ANSI Z223.1/NFPA54, and/or
CSA B149.1 Natural Gas and Propane Installation Codes.

Type "B" Vent:

The furnace is also approved for use with a "B" vent

that terminates through the roof. Refer to the applicable
sections of the (U.S.) National Fuel Gas Code ANSI
Z223.1/NFPA54, and/or CSA B149.1 Natural Gas and
Propane Installation Codes for proper sizing and set-up
of this furnace with "B" vent for a dedicated vent system
or a common vented system.

Horizontal Venting:

This furnace is design certified by CSA International

for horizontal venting through an outside wall by use of
one of the following auxiliary draft inducer kits:

Table 4 AUXILIARY DRAFT INDUCERS

Vent Kit MFR Model * Furnace Input

Field Controls Co.

Tjernlund Products Inc.

* See rating label on this furnace for input

Vent Length: Max. 60 ft. - Min. 12 ft.

Follow instructions included with venting kit for proper installation and setup.

SWG-4G

SS1 OR SS1C

GPAK-J 50000, 75000 or 100000

GPAK-1 100000 or 125000

Vent Diameter: 4 in.

50000, 75000, 100000 or

125000

50000, 75000, 100000 or

125000

Location Requirements for Horizontal Venting:

Locate the vent terminal adhering to the following
minimum clearances and as specified in the auxiliary draft
inducer vent kit:

1. Vent terminal must be located at least one (1') foot

above the grade or at least one (1') foot above the

normal expected snowfall.

2. Avoid installing vent terminal above public walkways.

If this is not possible, install the terminal at least

seven (7') feet above the walkway.

3. Vent terminal should be at least four (4') feet to the

side of and at least one (1') foot above doors and

windows.

4. Vent terminal should be at least three (3') feet above

any forced air inlet located within ten (10') feet.

5. Vent terminal should be located at least six (6') feet

from the combustion air intake of another appliance.

6. Vent terminal should be located at least four (4') feet

above any electric or gas meters, regulators, and

relief equipment.

General Venting Requirements:

This furnace may be common vented only with other
Category I appliances. Common venting is allowed as
permitted by National and/or local codes. Refer to the
applicable sections of the (U.S.) National Fuel Gas Code
ANSI Z223.1/NFPA54, and/or CSA B149.1 Natural Gas
and Propane Installation Codes for proper sizing and set
up.

The vent must be terminated with a listed vent cap.
This venting must be installed in accordance with the vent
manufacturer's instructions and be in accordance with all
local codes and/or National Codes. Follow Figure 9 for
vent exit options.

The following requirements are provided for a proper
venting system:

1. Be sure that the chimney flue is clear of any dirt or

debris.

2. Be sure that the chimney is not servicing an open

fireplace.

3. Never reduce the pipe size below the outlet size of

the furnace without checking the applicable sections

of the (U.S.) National Fuel Gas Code ANSI

Z223.1/NFPA54, and/or CSA B149.1 Natural Gas and

Propane Installation Codes.

20571201 Issue 0527 Page 13 of 28

4. All pipe should be supported using the proper clamps
and/or straps. These supports should be at least
every four (4') feet.

5. All horizontal runs of pipe should have at least a 1/4"
(in.) per foot of upward slope from the furnace to the
vent terminal.

6. All runs of pipe should be as short as possible with
as few turns as possible.

7. Seams should be tightly joined and checked for
leaks.

8. The flue pipe must not extend into the chimney but
be flush with the inside wall.

9. The chimney or vent pipe must extend at least three
(3') feet above the highest point where it passes
through a roof of a building and at least two (2') feet
higher than any portion of a building within a
horizontal distance of ten (10') feet. It shall also
extend at least five (5') feet above highest connected
equipment flue collar.

Figure 9

VENT EXIT OPTIONS

3. Remove the four (4) screws that secure the
combustion blower adaptor plate to the flue collector
box, taking care to support the blower assembly so
that it does not fall.

4. Rotate the blower 90° (degrees) clockwise, so that
the outlet of the blower is pointing toward the right
side panel of the furnace.

5. Insure that the gasket is in place between the blower
adaptor plate and the flue collector box. Reattach the
blower assembly to the flue collector box, using the
four (4) screws removed in step 3. Be sure that the
screws are properly tightened and that the gasket
seals the plate to the box.

6. Reconnect the pressure switch tubing to the
combustion blower.

7. (Optional) Install vent pipe guard.
Kit Number 20284801.

Figure 10

VENT PIPE GUARD KIT

For Horizontal Positions:

It is not necessary to reposition any of the

components of the furnace in order to install it in either
horizontal position. As outlined above, it is permissible to
use the side vent exit for the horizontal-left position, if
desired.

10. The 3" to 4" vent adaptor coupling must be used to
connect to the combustion blower outlet. It must be
installed directly to the combustion blower outlet (See
Figure 8).

Checking For Vent Oversizing:

If this furnace is replacing a furnace that is attached
to a venting system serving other appliances, the venting
system is likely to be too large to properly vent all of the
attached appliances. An improperly sized venting system

To Convert to Side Flue Exit:

can lead to condensation, leakage, or spillage.

1. Remove the louver door from the furnace. (Be sure
the side vent exit knock-out is removed from the right
side panel of the cabinet. See Figure 9.)

2. Disconnect the pressure switch tubing from the
combustion blower.

20571201 Issue 0527 Page 14 of 28

CARBON MONOXIDE POISONING HAZARD

Failure to follow the steps outlined below for each appliance connected to the venting system being placed

into operation could result in carbon monoxide poisoning or death.

The following steps shall be followed for each appliance connected to the venting system being placed into

operation, while all other appliances connected to the venting system are not in operation:

1. Seal any unused openings in the venting system.

2. Inspect the venting system for proper size and horizontal pitch, as required in the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 or the CSA B149.1, Natural Gas and Propane Installation Codes and these
instructions. Determine that there is no blockage or restriction, leakage, corrosion and other deficiencies
which could cause an unsafe condition.

3. As far as practical, close all building doors and windows and all doors between the space in which the
appliance(s) connected to the venting system are located and other spaces of the building.

4. Close fireplace dampers.

5. Turn on clothes dryers and any appliance not connected to the venting system. Turn on any exhaust fans,
such as range hoods and bathroom exhausts, so they are operating at maximum speed. Do not operate
a summer exhaust fan.

6. Follow the lighting instructions. Place the appliance being inspected into operation. Adjust the thermostat
so appliance is operating continuously.

7. Test for spillage from draft hood equipped appliances at the draft hood relief opening after 5 minutes of main
burner operation. Use the flame of a match or candle.

8. If improper venting is observed during any of the above tests, the venting system must be corrected in
accordance with the National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CSA B149.1, Natural Gas and

Propane Installation Codes.

9. After it has been determined that each appliance connected to the venting system properly vents when
tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas-fired
burning appliance to their previous conditions of use.

ELECTRICAL CONNECTIONS

When installed, the furnace must be electrically
grounded in accordance with local codes or, in the
absence of local codes, with the (U.S.) National Electrical
Codes, ANSI/NFPA 70 or CSA Standard C22.1; Part 1
Canadian Electrical Code. For proper installation refer to
furnace rating label for electrical ratings and for the field
wiring of this unit refer to furnace wiring specifications on
page 5 or alternately from the wiring diagram on page 27.
In all instances, other than wiring for the thermostat, the
wiring to be done and any replacement of wire shall
conform with the temperature limitation for Type T wire
[63°F rise (35°C)].

The electrical connections and the thermostat
connections are made at the openings on either side
panel of the unit in the control box area. Either side may
be used as convenient, but the provided hole plugs must
be inserted in the unused holes.

The control system depends on the correct polarity of
the power supply. Connect "Hot" (H) wire and "Ground"
(G) wire as shown in furnace wiring specification on
wiring diagram. Use reference Table on page 3 (Furnace
Specifications), for over current protection, max unit amp

rating and wire size. Use copper wire only for 115V­supply service to unit. When replacing any original
internal wiring, use only 105°C, 16 AWG copper wire.

Thermostat:

Instructions for wiring the thermostat are packed in
the thermostat (field supplied) box. Make the thermostat
connections as shown in furnace wiring specifications at
the 24-volt terminal board located in the control box.

Single Stage Thermostat Operation:

The automatic heat staging option allows a single stage
thermostat to be used with a two stage furnace. To
activate this option, move the jumper pin (see Figure 11)
to desired setting (5 minutes or 10 minutes). The furnace
will start on first (1ST) stage heat and stay at first (1ST)
stage heat for the duration of the selected time before
switching to 2nd stage heat.

20571201 Issue 0527 Page 15 of 28

Figure 11

AUTOMATIC HEAT STAGING JUMPER

When installing optional accessories to this appliance,
follow the manufacturer's installation instructions included
with the accessory.

GAS CONNECTIONS

Gas piping shall be of such size and so installed as
to provide a supply of gas sufficient to meet maximum
demands without undue loss of pressure between the gas
meter and the furnace. It is recommended that the gas
line to the furnace shall be a separate line direct from the
meter, unless the existing gas line is of ample capacity.
Refer to gas pipe capacity table in the National Fuel Gas
Code ANSI Z223.1/NFPA54, and/or CSA B149.1 Natural
Gas and Propane Installation Codes.

If local codes allow the use of a flexible gas appliance
connector, always use a new listed connector. Do no use
a connector which has previously serviced another gas
appliance.

Use a joint compound (pipe dope) that is resistant to
the action of liquefied petroleum gases or any other
chemical constituents of the gases to be conducted
through the piping.

For proper furnace operation the maximum gas
supply pressure is 14" w.c. and the minimum gas
supply pressure is 4.5" w.c. - Natural (11" w.c. - LP)
as shown on rating label.

Before any system of gas piping is finally put into
service, it should be carefully tested to determine if it is
gas tight. Check all piping for leaks using soapy water
and a brush. The piping must stand a pressure of six (6)
inches of mercury (3 PSIG) for a period of ten (10)
minutes or as required by local authority.

The unit cabinet must have an uninterrupted or
unbroken electrical ground to minimize personal
injury if an electrical fault should occur. This may
consist of electrical wire or approved conduit when
installed in accordance with existing electrical
codes. Do not use gas piping as an electrical
ground. Failure to follow this warning can result in
an electrical shock, fire, bodily harm, or loss of life.

The furnace and its individual shutoff valve
must be disconnected from the supply piping
system during any pressure testing of that system
at test pressures in excess of 1/2 PSIG (3.5kPa or
14"w.c.).

The furnace must be isolated from the gas
supply piping system by closing its individual
manual shutoff valve during any pressure testing of
the gas supply piping system at pressures equal to
or less than 1/2 PSIG (3.5kPa or 14"w.c.). Failure
to follow the above procedures could lead to a
hazardous condition and bodily harm.

Figure 12-A

GAS CONTROL PIPING

FIRE OR EXPLOSION HAZARD

Failure to follow the safety warnings exactly

Figure 12-B

TYPICAL GAS SERVICE CONNECTION

could result in serious injury, death or property
damage.

Never test for gas leaks with an open flame.
Use a commercially available soap solution made
specifically for the detection of leaks to check all
connections. A fire or explosion may result causing
property damage, personal injury or loss of life.

20571201 Issue 0527 Page 16 of 28

This furnace is manufactured for use with Natural gas
and must be converted using the proper LP conversion kit
for use with LP (Propane) gas. For LP (Propane) gas, a
tank regulator is required to reduce supply pressure to
12"-13"w.c. For manifold pressure see Table 6.

A main manual shut off valve must be used in the
gas piping. The shut off type and location must follow
local codes and should always be in an accessible but
protected location. In the absence of local codes the
recommended methods for installing the gas piping to the
furnace are shown in Figures 12-A and 12-B.

The gas valve contains two threaded ports for a 1/8"
NPT tap in order to test incoming gas pressure and
outgoing manifold pressure (See Figure 13).

CONTROL BOARD & VARIABLE SPEED MOTOR FEATURES

Humidifier Connections:

Terminals are provided on the blower control board
for connections to a 120-volt optional humidifier. The
"HUM" terminal is energized whenever the thermostat
calls for heat. Refer to furnace wiring diagram for specific
connection information.

Many soaps used for leak testing are corrosive to
certain metals. Piping must be rinsed thoroughly
with clean water after leak check has been
completed.

Never use an open flame when testing for gas
leaks! Use of an open flame could lead to a fire or
explosion.

setup, the variable speed motor will operate at a 10%
reduction in the normal cooling airflow rate when there is
a call for dehumidification.

Both dehumidification methods described above can

be utilized on the same furnace.

Electronic Air Cleaner Connections:

Terminals are provided on the blower control board
for connection of a 120-volt optional electronic air cleaner.
The "EAC" terminal is energized whenever the thermostat
calls for heat, cooling, or continuous blower. Refer to the
furnace wiring diagram for specific connection information.

Continuous Blower Operation:

The comfort level of the living space can be
enhanced when using this feature by allowing continuous
circulation of air between calls for cooling or heating. The
circulation of air occurs at half the full cooling airflow rate.

To engage the continuous blower operation, place the
fan switch on the thermostat into the ON position. A call
for fan from the thermostat closes R to G on the ignition
control board. The control waits for a 1 second
thermostat debounce delay before responding to the call
for fan by ramping the circulating blower up to 50% of the
cooling speed, but not less than 425 cfm's. When the call
for continuous fan is satisfied, the control immediately de­energizes the circulating blower.

Dehumidification:

For situations where humidity control is a problem, a
dehumidification feature has been built into the variable
speed motor. At the start of each cooling cycle, the
variable speed motor will run at 82% of the rated airflow
for 7.5 minutes. After 7.5 minutes has elapsed, the motor
will increase to 100% of the rated airflow.

Additional dehumidification can be achieved by
connecting a humidistat to the DEHUM and R terminals
on the integrated ignition/blower control board. In this

Variable Speed Features:

The furnace is equipped with a variable speed
circulation air blower motor that will deliver a constant
airflow within a wide range of external static pressures.

Other features of this variable speed motor include:

Soft Start:

The variable speed motor will slowly ramp up to
normal operating speed. This minimizes noise and
increases comfort by eliminating the initial blasts of air
encountered with standard motors.

Soft Stop:

At the end of a cooling or heating cycle, the variable
speed motor will slowly ramp down after a short blower
"off" delay. If continuous blower operation has been
selected, the variable speed motor will slowly ramp down
until it reaches the airflow for that mode.

Circulating Airflow Adjustments

Heating Mode:

The unit, as shipped, is factory set (setting "A") to run
at the middle of the heating rise range as shown on the
unit rating plate. Adjustments can be made to the heating
airflow by repositioning the jumper plug marked HEAT-A,
B, C, D (see AirFlow Adjustment Table on page 4) based
on the information found in the table. Heating rise must

always be within the rise range shown on the rating
plate.

20571201 Issue 0527 Page 17 of 28

Cooling Mode:

The units are factory set for the highest airflow for
each model. Adjustments can be made to the cooling
airflow by repositioning the jumper plug marked COOL ­A, B, C, D (see AirFlow Adjustment Table on page 4)
based on the information found in the table.

By moving the ADJUST jumper plug (see Table on
page 4) from the NORM position to the (+) or (-) position
will also cause the cooling airflow setting to be raised or
lowered by 15%.

The TEST position on the ADJUST tap is not used.

UNIT SEQUENCE OF OPERATION

To determine what CFM the motor is delivering at any
time, count the number of times the amber LED on the
control board flashes. Each flash signifies 100 CFM;
count the flashes and multiply by 100 to determine the
actual CFM delivered (for example: 10 flashes x 100 =
1000 CFM).

Here's How Your Heating System Works:

Standby Mode

When the control is in standby mode, it continually
monitors thermostat input, rollout switch, and flame
sense.

Call For Heat

On a call for 1st stage heat (W1) from the room
thermostat, the ignition control performs a 1-second self­check. The control verifies the limit switch is closed and
both low and high pressure switches are open. The
control always starts on low-fire and ignores 2nd stage call
for heat until low heat is established and heat blower on
delay is complete. The induced draft blower is energized
to high speed and waits for the low pressure switch to
close before starting a 15-second pre-purge period. Upon
completion of the pre-purge the hot surface igniter is
energized for a period of 7 seconds (15 seconds on
retries) before the gas valve is energized on 1st stage and
main burners ignite. The induced draft blower remains on
high speed with the gas on low fire for the first 15
seconds of steady heat and ignores any 2nd stage
demand. After the 15 second period the control switches
the inducer to low speed. After a 30 seconds blower "on"
delay, the control energizes the low heat circulating air
blower. The blower runs at reduced CFM (approximately
400 CFM) for 30 seconds then ramps up to 1st stage heat
speed.

If 1st stage heating operation is not sufficient to satisfy
the heating demand, the room thermostat initiates a call
for 2nd stage heat (W1 and W2). The control changes the
inducer from low to high speed and confirms the high-fire
pressure switch contacts are closed and the gas valve
energizes on 2nd stage heat. The circulating air blower
then ramps up to 2nd stage heat speed.

When the 2nd stage call for heat is satisfied, the
control shuts off the gas valve and runs the combustion
air blower for a post purge period of 5 seconds. The
circulating air blower continues to run for approximately 3
minutes before ramping down. If the thermostat W2 call
ends and W1 remains, the control de-energizes the high
gas output, changes the inducer speed from high to low
and the gas valve drops back to 1st stage heat. After
approximately 2 minutes the circulating air blower ramps
down to 1st stage heat speed.

In the event the unit loses ignition, the control will
attempt to recycle up to five times before it goes into a 1­hour lockout. Lockout may be manually reset by
removing power from the control for more than 1 second
or removing the thermostat call for heat for more than 3
seconds.

If during a heating cycle the limit control senses an
abnormally high temperature and opens, the ignition
control de-energizes the gas valve and the combustion
blower while the circulating blower ramps up to 2nd stage
heat speed. The circulating blower remains energized
until the limits are closed.

Should overheating occur, or the gas supply fail to
shut OFF, turn OFF the manual gas valve to the
appliance BEFORE turning OFF the electrical
supply. A failure to adhere to this warning can
result in a fire or explosion and bodily harm.

Fan "ON"

A call for continuous fan from the thermostat closes
R to G on the control board. The control waits for a 1­second debounce delay before responding by energizing
the circulating air blower at 50% of the cooling speed.
When the call for fan is turned off, the control de­energizes the circulating blower.

Cooling

A call for cooling from the thermostat closes R to Y
and R to G on the blower control board. The control
waits for a 1-second thermostat debounce delay before
energizing the circulating air blower to 82% of the cooling
speed. After 7.5 minutes, the circulating blower
automatically ramps up to 100% of the cooling speed.
When a call for cooling is satisfied, the circulating blower
ramps back down to 82% of the cooling speed for 60
seconds then shuts off.

20571201 Issue 0527 Page 18 of 28

STARTUP AND OPERATIONAL CHECKOUT

It is not recommended that this furnace be used as
a construction heater during any phase of
construction. Very low return air temperatures,
harmful vapors and operation of the unit with
clogged or misplaced filters will damage the unit.
The unit may only be used for heating of buildings
or structures under construction, if the conditions
listed on page 6 in the "Introduction" section of
these instructions are met.

The automatic gas valve controls the flow of gas to
the main burners. The control circuit built into the
automatic valve body has 2 positions: "OFF" and "ON"
(Figure 13). To shut off gas manually: Switch from "ON"
to "OFF" position. When in "OFF" position, the main
burners are extinguished.

This furnace is equipped with an automatic hot­surface ignition control and does not require the manual
lighting for furnace operation.

1. Be sure all electrical power is OFF.

2. Check all wiring using proper wiring diagram on
inside of the control box cover.

3. Turn ON the electrical power.

4. Set the ignition system control switch in the "ON"
position.

5. Set the thermostat above room temperature.

6. The hot-surface ignitor will heat-up to an "orange"
glow, the main burners will ignite.

Figure 14

TYPICAL FLAME APPEARANCE

(Main Burners)

Figure 13

GAS CONTROL DIAGRAM

Do not attempt to manually light the burners.
Failure to follow this warning can lead to electrical
shock that could result in bodily harm.

7. Recheck for leaks in the manual shut off valve, gas
control valve and gas connections using a soap
solution.

Never use an open flame when testing for gas
leaks! Use of an open flame could lead to a fire or
explosion.

Many soaps used for leak testing are corrosive to
certain metals. Piping must be rinsed thoroughly
with clean water after leak check has been
completed.

Manifold Pressure Adjustment:

Turn OFF the gas and electrical before

After the ductwork connections have been made, gas
piping and electrical wiring completed and the furnace
has been properly vented, the unit should be started and
adjusted for proper operation. Check off the following

preceeding! Remove the manifold pressure tap pipe

plug from the gas valve (Figure 13 outlet pressure tap)
and install a pressure tap and connect it to a manometer.
Turn on the gas and electrical supplies.

steps as they are completed.

20571201 Issue 0527 Page 19 of 28

The gas control (Figure 13) has two separate
pressure regulator adjustment screws, one for 1st stage
(marked "LO") and the second one for 2nd stage (marked
"HI"). The adjusting screws are positioned on either

side of the barbed fitting. The pressure regulator
adjustment is sensitive: one turn of the adjusting
screw will result in a relatively large change in
manifold pressure. Turn regulator-adjusting screws
IN (clockwise) to increase pressure, OUT
(counterclockwise) to decrease presure.

Set the unit on high fire and adjust the 2nd stage high
fire pressure regulator to the required setting. Disconnect
the violet wire from the "HI" terminal on the gas control
and the burners will drop down to the 1st stage low fire,
then adjust the 1st stage pressure regulator setting as
required. Gas input must never exceed the value shown
on the furnace rating label. These units are equipped for
rated input at manifold pressures of 2.3" w.c. (1st stage)
and 3.5" w.c. (2nd stage) for natural gas. When these
furnaces have been converted for use with LP (propane)
gas, the manifold pressures are 6.4" w.c. (1st stage) and

10.0" w.c. (2nd stage). After proper adjustments,
reconnect violet wire and furnace should go up to 2
stage high fire. Turn OFF gas, replace manifold pressure
tap pipe plug, regulator adjustment vent cap, and turn ON
gas.

At higher altitudes and varying heating valves,
manifold pressure or orifice changes maybe
required. Consult Tables 7 and 8 for appropriate
values. Failure to follow this warning could lead to
a hazardous furnace operating condition and result
in serious bodily injury or loss of life.

TABLE 5

Gas Rate (Cubic Feet per Hour)

TEST DIAL

Seconds for

One

Revolution

10 160 360 720
12 150 300 600
14 129 257 514
16 113 225 450
18 100 200 400
20 90 180 360
22 82 164 325
24 75 150 300
26 69 138 276
28 64 129 258
30 60 120 240
32 56 113 226
34 53 106 212

1/2

Cubic

Feet

Cubic

1

Foot

2

Cubic

Feet

Seconds for

One

Revolution

36 50 100 200
38 47 95 190
40 45 90 180
42 43 86 172
44 41 82 164
46 39 78 156
48 37 75 150
50 36 72 144
52 35 69 138
54 34 67 134
56 32 64 128
58 31 62 124
60 30 60 120

1/2

Cubic

Feet

TEST DIAL

1

Cubic

Foot

2

Cubic

Feet

4. Calculate the furnace input using the following
formula:

nd

BTUH = Cubic Ft/Hr x BTU/Cubic Foot

The local gas supplier should be able to provide the
heating value of the gas, in BTU/cubic foot. If a
specific value is not available, use 1000 BTU/cubic
foot for Natural gas or 2500 BTU/cubic foot for
Propane (LP).

Furnace input should be maintained within ± 2% of
the value on the rating plate or appropriate altitude
derate. Adjust manifold pressure or change
orifices size if required.

Determining Furnace Input - Natural Gas Only

NOTE: All access doors must be in place when checking

gas input.

1. Turn OFF all other gas appliances (except for pilot
burners) served by the same gas meter.

5. Calculate the unit's actual input rate.

Example: If the heating value of the natural gas is 1015

Btu/cu. and it takes 60 seconds to burn 2 cu.
ft. of gas then:

Input = 1015 Btu/cu. ft. X 1 rev X 2 cu. ft./rev. X 3600

60 sec.

2. With furnace operating in full heat cycle, note how
many seconds it takes for one full revolution of the

Input = 121,800 Btu/hr.

smallest dial on the meter. Typically, this will be a
1/2 - or - 1 - cubic foot test dial.

3. Using the number of seconds for one revolution and
the size of the meter dial, determine the cubic foot
per hour of gas flow by using the formula provided
below or Table 5.

Cubic Ft/Hr =

20571201 Issue 0527 Page 20 of 28

Number of Dial Revolutions x Cubic Foot/Revolution x 3600
Time (in seconds) Required for Number of Timed Revolutions

Burner Orifice Sizing:

The furnace is supplied with standard orifices for the

gas shown on the rating plate. Table 6 shows
combinations of heating values and specific gravities for
various gases, from which proper input can be obtained.

If changing orifices is required, remove the manifold

from the furnace (following the instructions found on page

24) and replace orifices as required by Table 6, the

altitude derating section of this instruction or as local code
dictates.

TABLE 6

Burner Orifice Selection

Type of Gas@Manifold Press.

(Heating Value-Specific Gravity)

Btu per Cu. Ft.

Orifice

Size

(Drill #)

Natural Manifold Press.= 3.5"w.c.

800-0.6

900-0.6
1000-0.6
1100-0.6

40
41
42
43

Propane Manifold Press.= 10"w.c.

2500-1.53

54

After securing the manifold assembly, replace all
other components and/or wiring, being sure that all
connections and screws are tightened properly.

Altitude Derating:

The following information is provided as guidelines for
altitude derating and is not meant to supersede any state
or local codes. Local codes have priority over any others
and in some case might limit your options in dealing with
an altitude derate situation.

NOTE: In Canada for altitudes up to 4500 ft. (1372 m)

see the rating label on this furnace for proper
manifold pressure and orifice size. Certification
for installations at altitudes over 4500 ft. (1372 m)
is the jurisdiction of local authorities.

TABLE 7

High Altitude Manifold Pressure Derate

(with standard 42 orifice Natural / 54 orifice LP sizes)

Altitude

(Feet)

0-999 4.32 3.88 3.50 3.16 2.84 10
1000-1999 4.32 3.88 3.50 3.16 2.84 10
2000-2999 3.67 3.29 2.97 2.68 2.41 8.46
3000-3999 3.38 3.04 2.74 2.47 2.22 7.74
4000-4999 3.11 2.79 2.52 2.27 2.04 7.05

* Heating-Value based on atmospheric pressure of 30 inhg and 60°F temperature.

*Heating Value of Natural Gas

(BTU/FT3)

900 950 1000 1050 1100 2500

LP

Propane

If local codes require an orifices change the
appropriate orifice size based on the elevation and the
heating value can be found in Table 8. Sizing of the
orifice must be based on the previously mentioned 4%
derate for each 1,000 feet for installations at/or above
2,000 feet rule and the orifices must be drilled in such a
way as to assure concentricity. Hand drilling of orifices

is unacceptable.

TABLE 8

High Altitude Orifice Size Derate

Altitude

(Feet)

2000-2999 N.C. N.C. 43 43 44 N.C.
3000-3999 N.C. N.C. 43 44 44 N.C.
4000-4999 43 43 44 44 45 55

* Heating-Value based on atmospheric pressure of 30 inhg and 60°F temperature.

*Heating Value of Natural Gas

(BTU/FT3)

900 950 1000 1050 1100 2500

LP

Propane

Hand drilling of orifices is never acceptable since it
could lead to delayed ignition, overfiring, improper
combustion, flashback and flame rollout. All these
conditions could lead to a fire hazard and bodily
harm, or loss of life.

Check with your local gas company to find out if the
gas supply in your area is derated. Gas deration negates
the necessity of performing any adjustment on the
furnace.

If your gas supply is not derated, regardless of the
type of gas used, installation of this furnace at elevations
above 2,000 ft. requires an input reduction at the rate of
four percent (4%) for each 1,000 ft. above sea level.

Unless an orifice change is specified by an applicable
code, the recommended method of altitude derating this
furnace is to appropriately lower your manifold pressure.
The appropriate manifold pressures based on the
elevation and the heating value can be found in Table 7.

Blower Adjustment Checkout:

This furnace is equipped with a variable speed
circulation air blower motor that will deliver a constant
airlfow within a wide range of external static pressures.
The unit as shipped is factory set to run at the middle of
the heating rise range as shown on the unit rating plate.

For low heat to high heat transition the control
changes the blower speed from low heat speed to high
heat speed. Check the temperature rise between the
return and supply plenums to make sure it is within the
rise range shown on the rating plate.

Heat blower off delay is a fixed 180 second delay.
After the 180 second delay the motor will slowly ramp
down to a soft stop. N0 adjustments need to be made in
the heating mode.

20571201 Issue 0527 Page 21 of 28

Limit Control Checkout:

After the furnace has been in operation for at least 15
minutes, restrict the return air supply by blocking the
filters or closing the return registers and allow the furnace
to shut down on high limit. The main burners will shut
OFF and the main blower and combustion blower should
continue to run. Remove the restriction and the burners
should come back on in a few minutes.

Flame Rollout Switch:

This unit is equipped with two (2) manual reset flame­rollout switches that protects against improper venting of
the flue gases from the heat exchanger due to blockage
causing heat (or flames) to "rollout" into the burner box
from the heat exchangers, either safety device will
activate and shut off power to the automatic gas valve
before there is damage to the furnace. The loss of power
to the gas valve will shut off the gas burners. Should this
occur, it will be necessary to determine the cause of the
rollout, correct the condition that caused it, and reset the
flame-rollout switch.

Pressure Switch Check:

To check the operation of the pressure switch vent
safety control, remove the vent adaptor from the
combustion blower. Place the furnace into operation for
high fire. Gradually cover up the blower outlet; the
furnace should first drop to low fire and with further
restriction of the opening, the main burners should shut
OFF. Remove the restriction and the unit should relight.
Replace the vent adaptor and reseal the opened joints as
required.

The operational checkout is now complete. Be sure
to adjust the thermostat to the desired setting and inform
the homeowner how to operate the furnace system before
leaving the job site.

If the pressure switch activates to shut the furnace
down, the vent system must be checked and
cleared. Failure to do so may result in serious
bodily harm or nuisance furnace shutdown and/or
a hazardous condition that may lead to property
damage, personal injury or death.

The furnace should be allowed to cool-off before
attempting to reset the switch. Failure to follow
these instructions could result in injury due to burns!

The switches are located behind the front access
door. Remove front access door from the furnace and
reset by pushing in the button in the middle of the switch
(between the two wire connections - See Figure 16).
Very little force is required to push the reset button, and
a "click" should be heard when the switch resets.

Figure 16

FLAME ROLLOUT SWITCH

20571201 Issue 0527 Page 22 of 28

SEQUENCE OF OPERATION

DIRECT IGNITION SYSTEM CONTROL

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SERVICING THE FURNACE

ELECTRICAL SHOCK, FIRE OR EXPLOSION
HAZARD

Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.

Improper servicing could result in dangerous
operation, serious injury, death or property damage.

• Before servicing, disconnect all electrical
power to furnace.

• Wehn servicing controls, label all wires
prior to disconnecting. Reconnect wires
correctly.

• Verify proper operation after servicing.

The ability to properly perform maintenance on this
equipment requires certain mechanical skills and
tools. If you are at all uncertain, contact your
dealer for qualified maintenance and service since
improper service could lead to furnace shutdown or
a hazardous condition which could lead to an
unsafe condition and bodily harm.

Combustion Component Check:

The heat exchanger, gas burners and venting system
must be checked each year, prior to the heating season,
by a qualified dealer/serviceman.

The following procedures should be performed:

1. Remove the burner/manifold assembly from the

furnace, follow the instructions found on this page.

2. Place the burner/manifold assembly on a flat work

area and vacuum the burners. It might be necessary

to use a soft bristly brush to remove dirt and then

vacuum.

3. Disconnect wiring to combustion blower.

4. Disconnect wiring to pressure switches, and remove

pressure switches.

5. Remove the burner opening inlet plate and the flue

collector box with the combustion blower attached.

This will expose both the burner and flue openings of

the primary heat exchangers.

6. Vacuum the length of each heat exchanger tube

using a straight attachment into the burner openings

and the flue openings.

7. Replace the flue collector box, burner opening inlet

plate, and burner/manifold assembly. Insure that all

gaskets are properly positioned and that no leaks

exist.

8. Reattach all wiring and piping as per the wiring
diagram and installation instructions.

9. Turn on utilities and check for leaks using soapy
water and a brush.

10. A visual check of the main burner should be made at
the beginning of each heating season.

11. Check the input rate and adjust if necessary.

12. Perform a safety check of the limit control and
pressure switch.

13. Check the air filter, clean and/or replace as
necessary.

14. Replace the appropriate access panels or door.

Never use an open flame when testing for gas
leaks! Use of an open flame could lead to a fire or
explosion!

Many soaps used for leak testing are corrosive to
certain metals. Piping must be rinsed thoroughly
with clean water after leak check has been
completed.

Manifold (or Burner/Manifold) Removal/Replacement:

1. Make sure that all utilities (gas and electricity) are
turned off upstream of the furnace.

2. Remove the louvered access door by sliding the door
straight up, swinging the bottom of the door away
from the furnace, and pulling the door down and out
of the furnace (See Figure 17).

3. Disconnect the gas line from the gas valve. Be sure
that a wiring diagram is available, or be ready to
mark any wires that are disconnected. Unplug the
three connectors from the gas valve.

Figure 17

FURNACE PANEL REMOVAL

20571201 Issue 0527 Page 24 of 28

4. Disconnect wires from rollout switch.

5. Remove manifold or burner/manifold assembly.

Manifold ONLY
a. Remove the No. 10 screws that secure the

manifold pipe to both legs of the manifold
assembly. The manifold pipe must be

supported during this step, or it could fall and
damage the furnace or cause bodily injury!

b. Slide the manifold pipe (with valve and orifice)

forward, out of the furnace.

Burner/Manifold Assembly
a. Remove the No. 10 screws that secure the

burner/manifold assembly legs to the furnace.

The manifold pipe must be supported during
this step, or it could fall and damage the
furnace or cause bodily injury!

b. Slide the burner/manifold assembly forward, out

of the furnace until the assembly is clear of the
manifold retention pins.

c. Rotate the assembly slightly, in order for the legs

to clear the sides of the cabinet, and remove
through the front of the furnace.

8. To reinstall the manifold pipe or burner/manifold
assembly, reverse the above steps.

Replacement

1. Place the blower in the blower opening of the unit
and reconnect the auxiliary limit leads.

2. Slide the blower back, into the unit, taking care to
clear the control box mounting tabs.

3. When the blower is about halfway into the cabinet,
rotate the rear of the blower UP so that the rear of
the blower legs engage the side rails in the blower
partition.

4. Continue sliding the blower into the unit until the front
of the blower housing is behind the control box
mounting tabs. Rotate the front of the blower UP
until the legs lie flat against the bottom of the blower
partition, then slide blower fully into position. The
rear of the blower should be against the stop in the
partition and the rear of the blower legs should be
under the partition.

5. Reattach the two (2) blower securing screws, the
control box, any disconnected wiring, the blower
access panel, and the control box access panel.

Lubricating Motors:

Direct drive motor and blower assemblies are factory

lubricated and normally do not require oiling. If oiling is
required lubrication of the blower motor is to be
preformed only by a qualified service agency.

Blower Removal/Replacement:

Removal

1. Turn OFF all electrical power to the furnace.

2. Remove the control box access panel and blower
access panel.

3. Unplug wires from the blower assembly to the control
box.

4. Remove the four (4) screws securing the control box
in the unit (two (2) in the cabinet at the sides of the
blower door opening and two (2) at the top rear of the
control box). Be sure to support the control box so
that it does not fall!

5. Rotate the control box out of the cabinet and support
it so that no strain is placed on any wiring. It may be
necessary to disconnect the electrical supply and
thermostat wiring from the control board.

6. Remove the blower retaining screws from the front of
each blower leg (See Figure 18). These are the two
(2) screws located in the blower compartment that
secure the blower legs to the blower partition panel.

7. Slide the blower forward about two (2) inches. This
will disengage the rear of the blower legs from the
blower partition. Rotate the front of the blower down
to clear the control box mounting tabs on the
underside of the blower partition, and continue sliding
the blower forward until it is out of the unit. Take
care to clear the control box mounting tabs. If
necessary, disconnect the auxiliary limit leads on the
sides of the blower housing.

Figure 18

BLOWER REMOVAL AND REPLACEMENT

20571201 Issue 0527 Page 25 of 28

TROUBLE SHOOTING With LED Indicator Assistance

Troubleshooting

Make the following visual checks before toubleshooting:

1. Check to see that the power to the furnace and the
integrated ignition/blower control board is ON.

2. The manual shutoff valves in the gas line to the
furnace must be open

3. Make sure all wiring connections are secure.

4. Review the Sequence of Operation (see page 23).

Start the system by setting thermostat above room
temperature. Observe system response. Then use the
information provided in this section to check the system
operation.

The furnace has a built-in, self-diagnostic capability. If a
system problem occurs, a fault code is shown by a red
LED on the control board. The control continuously
monitors its own operation and the operation of the
system. If a failure occurs, the LED will indicate the
failure code. The flash codes are presented in Table 9.

Table 9

Failure Codes - Red LED

LED

Status

LED Off

LED On Normal operation

1 Flash Flame present with gas valve off

2 Flashes Pressure switch closed with inducer off

3 Flashes Low-fire pressure, or IBS switch open

4 Flashes High limit switch or rollout switch open

5 Flashes Not used

6 Flashes Pressure switch cycle lockout

7 Flashes Lockout due to no ignition

8 Flashes Lockout due to too many flame dropouts

9 Flashes Incorrect polarity and phasing

No power to control or control hardware fault
detected

Fault Description

Fault Code History Button

The control stores the last five fault codes in memory. A
pushbutton switch (fault code history switch) is located on
the control (see Page 5). When the pushbutton switch is
pressed and released, the control flashes the stored fault
codes. The most recent fault code is flashed first; the
oldest fault code is flashed last. To clear the fault code
history, press and hold the pushbutton switch in for more
than 5 seconds before releasing.

High Heat State LED

On these models, a green LED is provided on the control
board to indicate high heat state (see Table 10).

CFM LED

An amber LED is provided on the control board to display
CFM. To determine what CFM the motor is delivering at
any time, count the number of times the amber LED
flashes. Each flash signifies 100 CFM; count the flashes
and multiply by 100 to determine the actual CFM
delivered (for example: 10 flashes x 100 = 1000 CFM).

Table 10

High Heat State - Green LED

LED

Status

LED Off No demand for high heat

LED On High heat demand, operating normally

LED Flashing

High heat demand, high pressure switch not
closed

Description

20571201 Issue 0527 Page 26 of 28

WIRING DIAGRAM

20571201 Issue 0527 Page 27 of 28

NOTES

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