Johnson Controls YM8M-YMLM-MP, TM8M-TMLM-MP, CM8M-CMLM-MP, LM8M-LMLM-MP User Manual

INSTALLATION MANUAL

RESIDENTIAL GAS FURNACE
WITH PSC MOTOR

MODELS:
TM8M/TMLM*MP, YM8M/YMLM*MP,
CM8M/CMLM*MP, LM8M/LMLM*MP

(80% Modulating Multi-position / Low NOx)

LIST OF SECTIONS

SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

DUCTWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

GAS PIPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

ELECTRICAL POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

TWINNING AND STAGING . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

VENT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

LIST OF FIGURES

Duct Attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Vertical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Coil Flange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Horizontal Right Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Horizontal Left Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

PC Series Upflow Coil Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Horizontal Left or Right application (Right Shown) . . . . . . . . . . . . . . 8

Combustible Floor Base Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Horizontal Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Typical Attic Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Typical Suspended Furnace / Crawl Space Installation . . . . . . . . . . . 9

Downflow Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Downflow Installation - Gas Valve Rotation . . . . . . . . . . . . . . . . . . . . 9

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Side Return Cutout Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Upflow/Downflow Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Horizontal Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Electrical Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

LIST OF TABLES

Unit Clearances to Combustibles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Coil Projection Dimensions - PC Series Coils . . . . . . . . . . . . . . . . . . 6

Cabinet and Duct Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Recommended Filter Sizes (High Velocity 600 FPM) . . . . . . . . . . . . 8

High Altitude Orifices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Ratings & Physical / Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . 10

Estimated Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

START-UP AND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . 20

SAFETY CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

NORMAL OPERATION AND DIAGNOSTICS . . . . . . . . . . . . . 25

REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . 27

REPLACEMENT PART CONTACT INFORMATION . . . . . . . . 27

WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Thermostat Chart - Single Stage Air Conditioner –

Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .14

Thermostat Chart - Two Stage Air Conditioner –

Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .15

Thermostat Chart - Two Stage Air Conditioner with Single Stage

Thermostat – Variable Speed or PSC Modulating Furnace . . . . . . .16

Thermostat Chart - Single Stage Heat Pump –

Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .17

Thermostat Chart - Single Stage Heat Pump –

Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .18

Thermostat Chart - Two Stage Heat Pump –

Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .19

Combustion Air Inducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Combustion Airflow Path Through The Furnace

Casing to the Burner Compartment . . . . . . . . . . . . . . . . . . . . . . . . .20

Outside and Ambient Combustion Air . . . . . . . . . . . . . . . . . . . . . . . .21

Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Furnace Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Unconfined Space Minimum Area in Square Inch . . . . . . . . . . . . . .19

Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Gas Rate (CU FT/HR) at Full Input . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Inlet Gas Pressure Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Nominal Manifold Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Cooling Airflow - A/C Capacity in Tons . . . . . . . . . . . . . . . . . . . . . . .24

EFFICIENCY
RATING
CERTIFIED

ISO 9001

Certified Quality

Management System

These high efficiency, compact units employ induced combustion, reli­able hot surface ignition and high heat transfer aluminized tubular heat
exchangers. The units are factory shipped for installation in upflow or
horizontal applications and may be converted for downflow applica­tions.
These furnaces are designed for residential installation in a basement,
closet, alcove, attic, recreation room or garage and are also ideal fo r
commercial applications. All units are factory assembled, wired and
tested to assure safe dependable and economical installation and oper­ation.
These units are Category I listed and may be common vented with
another gas appliance as allowed by the National Fuel Gas Code.

SECTION I: SAFETY

This is a safety alert symbol. When you see this symbol on
labels or in manuals, be alert to the potential for personal
injury.

Understand and pay particular attention to the signal words DANGER,

WARNING, or CAUTION.

DANGER indicates an imminently hazardous situation, which, if not
avoided, will result in death or serious injury

WARNING indicates a potentially hazardous situation, which, if not
avoided, could result in death or serious injury

CAUTION indicates a potentially hazardous situation, which, if not

avoided may result in m inor or moderate injury.
alert against unsafe practices and hazards involving only property dam­age.

Improper installation may create a condition where the operation of
the product could cause personal injury or property damage.

Improper installation, adjustment, alteration, service or mainte­nance can cause injury or property damage. Failure to carefully

read and follow all instructions in this manual can result in fur­nace malfunction, death, personal injury and/or property dam­age. Only a qualifie d contractor, installer or service agency should

install this product.

.

.

It is also used to

368261-UIM-A-0508

368261-UIM-A-0508

SPECIFIC SAFETY RULES AND PRECAUTIONS

1. Only Natural gas or Propane (LP) gas are approved for use with
this furnace.

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

3. A gas-fired furnace for installation in a residential garage must be
installed as specified in these instructions.

4. Provide adequate combustion and ventilation air to the furnace
space as specified in these instructions.

5. Combustion products must be discharged outdoors. Connect this
furnace to an approved vent system only, as specified in SEC­TION VII of these instructions.

6. Test for gas leaks as specified in these instructions.

FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly 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 detection of leaks to
check all connections. A fire or explosion may result causing prop­erty damage, personal injury or loss of life.

7. Always install the furnace to operate within the furnace’s intended
temperature rise range. Only connect the furnace to a duct system
which has an external static pressure within the allowable range,
as specified on the furnace rating plate.

8. 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.

9. It is permitted to use the furnace for heating of buildings or struc­tures under construction where the application and use must com­ply with all manufacturer’s installation instructions including:

• Proper vent installation;

• Furnace operating under thermostatic control;

• Return air duct sealed to the furnace;

• Air filters in place;

• Set furnace input rate and temperature rise per rating plate

marking;

• Means for providing outdoor air required for combustion;

• Return air temperature maintained between 55ºF (13ºC) and

80ºF (27ºC);

• The air filter must be replaced upon substantial completion of

the construction process;

• Clean furnace, duct work and components upon substantial

completion of the construction process, and verify furnace­operating conditions including ignition, input rate, temperature
rise and venting, according to the manufacturer’s instructions.

10. When installed in a Non-HUD-Approved Modular Home or building
constructed on-site, combustion air shall not be supplied from
occupied spaces.

11. The size of the unit should be based on an acceptable heat loss
calculation for the structure. ACCA, Manual J or other approved
methods may be used.

SAFETY REQUIREMENTS

This product must be installed in strict compliance with the installa­tion instructions and any applicable local, state, and national codes
including, but not limited to building, electrical, and mechanical
codes.

• Refer to the unit rating plate for the furnace model number, and
then see the dimensions page of this instruction for return air ple­num dimensions in Figure 14, "Dimensions". The plenum must be
installed according to the instructions.

• Provide clearances from combustible materials as listed under
Clearances to Combustibles.

• Provide clearances for servicing ensuring that service access is
allowed for both the burners and blower.

• These models ARE NOT
into a HUD Approved Modular Home
(Mobile) Home.

• This furnace is not approved for installation in trailers or recre­ational vehicles.

• Furnaces for installation on combustible flooring shall not be
installed directly on carpeting, tile or other combustible material
other than wood flooring.

• Check the rating plate and power supply to be sure that the elec­trical characteristics match. All models use nominal 115 VAC, 1
Phase, 60-Hertz power supply. DO NOT CONNECT THIS APPLI­ANCE TO A 50 HZ POWER SUPPLY OR A VOLTAGE ABOVE
130 VOLTS.

• Furnace shall be installed so the electrical components are pro­tected from water.

• Installing and servicing heating equipment can be hazardous due
to the electrical components and the gas fired components. Only
trained and qualified personnel should install, repair, or service
gas heating equipment. Untrained service personnel can perform
basic maintenance functions such as cleaning and replacing the
air filters. When working on heating equipment, observe precau­tions in the manuals and on the labels attached to the unit and
other safety precautions that may apply.

CSA listed or approved for installation

or a Manufactured

COMBUSTION AIR QUALITY
(LIST OF CONTAMINANTS)

The furnace requires OUTDOOR AIR for combustion when the furnace
is located in any of the following environments.

• Restricted Environments

• Commercial buildings

• Buildings with indoor pools

• Furnaces installed in laundry rooms

• Furnaces installed in hobby or craft rooms

• Furnaces installed near chemical storage areas

• Chemical exposure

The furnace requires OUTDOOR AIR for combustion when the furnace
is located in an area where the furnace is being exposed to the follow­ing substances and / or chemicals.

• Permanent wave solutions

• Chlorinated waxes and cleaners

• Chlorine based swimming pool chemicals

• Water softening chemicals

• De-icing salts or chemicals

• 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

When outdoor air is used for combustion, the combustion air intake duct
system termination must be located external to the building and in an
area where there will be no exposure to the substances listed above.

2 Johnson Controls Unitary Products

The furnace area must not be used as a broom closet or for any
other storage purposes, as a fire hazard may be created. Never
store items such as the following on, near or in contact with the fur­nace.

1. Spray or aerosol cans, rags, brooms, dust mops, vacuum
cleaners or other cleaning tools.

2. Soap powders, bleaches, waxes or other cleaning com­pounds; plastic items or containers; gasoline, kerosene, ciga­rette lighter fluid, dry cleaning fluids or other volatile fluid.

3. Paint thinners and other painting compounds.

4. Paper bags, boxes or other paper products

Never operate the furnace with the blower door removed. To
do so could result in serious personal injury and/or equipment
damage.

CODES AND STANDARDS

Follow all national, local codes and standards in addition to this installa­tion manual. The installation must comply with regulations of the serv­ing gas supplier, local building, heating, plumbing, and other codes. In
absence of local codes, the installation must comply with the national
codes listed below and all authorities having jurisdiction.

In the United States and Canada, follow all codes and standards for the
following, using the latest edition available:

STEP 1 -Safety

• US: National Fuel Gas Code (NFGC) NFPA 54/ANSI Z223.1 and
the Installation Standards, Warm Air Heating and Air Conditioning
Systems ANSI/NFPA 90B

• CANADA: CAN/CGA-B149.1 National Standard of Canada. Natu­ral Gas and Propane Installation Codes (NSCNGPIC)

STEP 2 -General Installation

• US: Current edition of the NFGC and NFPA 90B. For copies, con­tact the

National Fire Protection Association Inc.
Batterymarch Park
Quincy, MA 02269

or for only the NFGC, contact the

American Gas Association,
400 N. Capital, N.W.
Washington DC 20001

or www.NFPA.org

• CANADA: NSCNGPIC. For a copy contact:

Standard Sales, CSA International
178 Rexdale Boulevard
Etobicoke, (Toronto) Ontario Canada M9W 1RS

STEP 3 -Combustion and Ventilation Air

• US: Section 5.3 of the NFGC, air for Combustion and Ventilation

• CANADA: Part 7 of NSCNGPIC, Venting Systems and Air Supply
for Appliances

STEP 4 -Duct Systems

• US and CANADA: Air Conditioning Contractors Association
(ACCA) Manual D, Sheet Metal and Air Conditioning Contractors
Association National Association (SMACNA), or American Soci­ety of Heating, Refrigeration, and Air Conditioning Engineers
(ASHRAE) 1997 Fundamentals Handbook Chapter 32.

STEP 5 -Acoustical Lining and Fibrous Glass Duct

• US and CANADA: Current edition of SMACNA and NFPA 90B as
tested by UL Standard 181 for Class I Rigid Air Ducts

STEP 6 -Gas Piping and Gas Pipe Pressure Testing

• US: NFGC; chapters 2, 3, 4, & 9 and National Plumbing Codes

• CANADA: NSCNGPIC Part 5

STEP 7 -Electrical Connections

• US: National Electrical Code (NEC) ANSI/NFPA 70

• CANADA: Canadian Electrical Code CSA C22.1

368261-UIM-A-0508

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 who have not kept up with changing residential and non-HUD
modular home construction practices. These instructions are required
as a minimum for a safe installation.

FOR FURNACES INSTALLED IN THE COMMON­WEALTH OF MASSACHUSETTS ONLY

For all side wall horizontally vented gas fueled equipment installed in
every dwelling, building or structure used in whole or in part for resi­dential purposes, including those owned or operated by the Com­monwealth and where the side wall exhaust vent termination is less
than seven (7) feet above finished grade in the area of the venting,
including but not limited to decks and porches, the following require­ments shall be satisfied:

1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At
the time of installation of the side wall horizontal vented gas
fueled equipment, the installing plumber or gasfitter shall
observe that a hard wired carbon monoxide detector with an
alarm and battery back-up is installed on the floor level where
the gas equipment is to be installed. In addition, the installing
plumber or gasfitter shall observe that a battery operated or
hard wired carbon monoxide detector with an alarm is installed
on each additional level of the dwelling, building or structure
served by the side wall horizontal vented gas fueled equipment.
It shall be the responsibility of the property owner to secure the
services of qualified licensed professionals for the installation of
hard wired carbon monoxide detectors

a. In the event that the side wall horizontally vented gas

fueled equipment is installed in a crawl space or an attic,
the hard wired carbon monoxide detector with alarm and
battery back-up may be installed on the next adjacent floor
level.

b. In the event that the requirements of this subdivision can

not be met at the time of completion of installation, the
owner shall have a period of thirty (30) days to comply with
the above requirements; provided, however, that during
said thirty (30) day period, a battery operated carbon mon­oxide detector with an alarm shall be installed.

2. APPROVED CARBON MONOXIDE DETECTORS. Each car­bon monoxide detector as required in accordance with the
above provisions shall comply with NFPA 720 and be ANSI/UL
2034 listed and IAS certified.

3. SIGNAGE. A metal or plastic identification plate shall be perma­nently mounted to the exterior of the building at a minimum
height of eight (8) feet above grade directly in line with the
exhaust vent terminal for the horizontally vented gas fueled
heating appliance or equipment. The sign shall read, in print
size no less than one-half (1/2) inch in size, "GAS VENT

DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUC­TIONS".

4. INSPECTION. The state or lo cal gas inspector of the side wall
horizontally vented gas fueled equipment shall not approve the
installation unless, upon inspection, the inspector observes car­bon monoxide detectors and signage installed in accordance
with the provisions of 248 CMR 5.08(2)(a)1 through 4.

INSPECTION

As soon as a unit is received, it should be inspected for possib le dam­age during transit. If damage is evident, the extent of the damage
should be noted on the carrier’s freight bill. A separate request for
inspection by the carrier’s agent should be made in writing. Also, before
installation, the unit should be checked for screws or bolts which may
have loosened in transit. There are no shipping or spacer brackets
which need to be removed from the interior of this unit.

Johnson Controls Unitary Products 3

368261-UIM-A-0508

FURNACE LOCATION AND CLEARANCES

The furnace shall be located using the following guidelines:

1. Where a minimum amount of air intake/vent piping and elbows will
be required.

2. As centralized with the air distribution as possible.

3. Where adequate combustion air will be available.

4. Where it will not interfere with proper air circulation in the confined
space.

5. Where the outdoor vent terminal will not be blocked or restricted.
Refer to “VENT CLEARANCES” located in SECTION VII of these
instructions. These minimum clearances must be maintained in
the installation.

6. Where the unit will be installed in a level position with no more than
1/4” (6.4 mm) slope side-to-side and front-to-back.

Installation in freezing temperatures:

1. Furnace shall be installed in an area where ventilation facilities
provide for safe limits of ambient temperature under normal oper­ating conditions.

Table 1: Unit Clearances to Combustibles (All Dimensions in Inches, and All Surfaces Identified with the Unit in an Upflow Configuration)

Application

Upflow B-Vent 1 (2.5) 3 (7.6) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) Combustible Yes Yes Yes No
Downflow B-Vent 1 (2.5) 3 (7.6) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5)
Horizontal B-Vent 1 (2.5) 3 (7.6) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) Combustible No Yes Yes

1.Special floor base or air conditioning coil required for use on combustible floor.

2.Line contact only permitted between lines formed by the intersection of the rear panel and side panel (top in horizontal position) of the furnace jacket and building
joists, studs or framing.

Top Front Rear Left Side Right Side Flue

In. (cm) In. (cm) In. (cm) In. (cm) In. (cm) In. (cm)

SECTION II: DUCTWORK

DUCTWORK GENERAL INFORMATION

The duct system’s design and installation must:

1. Handle an air volume appropriate for the served space and within
the operating parameters of the furnace specifications.

2. Be installed in accordance of National Fire Protection Association
as outlined in NFPA standard 90B (latest editions) or applicable
national, provincial, state, and local fire and safety codes.

3. Create a closed duct system. For residential and Non-HUD Modu­lar Home installations, when a furnace is installed so that the sup­ply ducts carry air circulated by the furnace to areas outside the
space containing the furnace, the return air shall also be handled
by a duct(s) sealed to the furnace casing and terminating outside
the space containing the furnace.

4. Complete a path for heated or cooled air to circulate through the
air conditioning and heating equipment and to and from the condi­tioned space.

The cooling coil must be installed in the supply air duct, down­stream of the furnace. Cooled air may not be passed over the heat
exchanger.

When the furnace is used with a cooling coil, the coil must be installed
parallel with, or in the supply air side of the furnace to avoid condensa­tion in the primary heat exchanger. When a parallel flow arrangement is
used, dampers or other means used to control airflow must be ade­quate to prevent chilled air from entering the furnace. If manually oper­ated, the damper must be equipped with means to prevent the furnace
or the air conditioner from operating unless the damper is in full heat or
cool position.

2. Do not allow return air temperature to be below 55º F (13° C) for
extended periods. To do so may cause condensation to occur in
the main heat exchanger, leading to premature heat exchanger
failure.

Clearances for access/service:

Ample clearances should be provided to permit easy access to the unit.
The following minimum clearances are recommended:

1. Twenty-four (24) inches (61 cm) between the front of the furnace
and an adjacent wall or another appliance, when access is
required for servicing and cleaning.

2. Eighteen (18) inches (46 cm) at the side where access is required
for passage to the front when servicing or for inspection or replace­ment of flue/vent connections.

In all cases, accessibility clearances shall take precedence over clear­ances for combustible materials where accessibility clearances are
greater.

Installation in a residential garage:

A gas-fired furnace for installation in a residential garage must be
installed so the burner(s) and the ignition source are located not less
than 18 inches (46 cm) above the floor, and the furnace must be located
or protected to avoid physical damage by vehicles.

Floor/

Bottom

1 (25.4)

When replacing an existing furnace, if the existing plenum is not the
same size as the new furnace then the existing plenum must be
removed and a new plenum installed that is the proper size for the new
furnace. If the plenum is shorter than 12” (30.5 cm) the turbulent air flow
may cause the limit controls not to operate as designed, or the limit con­trols may not operate at all.

The duct system is a very important part of the installation. If the duct

system is improperly sized the furnace will not operate properly.

The ducts attached to the furnace plenum, should be of sufficient size
so that the furnace operates at the specified external static pressure
and within the air temperature rise specified on the nameplate.

The minimum plenum height is 12” (30.5 cm). The furnace will not
operate properly on a shorter plenum height. The minimum recom­mended rectangular duct height is 4 inches (10 cm) attached to the
plenum.

If a matching cooling coil is used, it may be placed directly on the fur­nace outlet and sealed to prevent leakage. If thermoplastic evaporator
‘A’ coil drain pans are to be installed in the upflow/horizontal configura­tion, then extra 2” minimum spacing may be needed to ensure against
drain pan distortion.

The duct system must be properly sized to obtain the correct airflow
for the furnace size that is being installed.

Refer to Table6, "Ratings & Physical / Electrical Data" or the fur­nace rating plate for the correct rise range and static pressures.

If the ducts are undersized, the result will be high duct static pres­sures and/or high temperature rises which can result in a heat
exchanger OVERHEATING CONDITION. This condition can result
in premature heat exchanger failure, which can result in personal
injury, property damage, or death.

Closet Alcove Attic

1

Yes Yes Yes No

Line

Contact

Yes

2

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368261-UIM-A-0508

DUCT FLANGES

Four flanges are provided to attach ductwork to the furnace. These
flanges are rotated down for shipment. In order to use the flanges,
remove the screw holding an individual flange, rotate the flange so it is
in the upward position and reinstall the screw then repeat this for all 4
flanges.

If the flanges are not used, they should remain in the rotated down posi­tion as shipped.

For duct attachment,
if needed.

Factory
installed

FIGURE 1: Duct Attachment

DUCTWORK INSTALLATION AND SUPPLY PLENUM
CONNECTION - UPFLOW/HORIZONTAL

Attach the supply plenum to the furnace outlet. The use of
an approved flexible duct connector is recommended on all
installations. This connection should be sealed to prevent
air leakage. The sheet metal should be crosshatched to
eliminate any popping of the sheet metal when the indoor
fan is energized.

FLOOR BASE AND DUCTWORK INSTALLATION ­DOWNFLOW

Installations on combustible material or directly on any
floors must use a combustible floor base shown in Figure 8,
"Combustible Floor Base Accessory". Follow the instruc­tions supplied with the combustible floor base accessory.
This combustible floor base can be replaced with a match­ing cooling coil, properly sealed to prevent leaks. Follow the
instructions supplied with the cooling coil cabinet for install­ing the cabinet to the duct connector. Plug intake and vent
pipe holes in bottom panel and move grommet to desired
vent side exit.

Downflow Air Conditioning Coil Cabinet

The furnace should be installed with coil cabinet part number specifi­cally intended for downflow application. If a matching cooling coil is
used, it may be placed directly on the furnace outlet and sealed to pre­vent leakage. For details of the coil cabinet dimensions and installation
requirements, refer to the installation instructions supplied with the coil
cabinet.

Attach the air conditioning coil cabinet to the duct connector, and then
position the furnace on top of the coil cabinet. The connection to the fur­nace, air conditioning coil cabinet, duct connector, and supply air duct
must be sealed to prevent air leakage.

COIL INSTALLATION

COIL/FURNACE ASSEMBLY - MC/FC/PC SERIES
COILS

Furnace

Furnace

UPFLOW

DOWNFLOW

FIGURE 2: Vertical Applications

FURNACE ASSEMBLY - MC & FC SERIES COILS

These coils are factory shipped for installation in either upflow or down­flow applications with no conversion.

Position the coil casing over or under the furnace opening as shown in
Figure 2, "Vertical Applications" after configuring coil flanges as
required see “Coil Flange” section below.

COIL FLANGE INSTALLATION

The coils include removable flanges to allow proper fit up with furnaces
having various inlet and outlet flange configurations. The two flanges
are attached to the top of the coil in the factory during production. For
proper configuration of flanges refer to Figure 3, "Coil Flange".

FACTORY

FLANGE

LOCATION

(Used for upflow

or horizontal

ALTERNATE
FLANGE LOCATION
(Used for downflow or
horizontal left installations)

right installations)

FIGURE 3: Coil Flange

FURNACE ASSEMBLY - MC SERIES COILS ONLY

MC coils are supplied ready to be installed in a horizontal position. A
horizontal pan is factory installed. MC coils should be installed in all hor­izontal applications with the horizontal drain pan side down.

On all installations without a coil, a removable access panel is rec-

Mounting Plate

ommended in the outlet duct such that smoke or reflected light
would be observable inside the casing to indicate the presence of
leaks in the heat exchanger. This access cover shall be attached in
such a manner as to prevent leaks.

Furnace

FIGURE 4: Horizontal Right Application

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368261-UIM-A-0508

For horizontal left hand applications no conversion is required to an MC
coil when used with a downflow/horizontal furnace. A mounting plate,
supplied with every coil should always be installed on the side desig­nated as top side. See Figures 4 & 5.

Mounting Plate

Furnace

FIGURE 5: Horizontal Left Application

FURNACE ASSEMBLY - PC SERIES COILS

These upflow coils are designed for installation on top of upflow fur­naces only.

If the coil is used with a furnace of a different size, use a 45° transition
to allow proper air distribution through the coil.

1. Position the coil casing over the furnace opening as shown in Fig­ure 6, "PC Series Upflow Coil Installation".

2. Place the ductwork over the coil casing flange and secure.

3. Check for air leakage between the furnace and coil casing and
seal appropriately.

Do not drill any holes or drive any screws into the front duct
flange on the coil in order to prevent damaging coil tubing. See
Figure 6, "PC Series Upflow Coil Installation"

C

(Min)

D

CRITICAL COIL PROJECTION

The coil assembly must be located in the duct such that a minimum dis­tance is maintained between the top of the coil and the top of the duct.
Refer to Table 2, "Coil Projection Dimensions - PC Series Coils".

COIL / FURNACE ASSEMBLY - HC SERIES COILS

These coils are supplied ready to be installed in a right hand position or
a left hand position. When used in conjunction with a horizontal furnace
(blow through) application, the coil should be oriented with the opening
of the “A” coil closest to the furnace. See Figures 7.

NOTE: Each coil is shipped with an external tie plate that should be
used to secure the coil to the furnace. It should be installed on the back
side of the coil using the dimpled pilot holes. See Figures 7.

Use tie plate
supplied with coil

Gas Furnace

Air flow

FIGURE 7: Horizontal Left or Right application (Right Shown)

DOWNFLOW DUCT CONNECTORS

All downflow installations must use a suitable duct connector approved
by the furnace manufacturer for use with this furnace. The duct connec­tors are designed to be connected to the rectangular duct under the
floor and sealed. Refer to the instructions supplied with the duct con­nector for proper installation. Refer to the separate accessory parts list
at the end of these instructions for the approved accessory duct con­nectors.

Flexible
Duct Collar

Field
Fabricated
Ductwork

Upflow
Coil

Upflow
Furnace

Primary

Drain

Secondary

Drain

Do not drill
or Screw
this flange

Alternate

Drain Location

FIGURE 6: PC Series Upflow Coil Installation

Table 2: Coil Projection Dimensions - PC Series Coils

COIL SIZE DIMENSION “C” INCH

PC18 3-1/2
PC24 4-1/2

PC30, PC32, PC35 4-1/2

PC42, PC43, PC36, PC37 5-1/2

PC48 6-1/2
PC60 9

NOTE: Dimension “C” should be at least 2/3 of dimension “D”. See Fig­ure 6, "PC Series Upflow Coil Installation"

FURNACE

WARM AIR PLENUM
WITH 1” FLANGES

FIBERGLASS
INSULATION

FIBERGLASS TAPE
UNDER FLANGE

COMBUSTIBLE FLOOR
BASE ACCESSORY

FIGURE 8: Combustible Floor Base Accessory

RESIDENTIAL AND MODULAR HOME UPFLOW
RETURN PLENUM CONNECTION

Return air may enter the furnace through the side(s) or bottom depend­ing on the type of application. Return air may not be connected into the
rear panel of the unit.

6 Johnson Controls Unitary Products

BOTTOM RETURN AND ATTIC INSTALLATIONS

Bottom return applications normally pull return air through a base plat­form or return air plenum. Be sure the return platform structure or return
air plenum is suitable to support the weight of the furnace.

The internal bottom panel must be removed for this application.
Attic installations must meet all minimum clearances to combustibles

and have floor support with required service accessibility.

HORIZONTAL APPLICATION

FIGURE 9: Horizontal Application

This furnace may be installed in a horizontal position on either side
as shown above. It must not be installed on its back.

368261-UIM-A-0508

When a furnace is installed in an attic or other insulated space,
keep all insulating materials at least 12 inches (30.5 cm) away from
furnace and burner combustion air openings.

SUSPENDED FURNACE / CRAWL SPACE
INSTALLATION

The furnace can be hung from floor joists or installed on suitable blocks
or pad. Blocks or pad installations shall provide adequate height to
ensure the unit will not be subject to water damage. Units may also be
suspended from rafters or floor joists using rods, pipe angle supports or
straps. Angle supports should be placed at the supply air end and near
the blower deck. Do not support at return air end of unit. All four sus­pension points must be level to ensure quite furnace operation. When
suspending the furnace use a secure platform constructed of plywood
or other building material secured to the floor joists. Refer to for typical
crawl space installation.

ATTIC INSTALLATION

Line contact only permissible
between lines formed by the
intersection of furnace top
and two sides and building
joists, studs or framing

Filter rack
must be a minimum
distance
of 18” (45.7 cm)
from the
furnace

Return
Air

Gas Piping

Sediment

Trap

30” MIN.
Work Area

FIGURE 10: Typical Attic Installation

This appliance is certified for line contact when the furnace is installed
in the horizontal left or right position. The line contact is only permissible
between lines that are formed by the intersection of the top and two
sides of the furnace and the building joists, studs or framing. This line
may be in contact with combustible material. Refer to Figure 10, "Typi­cal Attic Installation".

12”

12”

Supply
Air

Vent (Maintain
required
clearances to
combustibles)

Sheet metal in
front of furnace
combustion air
Openings is
Recommended

Angle Iron
Bracket

6” Min. Between
Rod & Front of Furnace

1” Max. Between
Rod & Back of Furnace

Support
Bracket

FIGURE 11: Typical Suspended Furnace / Crawl Space Installation

DOWNFLOW APPLICATION

To apply the furnace in a downflow position, it will be necessary to
rotate the vent blower 90° left or right so that the vent pipe passes
through the side of the furnace casing rather than the end. See Figure
12, "Downflow Venting".

For modulating furnaces to be used in the downflow position, it is
necessary to rotate the gas valve so that it is upright when the fur­nace is installed. Loosen the pipe union between the gas valve and
manifold, rotate the valve as far upward as it will go, and tighten the
union. See Figure 13, "Downflow Installation - Gas Valve Rotation".

For downflow
installation,rotate

Rotate vent
blower 90°

gas valve upwards,
as shown

either way

LEFT SIDE VENT

RIGHT SIDE VENT

FIGURE 12: Downflow Venting FIGURE 13: Downflow Installation - Gas Valve Rotation

Johnson Controls Unitary Products 7

368261-UIM-A-0508

LEFT SIDE

(For Cladded door add

appoximately an additional .75”)

.5”

B

.5”

24.38”

SUPPLY END

20”

28.5”

29.5”

Vent
Outlet

Electrical
Entry

Gas Pipe
Entry

Thermostat
Wiring

Vent
Outlet

C

FRONT

A

33”

Electrical
Entry

Vent Outlet

Gas Pipe
Entry

Thermostat
Wiring

B

RIGHT SIDE

23”

24.25”

RETURN END

FIGURE 14: Dimensions
Table 3: Cabinet and Duct Dimensions

BTUH (kW)

Input

Nominal

CFM (m

3

/min)

Cabinet

Size

AA (cm)BB (cm)CC (cm) Lbs

Cabinet Dimensions (Inches)

60 (17.6) 1200 (34.0) A 14 1/2 36.8 13 1/2 34.3 10.3 26.2 94
80 (23.4) 1200 (34.0) B 17 1/2 44.4 16 1/2 41.9 11.8 29.9 103

80 (23.4) 1600 (45.3) C 21 53.3 20 50.8 13.6 34.5 114
100 (29.3) 1600 (45.3) C 21 53.3 20 50.8 13.6 34.5 118
100 (29.3) 2000 (56.6) C 21 53.3 20 50.8 13.6 34.5 122
120 (35.1) 2000 (56.6) C 21 53.3 20 50.8 15.8 40.1 129

14”

1.5”

.5”

1”

.5”

Approximate

Operating Weights

SECTION III: FILTERS

FILTER INSTALLATION

All applications require the use of a field installed filter. All filters and
mounting provision must be field supplied.

Filters must be installed external to the furnace cabinet. DO NOT

attempt to install filters inside the furnace.
Table 4: Recommended Filter Sizes (High Velocity 600 FPM)

CFM

(m³/min)

1200 (34.0) A 16 x 25 14 x 25
1200 (34.0) B 16 x 25 16 x 25
1600 (45.3) C 16 x 25 20 x 25
2000 (56.6) C (2) 16 x 25 20 x 25

NOTES:

1.Air velocity through throwaway type filters may not exceed 300 feet per
minute (91.4 m/min). All velocities over this require the use of high velocity
filters.

2.Do not exceed 1800 CFM using a single side return and a 16x25 filter. For
CFM greater than 1800, you may use two side returns or one side and the
bottom or one side return with a transition to allow use of a 20x25 filter.

Cabinet

Size

Side

(in)

Bottom

(in)

SIDE RETURN

Locate the “L” shaped corner locators. These indicate the size of the cut­out to be made in the furnace side panel. Refer to Figure 15, "Side
Return Cutout Markings".

Front of
Furnace

Side of
Furnace

Corner
Markings

FIGURE 15: Side Return Cutout Markings
Install the side filter rack following the instructions provided with that

accessory. If a filter(s) is provided at another location in the return air
system, the ductwork may be directly attached to the furnace side
panel.

Some accessories such as electronic air cleaners and pleated
media may require a larger side opening. Follow the instructions
supplied with that accessory for side opening requirements. Do not
cut the opening larger than the dimensions shown in Figure 14,
"Dimensions".

8 Johnson Controls Unitary Products

368261-UIM-A-0508

HORIZONTAL APPLICATION

Horizontal Filters

All filters and mounting provision must be field supplied. All installa­tions must have a filter installed.

Any branch duct (rectangular or round duct) attached to the plenum
must attach to the vertical plenum before the filter. The use of straps
and / or supports is required to support the weight of the external filte r
box.

Downflow Filters

Downflow furnaces typically are installed with the filters located above
the furnace, extending into the return air plenum or duct. Any branch
duct (rectangular or round duct) attached to the plenum must attach to
the vertical plenum above the filter height.

Filter(s) may be located in the duct system external to the furnace using
an external duct filter box attached to the furnace plenum or at the end
of the duct in a return filter grille(s). The use of straps and/or supports is
required to support the weight of the external filter box.

SECTION IV: GAS PIPING

GAS SAFETY

An overpressure protection device, such as a pressure regulator,
must be installed in the gas piping system upstream of the furnace
and must act to limit the downstream pressure to the gas valve so it
does not exceed 0.5 PSI (14" w.c. (3.48 kPa). Pressures exceeding

0.5 PSI (14” w.c. (3.48 kPa) at the gas valve will cause damage to
the gas valve, resulting in a fire or explosion or cause damage to
the furnace or some of its components that will result in property
damage and loss of life.

External Manual
Shutoff Valve

To Gas
Supply

Drip Leg

FIGURE 17: Upflow/Downflow Gas Piping

FIGURE 18: Horizontal Gas Piping

An accessible manual shutoff valve must be installed upstream of
the furnace gas controls and within 6 feet (1.8 m) of the furnace.

Grounded Joint Union

may be Installed

Inside or Outside Unit.

Manual
Shut-off
Valve

Gas
Pipe

Gas
Pipe

Drip
Leg

To Gas
Supply

Drip
Leg

Gas Burners

Gas Valve

Manual
Shut-off Valve

On/Off
Knob

Inlet
Pressure
Tap

FIGURE 16: Gas Valve

Plan your gas supply before determining the correct gas pipe entry.
Use 90-degree service elbow(s), or short nipples and conventional
90-degree elbow(s) to enter through the cabinet access holes.

Main
Regulator
Adjustment

Outlet
Pressure
Tap

GAS PIPING INSTALLATION

Properly sized wrought iron, approved flexible or steel pipe must be
used when making gas connections to the unit. If local codes allow the
use of a flexible gas appliance connection, always use a new listed con­nector. Do not use a connector that has previously serviced another gas
appliance.

Some utility companies or local codes require pipe sizes larger than the
minimum sizes listed in these instructions and in the codes. The furnace
rating plate and the instructions in this section specify the type of gas
approved for this furnace - only use those approved gases. The instal­lation of a drip leg and ground union is required. Refer to Figure 17,
"Upflow/Downflow Gas Piping".

The furnace must be isolated from the gas supply piping system by
closing its individual external manual shutoff valve during any pressure
testing of the gas supply piping system at pressures equal to or less
than 1/2 psig (3.5 kPa).

The gas valve body is a very thin casting that cannot take any
external pressure. Never apply a pipe wrench to the body of the gas
valve when installing piping. A wrench must be placed on the octa­gon hub located on the gas inlet side of the valve. Placing a wrench
to the body of the gas valve will damage the valve causing improper
operation and/or the valve to leak.

Gas piping may be connected from either side of the furnace using any
of the gas pipe entry on both sides of the furnace. Refer to Figure 14,
"Dimensions".

GAS CONVERSION FOR PROPANE (LP)

This furnace is constructed at the factory for natural gas-fired operation,
but may be converted to operate on propane (LP) gas by using a fac­tory-supplied LP conversion kit which includes a LP gas valve. Follow
the instructions supplied with the LP kit.

LoNOx furnaces requiring propane (LP) gas must have the LoNOx
screens removed prior to installation and operation. See propane
instructions.

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368261-UIM-A-0508

HIGH ALTITUDE NATURAL GAS ORIFICE
CONVERSION

The National Fuel Gas Code requires that gas appliances installed
above 2,000 feet elevation have their inputs de-rated by 4% per 1,000
feet above sea level. The modulating furnaces automatically de-rate for
altitude by measuring the inducer blower pressure and using that to
determine if there is adequate air to support good combustion. If there
is not enough combustion air to properly support 100% of the furnace
nameplate input rate, the control will reduce the input to the point that
there will be good combustion.

The factory gas orifice sizes are based on a ga s heating value of
1030 BTU/Cu.ft., so if your gas value is significantly higher or
lower than that, it may be necessary to change to smaller or larger
gas orifices.

The chart below shows recommended gas orifice sizes to use at vari­ous altitudes and at various de-ration levels. To use the chart, follow
these instructions:

1. Clock the gas meter and calculate the actual input rate using your
local gas heating value. See "CALCULATING THE FURNACE
INPUT (NATURAL GAS)" in this manual.

2. Divide that input rate by the input rate shown on the furnace rating
plate to get the actual de-ration percent.

3. Read down the left-hand “Actual Rate” column to find the closest
number to your actual de-ration percent.

4. Read across that row to the column for the elevation at your loca­tion. The number listed there is the orifice size that is proper for
your unit.

Example – You have a 100,000 BTU/H furnace installed at an elevation
of 6,000 feet. You clock the gas meter and find that the furnace is actu­ally fired at 64,000 BTU/H. Divide 64,000 by 100,000, which gives 0.64
(64%). The closest number to 64% in the left-hand “Actual Rate” col­umn is 65. Read across that row to the column for 6,000 feet elevation,
which shows “#43”. You should change from the factory #45 orifices to
larger #43 orifices, which will bring the input rate back up to approxi­mately 76,000 BTU/H, which is what it should be for that furnace at
6,000 feet.

Table 5: High Altitude Orifices

Actual Rate

(percent of

nameplate)

100 48 49 49 50 51 51 52

95 47 48 49 50 50 50 51
90 46 47 48 49 49 49 50
85 45 46 47 48 49 49 50
80 45 45 46 47 48 48 49
75 44 45 45 45 47 47 49
70 43 44 44 45 45 45 48
65 42 43 43 44 45 45 47
60 41 42 42 43 44 45 46
55 40 41 41 32 43 43 44
50 39 40 40 40 43 42 42

4,000 5,000 6,000 7,000 8,000 9,000 10,000

84% 80% 76% 72% 68% 64% 60%

Elevation in Feet Above Sea Level

Orifice Drill Size

PROPANE KITS

It is very important to choose the correct kit and/or gas orifices for the altitude and the type of gas for which the furnace is being installed.
Only use natural gas in furnaces designed for natural gas. Only use propane (LP) gas for furnaces that have been properly converted to use pro-

pane (LP) gas. Do not use this furnace with butane gas.
Incorrect gas orifices or a furnace that has been improperly converted will create an extremely dangerous condition resulting in premature heat

exchanger failure, excessive sooting, high levels of carbon monoxide, personal injury, property damage, a fire hazard and/or death.
Propane (LP) conversions are required in order for the appliance to satisfactory meet the application.
An authorized distributor or dealer must make all gas conversions.
In Canada, a certified conversion station or other qualified agency, using factory specified and/or approved parts, must perform the conversion.
The installer must take every precaution to insure that the furnace has been converted to the proper gas orifice size when the furnace is installed.
Do not attempt to drill out any orifices to obtain the proper orifice size. Drilling out a gas orifice will cause misalignment of the burner flames,
causing premature heat exchanger burnout, high levels of carbon monoxide, excessive sooting, a fire hazard, personal injury, property damage
and/or death.

SECTION V: ELECTRICAL POWER

ELECTRICAL POWER CONNECTIONS

Field wiring to the unit must be grounded. Electric wires that are field
installed shall conform to the temperature limitation for 63°F (35°C) rise
wire when installed in accordance with instructions. Refer to Table 6,
"Ratings & Physical / Electrical Data" in these instructions for specific
furnace electrical data.

Table 6: Ratings & Physical / Electrical Data

Input

Max/Min

MBH kW MBH kW CFM
60/30 17.6/8.8 48/24 14.1/7.0 1200 34.0 7.0 80.0 35-65 19-36 20-50 11-28 15 14 165 73.9
80/40 23.5/11.8 64/32 18.8/9.4 1200 34.0 7.5 80.0 40-70 22-39 20-50 11-28 15 14 170 76.7

80/40 23.5/11.8 64/32 18.8/9.4 1600 45.3 10.0 80.0 40-70 22-39 20-50 11-28 15 14 170 76.7

100/50 29.3/14.7 80/40 23.4/11.7 1600 45.3 10.0 80.0 40-70 22-39 20-50 11-28 15 14 170 76.7
100/50 29.3/14.7 80/40 23.4/11.7 2000 56.6 17.0 80.0 35-65 19-36 20-50 11-28 20 12 165 73.9
120/60 33.7/16.9 96/48 28.1/14.1 2000 56.6 17.0 80.0 45-75 25-42 25-55 13-31 20 12 175 79.4

Annual Fuel Utilization Efficiency (AFUE) numbers are determined in accordance with DOE Test procedures.
Wire size and over current protection must comply with the National Electrical Code (NFPA-70-latest edition) and all local codes.

Output

Max/Min

Nominal

Airflow

3

m

/min

Total Unit

Amps

Air Temp. Rise

AFUE

Use copper conductors only.

Air Temp. Rise

Max Input

°F °C °F °C °F °C

Min Input

Max

Over-Current

Protect

Min. wire Size

(awg) @ 75 ft

one way

Max. Outlet

Air Temp

10 Johnson Controls Unitary Products

368261-UIM-A-0508

SUPPLY VOLTAGE CONNECTIONS

Junction
Box

Connect ground
lead to screw

Electrical Entry

BLK

L1-Hot

Neutral

FIGURE 19: Electrical Wiring

1. Provide a power supply separate from all other circuits. Install
overcurrent protection and disconnect switch per local/national
electrical codes. The switch should be close to the unit for conve­nience in servicing. With the disconnect or fused switch in the OFF
position, check all wiring against the unit wiring label. Refer to the
wiring diagram in this instruction.

2. Remove the screws retaining the wiring box cover. Route the
power wiring through the opening in the unit into the junction box
with a conduit connector or other proper connection. In the junc­tion box there will be 3 wires, a Black Wire, a White Wire. Connect
the power supply as shown on the unit-wiring label on the inside of
the blower compartment door or the wiring schematic in this sec­tion. The black furnace lead must be connected to the L1 (hot)
wire from the power supply. The white furnace screw must be con­nected to neutral. Connect the power supply ground to the green
screw (equipment ground) An alternate wiring method is to use a
field provided 2” (5.1 cm) x 4” (10.2 cm) box and cover on the out­side of the furnace. Route the furnace leads into the box using a
protective bushing where the wires pass through the furnace
panel. After making the wiring connections replace the wiring box
cover and screws. Refer to Figure 19, "Electrical Wiring".

3. The furnace's control system requires correct polarity of the power
supply and a proper ground connection. Refer to Figure 19, "Elec­trical Wiring"

The power connection leads and wiring box may be relocated to the
left side of the furnace. Remove the screws and cut wire tie holding
excess wiring. Reposition on the left side of the furnace and fasten
using holes provided.

WHT

LOW VOLTAGE CONTROL WIRING CONNECTIONS

Install the field-supplied thermostat by following the instructions that
come with the thermostat. With the thermostat set in the OFF position
and the main electrical source disconnected, connect the thermostat
wiring from the wiring connections on the thermostat to the terminal
board on the ignition module, as shown in Figures 20-25, Thermostat
Charts. Electronic thermostats may require the common wire to be con­nected as shown in Figure 16, "Gas Valve". Apply strain relief to ther­mostat wires passing through cabinet.

Set the heat anticipator in the room thermostat to 0.4 amps. Setting
it lower will cause short cycles. Setting it higher will cause the room
temperature to exceed the set points.

Some electronic thermostats do not have adjustable heat anticipa­tors. They should be set to six cycles per hour. Follow the thermo­stat manufacturer's instructions.

The 24-volt, 40 VA transformer is sized for the furnace components
only, and should not be connected to power auxiliary devices such as
humidifiers, air cleaners, etc. The transformer may provide power for an
air conditioning unit contactor.

AIR CONDITIONER CONNECTIONS

This furnace may be used with single-stage or two-stage air condition­ing units.

For Single-Stage A/C - Connect the low voltage wiring as shown in
Figures 20, Thermostat Chart.

For Two-Stage A/C - Use a two-stage thermostat, connect the low volt­age wiring as shown in Figures 21, Thermostat Chart.

For Two-Stage A/C using a Single-Stage Thermostat - connect the
low voltage wiring as shown in Figures 21, Thermostat Chart.

This furnace control board can control a two-stage A/C using only a sin­gle-stage thermostat. In this case, the furnace control switches between
high cool and low cool based on the calculated cooling load.

ZONING OPERATION

This furnace may be used in zoning systems, using a separate after­market zoning control. For use in zoned systems, put the ZONE CON­TROL jumper on the furnace control board in the “YES” position.

HEAT PUMP OPERATION

This furnace may be used in conjunction with a heat pump in dual fuel
applications. For heat pump applications, put the HEAT PUMP jumper
on the furnace control board in the “YES” position. Connect the low volt­age wiring as shown in Figures 20-25, Thermostat Charts. If a two­stage heat pump is to be used, a two-stage thermostat is required.

Johnson Controls Unitary Products 11

368261-UIM-A-0508

For additional connection diagrams for all UPG equipment refer to “Low Voltage System Wiring” document available online at www.upgnet.com in the
Product Catalog Section.

ID MODELS

TM(8,L)M
YM(8,L)M

THERMOSTAT

CM(8,L)M

LM(8,L)M

*PP11C70224

Y

Full Stage Compressor

RH
24 – Volt Hot
(Heat XFMR)

G

Fan

RC
24 – Volt Hot
(Cool XFMR)

W

Full Stage Heat

HM1

Humidistat

External Humidistat

2

(Optional)

Open on Humidity Rise

Clipping Jumper W914 for
electric heat on thermostat

is not necessary

MODULATING

FURNACE

MODULATING

FURNACE CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

G

Fan

W

Modulating Heat

Y/Y2

Second or Full

Stage Compressor

O

Reversing Valve

Energized in Cool

LO COMP

Single Stage

Compressor (OUT)

HI COMP

Second Stage

Compressor (OUT)

DHUM

Dehumidification-

Open on Humidity Rise

Move HUMIDISTAT

jumper to “YES”

if humidistat is to be used.

SINGLE STAGE
SINGLE STAGE

AIR

AIR CONDITIONER

CONDITIONER

1

C

24 – Volt Common

Y

Y

Compressor

Compressor Contactor

2

Part Number:

S1-2HU16700124

Part Numbers:

SAP = Legacy

1

FIGURE 20: Thermostat Chart - Single Stage Air Conditioner – Variable Speed or PSC Modulating Furnace

12 Johnson Controls Unitary Products

THERMOSTAT

THERMOSTAT

368261-UIM-A-0508

ID MODELS

TM(8,L)M
YM(8,L)M
CM(8,L)M

LM(8,L)M

*DN22U00124

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

(Heat XFMR)

G

Fan

E/W1

First Stage Heat

W2

Second Stage Heat

R

24 – Volt Hot

(Cool XFMR)

Y2

Second Stage

Compressor

*PP32U70124

C

24 – Volt Common

Y1

First Stage Compressor

R
24 – Volt Hot
(Heat XFMR)

G

Fan

E/W1

Emergency Heat

AUX

Auxiliary Heat

R
24 – Volt Hot
(Cool XFMR)

Y2

Second Stage

Compressor

MODULATING

FURNACE

MODULATING

FURNACE CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

G

Fan

W

Modulating Heat

Y/Y2

Second or Full

Stage Compressor

O

Reversing Valve

Energized in Cool

LO COMP

Single Stage

Compressor (OUT)

HI COMP

Second Stage

Compressor (OUT)

TWO STAGE

AIR

CONDITIONER

1

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

Y2

Second Stage

Compressor

DHUM

Dehumidification-

Open on Humidity Rise

Move HUMIDISTAT

jumper to “YES”

if humidistat is to be used.

Part Numbers:

SAP = Legacy

1

Connection of the “C”

terminal, 24-volt common

is optional when used with

batteries

Thermostat Installer Setup

1-System Type-must

be set to 6-2 Heat/2 Cool

Multistage Conventional

Thermostat Installer Setup
15-Compressor Protection

-must be set to 5

External Humidistat

2

2

(Optional)

Open on Humidity Rise

Connection of the “C”

terminal, 24-Volt common

is optional when used with

batteries

Thermostat Installer Setup

0170-System Type-must

be set to 8-2 Heat/2 Cool

Multistage Conventional

Part Number:

S1-2HU16700124

FIGURE 21: Thermostat Chart - Two Stage Air Conditioner – Variable Speed or PSC Modulating Furnace

Johnson Controls Unitary Products 13

368261-UIM-A-0508

THERMOSTAT

ID MODELS

TM(8,L)M
YM(8,L)M
CM(8,L)M

LM(8,L)M

*PP11C70224

Y

Full Stage Compressor

RH

24 – Volt Hot

(Heat XFMR)

G

Fan

RC
24 – Volt Hot
(Cool XFMR)

W

Full Stage Heat

HM1

Humidistat

External Humidistat

2

(Optional)

Open on Humidity Rise

Clipping Jumper W914 for

electric heat on thermostat

is not necessary

MODULATING

FURNACE

MODULATING

FURNACE CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

G

Fan

W

Modulating Heat

Y/Y2

Second or Full

Stage Compressor

O

Reversing Valve

Energized in Cool

LO COMP

Single Stage

Compressor (OUT)

HI COMP

Second Stage

Compressor (OUT)

DHUM

Dehumidification-

Open on Humidity Rise

Move HUMIDISTAT

jumper to “YES”

if humidistat is to be used.

TWO STAGE

AIR

CONDITIONER

1

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

Y2

Second Stage

Compressor

2

Part Number:

S1-2HU16700124

Part Numbers:

SAP = Legacy

1

FIGURE 22: Thermostat Chart - Two Stage Air Conditioner with Single Stage Thermostat – Variable Speed or PSC Modulating Furnace

14 Johnson Controls Unitary Products

368261-UIM-A-0508

THERMOSTAT

*DN22U00124

N/A

THERMOSTAT

*BP21H50124
*BN21H00124
*DP21H40124

*DN21H00124

N/A

THERMOSTAT

*DP32H70124

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

G

Fan

E

Emergency Heat

W2

Third Stage Heat

O

Reversing Valve

Energized in Cool

L

Malfunction Light

Second Stage Compressor

3

Y2

W1

Second Stage Aux. Heat

External Humidistat

(Optional)

Open on Humidity Rise

ID MODELS

TM(8,L)M
YM(8,L)M
CM(8,L)M

LM(8,L)M

MODULATING

FURNACE

MODULATING

FURNACE CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

G

Fan

W

Modulating Heat

Y/Y2

Second or Full

Stage Compressor

O

Reversing Valve

Energized in Cool

LO COMP

Single Stage

Compressor (OUT)

HI COMP

Second Stage

Compressor (OUT)

DHUM

Dehumidification-

Open on Humidity Rise

OD MODELS

E*R*

E*ZD

E*B*

*RHS

HP*

*HGD

SINGLE STAGE

HEAT PUMP

2

DEMAND DEFROST

CONTROL

C

24 – Volt Common

Y

Compressor

R

24 – Volt Hot

W1/66(out)

Heat

O

Reversing Valve

Energized in Cool

X/L

Malfunction Light

W

Auxiliary Heat

1

Step 1 of Thermostat

Installer / Configuration

Menu must be set to

Heat Pump 1

Step 9 of Thermostat

Installer / Configuration

Menu must be set to

Pump OFF

3

Part Number:

S1-2HU16700124

Move HUMIDISTAT

jumper to “YES”

if humidistat is to be used.

Part Numbers:

SAP = Legacy

2

Part Numbers:

SAP = Legacy

67297 = 031-01975

1

FIGURE 23: Thermostat Chart - Single Stage Heat Pump – Variable Speed or PSC Modulating Furnace

Johnson Controls Unitary Products 15

368261-UIM-A-0508

THERMOSTAT

*DN22U00124

C

24 – Volt Common

Y1

First Stage Compressor

R
24 – Volt Hot
(Heat XFMR)

G

Fan

E

Emergency Heat

R

24 – Volt Hot

(Cool XFMR)

O/B

Reversing Valve

L

Malfunction Light

Y2

Second

Stage Compressor

AUX

Auxiliary Heat

THERMOSTAT

*BP21H50124
*BN21H00124
*DP21H40124
*DN21H00124

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

G

Fan

E

Emergency Heat

O

Reversing Valve

Energized in Cool

L

Malfunction Light

Y2

Second

Stage Compressor

W2

Second Stage Heat

THERMOSTAT

*DP32H70124

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

G

Fan

E

Emergency Heat

W2

Third Stage Heat

O

Reversing Valve

Energized in Cool

L

Malfunction Light

Y2

Second

Stage Compressor

W1

Second Stage Aux. Heat

External Humidistat

3

(Optional)

Open on Humidity Rise

ID MODELS

TM(8,L)M
YM(8,L)M
CM(8,L)M
LM(8,L)M

MODULATING

FURNACE

MODULATING

FURNACE CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

G

Fan

W

Modulating Heat

Y/Y2

Second or Full

Stage Compressor

O

Reversing Valve

Energized in Cool

LO COMP

Single Stage

Compressor (OUT)

HI COMP

Second Stage

Compressor (OUT)

DHUM

Dehumidification-

Open on Humidity Rise

2

Bonnet Sensor

(Optional)

OD MODELS

YZB
YMB

H*3

SINGLE STAGE

HEAT PUMP

YORKGUARD VI

CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

W1 OUT

First Stage Heat

W2 OUT

Second Stage Heat

Y2 OUT
Second

Stage Compressor

O

Reversing Valve

Energized in Cool

X/L

Malfunction Light

Y2

Second

Stage Compressor

W

Auxiliary Heat

BSG

Bonnet Sensor

BS

Bonnet Sensor

1

Thermostat Installer Setup
1-System Type-must be set
to 5 – 2 Heat/1 Heat Pump

Thermostat Installer Setup

2-Changeover Valve-must

be set to 0 – O/B terminal

Energized in Cooling

B/O Switch on Thermostat

must be in the O position

Step 1 of Thermostat

Installer / Configuration

Menu must be set to

Heat Pump 1

3

Part Number:

S1-2HU16700124

Move HUMIDISTAT

jumper to “YES”

if humidistat is to be used.

Part Numbers:

SAP = Legacy

FIGURE 24: Thermostat Chart - Single Stage Heat Pump – Variable Speed or PSC Modulating Furnace

Change FFuel jumper

on the heat pump control

to “ON”

Change Hot Heat Pump

jumper on the heat

pump control to “ON” if

Hot Heat Pump

Operation is desired.

2

Part Numbers:

SAP = Legacy

126768 = 031-09137
18395 = 031-01996
340512 = 031-09178

1

16 Johnson Controls Unitary Products

368261-UIM-A-0508

THERMOSTAT

*PP32U70124

C

24 – Volt Common

Y

First Stage Compressor

R
24 – Volt Hot
(Heat XFMR)

G

Fan

E

Emergency Heat

RC

24 – Volt Hot

(Cool XFMR)

O/B

Reversing Valve

L

Malfunction Light

Y2

Second

Stage Compressor

AUX

Auxiliary Heat

THERMOSTAT

*DN22H00124

*DP22U70124

C

24 – Volt Common

Y1

First Stage Compressor

R

24 – Volt Hot

G

Fan

W2

Second Stage Aux. Heat

O

Reversing Valve

Energized in Cool

L

Malfunction Light

Y2

Second

Stage Compressor

E/W1

First Stage Aux. Heat

External Humidistat

3

(Optional)

Open on Humidity Rise

ID MODELS

TM(8,L)M
YM(8,L)M
CM(8,L)M
LM(8,L)M

MODULATING

FURNACE

MODULATING

FURNACE CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

G

Fan

W

Modulating Heat

Y/Y2

Second or Full

Stage Compressor

O

Reversing Valve

Energized in Cool

LO COMP

Single Stage

Compressor (OUT)

HI COMP

Second Stage

Compressor (OUT)

DHUM

Dehumidification-

Open on Humidity Rise

OD MODELS

YZE

YZH

H*5
H*8

TWO STAGE

HEAT PUMP

2

Bonnet Sensor

(Optional)

YORKGUARD VI

CONTROL

C

24 – Volt Common

Y1

Single

Stage Compressor

R

24 – Volt Hot

W1 OUT

First Stage Heat

W2 OUT

Second Stage Heat

Y2 OUT

Second

Stage Compressor

O

Reversing Valve

Energized in Cool

X/L

Malfunction Light

Y2

Second

Stage Compressor

W

Auxiliary Heat

BSG

Bonnet Sensor

BS

Bonnet Sensor

1

Thermostat Installer Setup

0170-System Type-

must be set to 12

3 Heat/2 Heat Pump

Thermostat Installer Setup

0190-Changeover Valve-

must be set to 0

O/B terminal

Energized in Cooling

Thermostat Installer Setup

0200-Backup Heat Source-

must be set to 1

Heat Pump Backup Heat

Source is Fossil Fuel

Thermostat Installer Setup

0210-External Fossil Fuel

Kit- must be set to 1

Heat Pump Control

is Controlling Heat Pump

Backup Heat

Step 1 of Thermostat

Installer/Configuration

Menu must be set to “HP2”

Selection of GAS/ELEC

switch on thermostat

not necessary

Move HUMIDISTAT

jumper to “YES”

if humidistat is to be used.

Part Numbers:

SAP = Legacy

2

Change FFuel jumper

on the heat pump control

to “ON”

Change Hot Heat Pump

jumper on the heat

pump control to “ON” if

Hot Heat Pump

Operation is desired.

Part Numbers:

SAP = Legacy

126768 = 031-09137
18395 = 031-01996
340512 = 031-09178

1

FIGURE 25: Thermostat Chart - Two Stage Heat Pump – Variable Speed or PSC Modulating Furnace

Johnson Controls Unitary Products 17

368261-UIM-A-0508

)

ACCESSORY CONNECTIONS

The furnace control will allow power-switching control of various acces­sories.

ELECTRONIC AIR CLEANER CONNECTION

Two 1/4” (0.64 cm) spade terminals (EAC and NEUTRAL) for electronic
air cleaner connections are located on the control board. The terminals
provide 115 VAC (1.0 amp maximum) during circulating blower opera­tion.

HUMIDIFIER CONNECTION

Two 1/4” (0.64 cm) spade terminals (HUM and NEUTRAL) for humidi­fier connections are located on the control board. The terminals provide
115 VAC (1.0 amp maximum) during heating system operation.

A mounting hole is provided on the control panel next to the furnace
control board for mounting a humidifier transformer if required.

HUMIDISTAT CONNECTION

For better humidity control during cooling operation, an external humi­distat may be used. When using a external humidistat, put the HUMI­DISTAT jumper in the “YES” position. Connect the low voltage wiring as
shown in Figures 20-25, Thermostat Charts.

SECTION VI: TWINNING AND STAGING

Twinning and staging is NOT allowed for modulating furnaces.

SECTION VII: VENT SYSTEM

VENT CONNECTIONS

Figure 26, "Combustion Air Inducer" shows the furnace as it is shipped
from the factory. To convert to a horizontal or downflow position, remove
the four screws that secure the inducer assembly and rotate 90° being
careful not to damage the gasket. Reinstall screws. Remove cap from
appropriate vent outlet location on the cabinet cut insulation in cabinet
to same size as the hole provided and reinstall cap in the hole in the top
panel.

The furnace shall be connected to a type B vent connector, and
shall be connected to a type B vent only. The furnace shall not be
connected to a chimney flue serving a separate appliance
designed to burn solid fuel. Single-wall vent pipe is not allowed.

It is recommended that the appliance is installed in a location where the
space temperature is 32 °F (0°C) or higher. If the appliance is installed
in a location where the ambient temperature is below 32 °F (0°C), the
combustion byproducts could condense causing damage to the appli­ance heat exchanger.

This appliance may be common vented with another gas appliance for
residential installations as allowed by the codes and standards listed in
these instructions.

VENTING

Category I venting consists of vertically venting one or more appliances
in B-vent or B-vent connectors. Type B-vent system extends in a gen­eral vertical direction and does not contain offsets exceeding 45°. A
vent system having not more than one 60° offset is permitted.

VENTING INTO AN EXISTING CHIMNEY

This furnace may not be connected to any masonry chimney. However,
an existing masonry chimney may be used on as a chase through
which the metal vent pipe passes.

FAN-ASSISTED COMBUSTION SYSTEM

This appliance is equipped with an integral mechanical means to draw
products of combustion through the heat exchanger.

Ambient Combustion Air Supply

This type installation will draw the air required for combustion from
within the space surrounding the appliance and from areas or rooms
adjacent to the space surrounding the appliance. This may be from
within the space in a non-confined location or it may be brought into the
furnace area from outdoors through permanent openings or ducts. A
single, properly sized pipe from the furnace vent connector to the out­doors must be provided. For upflow models combustion air is brought
into the furnace through the unit top panel opening.

In downflow applications, do not block the combustion air inlet. The
furnace must be installed on a coil cabinet or subbase to allow com­bustionair to enter the burner compartment.

COMBUSTION AIR INDUCER

90° 90°

Pressure Switch
Tube Routing

FIGURE 26: Combustion Air Inducer

CATEGORY 1 - 450 F. MAX. VENT TEMP.

The venting system must be installed in accordance with Section 5.3,
Air for Combustion and Ventilation, of the National Fuel Gas Code
Z223.1/NFPA 54 (latest edition), or Sections 7.2, 7.3 or 7.4 of CSA
B149.1, National Gas and Propane Codes (latest edition) or applicable
provisions of the local building code and these instructions.

Mounting Screw
(Remove)

Flue Transition
(Do Not Remove

Pressure
Switch

Mounting Screw
(Remove)

COMBUSTION

AIR

FIGURE 27: Combustion Airflow Path Through The Furnace Casing to

the Burner Compartment

This type of installation requires that the supply air to the appli­ance(s) be of a sufficient amount to support all of the appliance(s)
in the area. Operation of a mechanical exhaust, such as an exhaust
fan, kitchen ventilation system, clothes dryer or fireplace may cre­ate conditions requiring special attention to avoid unsatisfactory
operation of gas appliances. A venting problem or a lack of supply
air will result in a hazardous condition, which can cause the appli­ance to soot and generate dangerous levels of CARBON MONOX­IDE, which can lead to serious injury, property damage and / or
death.

18 Johnson Controls Unitary Products

An unconfined space is not less than 50 cu.ft (1.42 m3) per 1,000 Btu/
hr (0.2928 kW) input rating for all of the appliances installed in that
area.

Rooms communicating directly with the space containing the appli­ances are considered part of the unconfined space, if openings are fur­nished with openings or louvers.

3

A confined space is an area with less than 50 cu.ft (1.42 m

) per 1,000
Btu/hr (0.2928 kW) input rating for all of the appliances installed in that
area. The following must be considered to obtain proper air for combus­tion and ventilation in confined spaces.

Combustion Air Source From Outdoors

The blocking effects of louvers, grilles and screens must be given con­sideration in calculating free area. If the free area of a specific louver or
grille is not known, refer to Table 7, to estimate free area.

Table 7: Estimated Free Area

Wood or Metal

Louvers or Grilles

Screens+

* Do not use less than 1/4”(0.635 cm) mesh
+ Free area of louvers and grille varies widely; the installer should follow

louver or grille manufacturer’s instructions.

Wood 20-25%*
Metal 60-70% *

1/4” (0.635 cm)

mesh or larger 100%

Dampers, Louvers and Grille s (C anada Only)

1. The free area of a supply air opening shall be calculated by sub-

tracting the blockage area of all fixed louvers grilles or screens
from the gross area of the opening.

2. Apertures in a fixed louver, a grille, or screen shall have no dimen-

sion smaller than 0.25” (0.64 cm).

3. A manually operated damper or manually adjustable louvers are

not permitted for use.

4. A automatically operated damper or automatically adjustable lou-

vers shall be interlocked so that the main burner cannot operate
unless either the damper or the louver is in the fully open position.

Gas

Attic

Outlet
Air (a)

Vent

Soffit
Vent

Gable
Vent

Ventilated

Attic

Top Above
Insulation

Soffit
Vent

Gable
Vent

Optional
Inlet (a)

Ventilated

Top Above
Insulation

368261-UIM-A-0508

When a Category I furnace is removed or replaced, the original
venting system may no longer be correctly sized to properly vent
the attached appliances.

An improperly sized vent system can cause CARBON MONOXIDE
to spill into the living space causing personal injury, and or death.

Table 8: Unconfined Space Minimum Area in Square Inch

BTUH Input Rating

60,000

80,000
100,000
120,000

Table 9: Free Area

Minimum Free Area Required for Each Opening

BTUH Input

Rating

60,000

80,000
100,000
120,000

Horizontal Duct

(2,000 BTUH)

30 in
40 in
50 in

60 in
EXAMPLE: Determining Free Area.
Appliance 1 Appliance 2 Total Input

100,000 + 30,000 = (130,000 ÷ 4,000) = 32.5 Sq. In. Vertical
Appliance 1 Appliance 2 Total Input
100,000 + 30,000 = (130,000 ÷ 2,000) = 65 Sq. In. Horizontal

Gas
Vent

Outlet
Air (b)

Minimum Free Area in Square Feet

Required for Each Opening

60 (387 cm

80 (516 cm
100 (645 cm
120 (742 cm

Vertical Duct or

Opening to Outside

(4,000 BTUH)

2

(193 cm2) 15 in2 (97 cm2)

2

(258 cm2) 20 in2 (129 cm2)

2

(322 cm2) 25 in2 (161 cm2)

2

(387 cm2) 30 in2 (193 cm2)

2
2

2
2

Gas
Vent

)
)

)
)

Round Duct

(4,000 BTUH)

5” (13 cm)
5” (13 cm)
6” (15 cm)
7” (18 cm)

Outlet
Air (a)

Gas
Water
Heater

Ventilated

Crawl Space

Furnace

Inlet
Air (b)

Gas
Water
Heater

Furnace

Inlet
Air (a)

Inlet
Air (b)

Gas

Water

Heater

Furnace

Inlet
Air (a)

FIGURE 28: Outside and Ambient Combustion Air

Air Supply Openings and Ducts

1. An opening may be used in lieu of a duct to provide to provide the
outside air supply to an appliance unless otherwise permitted by
the authority having jurisdiction. The opening shall be located
within 12” (30.5 cm) horizontally from, the burner level of the appli­ance. Refer to “COMBUSTION AIR SOURCE FROM OUTDOORS
and VENT AND SUPPLY AIR SAFETY CHECK” in these instruc­tions for additional information and safety check procedure.

2. The duct shall be either metal, or a material meeting the class 1
requirements of CAN4-S110 Standard for Air Ducts.

3. The duct shall be least the same cross-sectional area as the free
area of the air supply inlet opening to which it connects.

4. The duct shall terminate within 12 in (30.5 cm) above, and within
24 in (61 cm) horizontally from, the burner level of the appliance
having the largest input.

5. A square or rectangular shaped duct shall only be used when the
required free area of the supply opening is 9 in

2

(58.06 cm2) or
larger. When a square or rectangular duct is used, its small dimen­sionshall not be less than 3 in (7.6 cm).

6. An air inlet supply from outdoors shall be equipped with a means
to prevent the direct entry of rain and wind. Such means shall not
reduce the required free area of the air supply opening.

7. An air supply inlet opening from the outdoors shall be located not
less than 12” (30.5 cm) above the outside grade level.

Combustion Air Source from Outdoors

1. Two permanent openings, one within 12 in (30.5 mm) of the top
and one within 12 in (30.5 mm) of bottom of the confined space,
Two permanent openings, shall communicate directly or by means
of ducts with the outdoors, crawl spaces or attic spaces.

Johnson Controls Unitary Products 19

368261-UIM-A-0508

2. One permanent openings, commencing within 12 in (30.5 mm)of
the top of the enclosure shall be permitted where the equipment
has clearances of at least 1 in (2.54 cm) from the sides and back
and 6 in (15.24 cm) from the front of the appliance. The opening
shall communicate directly with the outdoors and shall have a min­imum free area of:

a. 1 square in per 3000 Btu per hour (6.45 cm3 per 0.879 kW) of

the total input rating of all equipment located in the enclosure.

b. Not less than the sum of all vent connectors in the confined

space.

3. The duct shall be least the same cross-sectional area as the free
area of the air supply inlet opening to which it connects.

4. The blocking effects of louvers, grilles and screens must be given
consideration in calculating free area. If the free area of a specific
louver or a grille is not known. Refer to Table 7, "Estimated Free
Area" to estimate free area.

Ventilated Combustion Air

The ventilated attic space or a crawl space from which the combustion
air is taken must comply with the requirements specified in “AIR
SOURCE FROM OUTDOORS” in this instruction or in Section 5.3, Air
for Combustion and Ventilation of the National Fuel Gas Code, ANSI
Z223.1 (latest edition). This type installation requires two properly sized
pipes. One brings combustion air from a properly ventilated attic space
or crawl space and a second pipe that extends from the furnace vent
connection (top right of unit) to the exterior of the building.

Vent and Supply (Outside) Air Safety Check Procedure

For Category I furnaces, vent installations shall be in accordance with
Parts 7 and 11 of the National Fuel Gas Code, ANSI Z223.1/NFPA 54,
and or Section 7 and Appendix B of the CSA B149.1, Natural Gas and
Propane Installation Codes, the local building codes, furnace and vent
manufacture's instructions.

Multi-story or common venting systems are permitted and must be
installed in accordance with the National Fuel Gas Code, ANSI Z223.1/
NFPA 54 and / or the CSA B149.1, Natural Gas and Propane Installa­tion Codes, local codes, and the manufacture's instructions.

Vent connectors serving Category I furnaces shall not be connected
into any portion of mechanical draft systems operating under positive
pressure.

Horizontal portions of the venting system shall be supported to prevent
sagging using hangers or perforated straps and must slope upwards
not less than 1/4" per foot (0.635 cm/m) from the furnace to the vent ter­minal.

It is recommended that you follow the venting safety procedure below.
This procedure is designed to detect an inadequate ventilation system
that can cause the appliances in the area to operate improperly causing
unsafe levels of Carbon Monoxide or an unsafe condition to occur.

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 carbon­monxide 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. Inspect the venting system for proper size and horizontal pitch. Determine that there is no blockage, restriction, leakage, corrosion or other
deficiencies, which could cause an unsafe condition

2. Close all building doors and windows and all doors.

3. Turn on clothes dryers and TURN ON any exhaust fans, such as range hoods and bathroom exhausts, so they shall operate at maximum
speed. Open the fireplace dampers. Do not operate a summer exhaust fan.

4. Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so the appliance shall operate contin­uously.

5. Test each appliance (such as a water heater) equipped with a draft hood for spillage (down-draft or no draft) at the draft hood relief opening
after 5 minutes of main burner operation. Appliances that do not have draft hoods need to be checked at the vent pipe as close to the
appliance as possible. Use a combustion analyzer to check the CO2 and CO levels of each appliance. Use a draft gauge to check for a
downdraft or inadequate draft condition.

6. After it has been determined that each appliance properly vents when tested as outlined above, return doors, windows, exhaust fans, fire­place dampers and any other gas burning appliance to their normal condition.

7. If improper venting is observed during any of the above tests, a problem exists with either the venting system or the appliance does not
have enough combustion air (Supply Air from outside) to complete combustion. This condition must be corrected before the appliance can
function safely.

NOTE: An unsafe condition exists when the CO reading exceeds 40 ppm and the draft reading is not in excess of - 0.1 in. W.C. (-25 kPa) with

all of the appliance(s) operating at the same time.

8. Any corrections to the venting system and / or to the supply (outside) air system must be in accorda nce with the National Fuel Gas Code
Z223.1 or CAN/CGA B149.1 Natural Gas and Propane Installation Code (latest editions). If the vent system must be resized, follow the
appropriate tables in Appendix G of the above codes or for this appliance.

SECTION VIII: START-UP AND
ADJUSTMENTS

NOTE: In order that this furnace will operate properly, it is required that
all of the startup procedures in this section be followed.

NOx SCREEN REMOVAL (Lo-NOx Models Only)

If the furnace is equipped with NOx screens and is to be used with LP
(propane) gas, the screens must be removed prior to start-up.

1. Make sure that the electrical power to the unit is turned off and that
the gas supply is turned off at the shut-off valve.

2. Remove the blower compartment and burner compartment access
doors.

3. Disconnect the gas supply piping at the union to permit removal of
the entire burner and gas control assembly from the vestibule
panel. Use the wrench boss on the gas valve when removing or
installing the piping.

4. Unplug the igniter from the wire harness. Disconnect the flame
sensor wires located on top of the air shield. Unplug the gas valve
from the wiring harness.

5. Remove the screws holding the burner assembly to the vestibule
panel.

20 Johnson Controls Unitary Products

368261-UIM-A-0508

6. Remove the burner assembly. It should be possible to swing the
burner assembly out of the way without disconnecting the remain­ing wires.

7. With the burner assembly out of the way, simply slide the NOx
screens out of the heat exchanger tubes and discard the screens.

8. Replace all components in reverse order. Reconnect all wiring.

GAS PIPING LEAK CHECK

FIRE OR EXPLOSION HAZARD

Failure to follow the safety warnings exactly 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.

Burner ignition may not be satisfactory on first startup due to resid­ual air in the gas line or until gas manifold pressure is adjusted. The
ignition control will make three attempts to light before locking out.

It is recommended that when the gas supply is first connected to the
furnace, the ground union be loosened until the odor of gas is detected.
When gas is detected, immediately tighten the union and check for gas
leaks. Allow five minutes for any gas to dissipate before continuing with
the startup procedure. Be sure that proper ventilation is available to
dilute and carry away any vented gas.

With furnace in operation, check all of the pipe joints, gas valve connec­tions and manual valve connections for leakage using an approved gas
detector, a non-corrosive leak detection fluid or other leak detection
methods. Take appropriate action to stop any leak. If a leak persists,
replace the faulty component.

The furnace and its equipment shutoff valve must be disconnected from
the gas supply during any pressure testing of that system at test pres­sures in excess of 1/2 PSI (3.45 kPa).

The furnace must be isolated from the gas supply piping system by
closing the equipment shutoff valve during any pressure testing of the
gas supply system.

SETUP TEST MODE

During normal operation, the furnace input rate can vary between 50%
and 100% of full nameplate input, making it difficult to check for proper
operation. To help with the furnace startup process, the control has a
TEST MODE available that allows the furnace input rate to stay at a
constant input rate. To access this TEST MODE perform the following
sequence:

1. With power to the board on and with no thermostat calls (no call for
heating, cooling or continuous fan), push and hold the TEST but­ton on the board for one second. The LED on the board will glow
red.

2. Release the TEST button. The LED on the board will flash a rapid
green signal, indicating that TEST MODE is activated.

3. Turn the thermostat to call for heat (R & W signal).

4. The furnace will light and operate at high (100%) firing rate. T he
furnace firing rate should be checked at this level to confirm that
the furnace is not overfired or underfired.

5. To run the furnace at minimum rate (50%), press the ERROR but­ton once. The LED will flash one green flash to confirm.

6. To run the furnace at a middle rate (70%), press the ERROR but­ton twice within a five-second period. The LED will flash green two
times to confirm.

7. To again operate the furnace at maximum (1 00%) rate, press the
ERROR button three times within a five-second period. The LED
will flash green three times to confirm.

8. If the thermostat call for heat is removed, the LED will flash a rapid
green signal, indicating that the furnace is still in TEST MODE.

9. When startup tests are completed, turning off power to the board
will take the furnace out of TEST MODE and will restore normal
operation. The furnace will automatically return to normal opera­tion after 150 minutes if power is not cycled.

CALCULATING THE FURNACE INPUT
(NATURAL GAS)

NOTE: Burner orifices are sized to provide proper input rate using natu­ral gas with a heating value of 1030 BTU/Ft
ing value of your gas is significantly different, it may be necessary to
replace the orifices.

NOTE: DO NOT set manifold pressure less than 3.2 in wc or more than

3.8 in wc for natural gas at sea level. If manifold pressure is outside this

range, change main burner orifices.

DO NOT bottom out gas valve regulator adjusting screw. This can
result in unregulated manifold pressure and result in excess over­fire and heat exchanger failures.

NOTE: If orifice hole appears damaged or it is suspected to have been
redrilled, check orifice hole with a numbered drill bit of correct size.
Never redrill an orifice. A burr-free and sqaurely aligned orifice hole is
essential for proper flame characteristics.

DO NOT bottom out gas valve regulator adjusting screw. This can
result in unregulated manifold pressure and result in excess over­fire and heat exchanger failures.

Verify natural gas input rate by clocking meter.

1. Turn off all other gas appliances and pilots.

2. Run furnace for a minimum of 3 minutes in heating operation.

3. Measure time (in sec) for gas meter to complete 1 revolution and
note reading. The 2 cubic feet dial provides a more accurate mea­surement of gas flow.

4. Refer to Table 10, "Gas Rate (CU FT/HR) at Full Input" for cubic
feet of gas per hour.

5. Multiply cubic feet per hour by heating valve (BTU/cu ft) to obtain
input.

If clocked rate does not match the input rate from the unit nameplate.
follow steps in next section to adjust the manifold pressure. Repeat
steps 2 - 5 until correct input is achieved.

Be sure to relight any gas appliances that were turned off at the
start of this input check.

3

(38.4 MJ/m3). If the heat-

Johnson Controls Unitary Products 21

368261-UIM-A-0508

Table 10: Gas Rate (CU FT/HR) at Full Input

Seconds For
1 Revolution

10 360 720 1800 55 65 131 327
11 327 655 1636 56 64 129 321
12 300 600 1500 57 63 126 316
13 277 555 1385 58 62 124 310
14 257 514 1286 59 61 122 305
15 240 480 1200 60 60 120 300
16 225 450 1125 62 58 116 290
17 212 424 1059 64 56 112 281
18 200 400 1000 66 54 109 273
19 189 379 947 68 53 106 265
20 180 360 900 70 51 103 257
21 171 343 857 72 50 100 250
22 164 327 818 74 48 97 243
23 157 313 783 76 47 95 237
24 150 300 750 78 46 92 231
25 144 288 720 80 45 90 225
26 138 277 692 82 44 88 220
27 133 267 667 84 43 86 214
28 129 257 643 86 42 84 209
29 124 248 621 88 41 82 205
30 120 240 600 90 40 80 200
31 116 232 581 92 39 78 196
32 113 225 563 94 38 76 192
33 109 218 545 96 38 75 188
34 106 212 529 98 37 74 184
35 103 206 514 100 36 72 180
36 100 200 500 102 35 71 178
37 97 195 486 104 35 69 173
38 95 189 474 106 34 68 170
39 92 185 462 108 33 67 167
40 90 180 450 110 33 65 164
41 88 176 439 112 32 64 161
42 86 172 429 116 31 62 155
43 84 167 419 120 30 60 150
44 82 164 409 124 29 58 145
45 80 160 400 128 28 56 141
46 78 157 391 133 27 54 135
47 76 153 383 138 26 52 130
48 75 150 375 144 25 50 125
49 73 147 367 150 24 48 120
50 72 144 360 157 23 46 115
51 71 141 355 164 22 44 110
52 69 138 346 171 21 42 105
53 68 136 340 180 20 40 100
54 67 133 333

1 Cu Ft 2 Cu Ft 5 Cu Ft 1 Cu Ft 2 Cu Ft 5 Cu Ft

Size of Test Dial

Seconds For
1 Revolution

Size of Test Dial

22 Johnson Controls Unitary Products

ADJUSTMENT OF MANIFOLD GAS PRESSURE

Be sure to relight any gas appliances that were turned off at the
start of this input check.

Table 11: Inlet Gas Pressure Range

INLET GAS PRESSURE RANGE

Natural Gas Propane (LP)
Minimum* 4.5” W.C. (1.12 kPa) 8.0” W.C. (1.99 kPa)
Maximum 10.5” W.C. (2.61 kPa) 13.0” (3.24 kPa) W.C.

* The gas line pressure MUST BE

• 7” W.C. (1.74 kPA) for Natural Gas

• 11” W.C. (2.74 kPA) for Propane (LP) Gas

in order to obtain the BTU input specified on the rating plate and/or the
nominal manifold pressure specified in these instructions and on the
rating plate.

The inlet gas pressure operating range table specifies what the
minimum and maximum gas line pressures must be for the furnace
to operate safely.

Follow the appropriate section in the instructions below. Refer to Figure
29, "Gas Valve" for a drawing of the locations of the pressure ports on
the gas valve.

T urn gas off at the ball valve or gas cock on gas supply line
before the gas valve.

1. The manifold pressure must be taken at the port marked OUT
PRESS TAP.

2. The inlet gas line pressure must be taken at the port marked IN
PRESS TAP.

3. Using a 3/16” allen wrench, remove the plugs from the inlet and
outlet pressure ports. Connect a 1/8” UPT barbed hose fitting to
each pressure port.

The cap for the pressure regulator must be removed entirely to gain
access to the adjustment screw. Loosening or tightening the cap
does not adjust the flow of gas.

4. Refer to Figure 29, "Gas Valve" for location of pressure regulator
adjustment cap and adjustment screws on main gas valve.

5. Turn gas and electrical supplies on and follow the operating
instructions to place the unit back in operation.

6. Adjust manifold pressure by adjusting gas valve regulator screw
for the appropriate gas per the following:

TABLE 12:

Nominal Manifold Pressure

NOMINAL MANIFOLD PRESSURE

Natural Gas (Max) 3.5" w.c. (0.87 kPa)

Natural Gas (Min) 0.9" w.c. (0.22 kPa)

Propane (LP) Gas (Max) 10.0" w.c. (2.49 kPa)

Propane (LP) Gas (Min) 2.5" w.c. (0.62 kPa)

368261-UIM-A-0508

On/Off
Knob

Inlet
Pressure
Tap

FIGURE 29: Gas Valve

If gas valve regulator is turned in (clockwise), manifold pressure is
increased. If screw is turned out (counterclockwise), manifold pres­sure will decrease.

7. After the manifold pressure has been adjusted, re-calculate the
furnace input to make sure you have not exceeded the specified
input on the rating plate. Refer to "CALCULATING THE FURNACE
INPUT (NATURAL GAS)".

8. Once the correct BTU (kW) input has been established, turn the
gas valve to OFF and turn the electrical supply switch to OFF; then
remove the flexible tubing and fittings from the gas valve pressure
tap and the pressure reference hose from the burner box and
replace the pressure tap plugs. Replace the burner box front cover
(if it was removed) and place the pressure reference hose back on
the gas valve.

9. Turn the electrical and gas supplies back on, and with the burners
in operation, check for gas leakage around the gas valve pressure
port for leakage using an approved gas detector, a non-corrosive
leak detection fluid, or other leak detection methods.

Main
Regulator
Adjustment

Outlet
Pressure
Tap

ADJUSTMENT OF TEMPERATURE RISE

The temperature rise, or temperature difference between the return
air and the supply (heated) air from the furnace, must be within the
range shown on the furnace rating plate and within the application
limitations shown in Table 6, "Ratings & Physical / Electrical Data"

The supply air temperature cannot exceed the “Maximum Supply
Air Temperature” specified in these instructions and on the fur­nace rating plate. Under NO circumstances can the furnace be
allowed to operate above the Maximum Supply Air Temperature.
Operating the furnace above the Maximum Supply Air Temperature
will cause premature heat exchanger failure, high levels of Carbon
Monoxide, a fire hazard, personal injury, property damage, and/or
death.

After about 5 minutes of operation, determine the furnace temperature
rise. Take temperature readings of both the return air and the heated air
in the ducts about six feet away from the furnace, where they will not be
affected by radiant heat. Increase or decrease the temperature rise by
changing the ATR jumper on the furnace control board. The jumper is
factory-set to deliver an air temperature rise near the midpoint of the
nameplate temperature rise range. If more air is desired (lower temper­ature rise), move the jumper to the -10 position. If less air is desired
(higher temperature rise), move the jumper to the +10 position.

Do not move the motor wires to different positions on the
furnace control board!

Johnson Controls Unitary Products 23

368261-UIM-A-0508

ADJUSTMENT OF FAN CONTROL SETTINGS

Cooling - The airflow delivered by the furnace during cooling operation
can be adjusted to match the cooling capacity of the A/C condensing
unit. This is done by moving the COOL jumper on the control board to
give the desired airflow.

Do not move the motor wires to different positions on the
furnace control board!

The jumper has four positions, which will deliver sufficient airflow in
cooling mode for the cooling capacities shown in the table below. The
CFM delivery on each jumper position is shown in Table13.

TABLE 13:

Cooling Airflow - A/C Capacity in Tons

Models

ABCD

Jumper Position

60/1200 3 2-1/2 2 1-1/2
80/1200 3 2-1/2 2 1-1/2

80/1600 4 3-1/2 3 2-1/2
100/1600 4 3-1/2 3 2-1/2
100/2000 5 4 3-1/2 3
120/2000 5 4 3-1/2 3

HUMIDIFIER
TERMINALS

BLUE

120VAC 120VAC

BLACK

XFORMER

BLOWER

NEUTRAL

NEUTRAL

BLOWER

WHITE

XFORMER

GROUND

BLOWER

BLOWER

YELLOW

RED

BLOWER

HOT

HUMIDIFIER

NEUTRAL

Continuous Fan Operation - The airflow delivered by the furnace dur­ing continuous fan operation can be adjusted as desired. This is done
my moving the FAN jumper on the control board to give the desired air­flow.

Do not move the motor wires to different positions on the
furnace control board!

The jumper has three positions. The "A" position delivers maximum air­flow, 100% of the blower capacity. Position "B" delivers approximately
70% of the blower capacity. And Position "C" delivers minimum airflow,
approximately 40% of the blower capacity.

HOT

INDUCER

NEUTRAL

IGNITER

HOT

NEUTRAL

EAC
TERMINALS

FLAME ROD

HOT

EAC

EAC

NEUTRAL

ZONE

CONTROL

ZONING
JUMPER

FLAME VOLTAGE

EXT

YES

NO

PRESSURE

SENSOR

HEAT PUMP
JUMPER

24VAC

MODULATE COIL

GAS VALVE

PRIMARY
LIMIT

AUX
LIMIT

AIR

DIAGNOSTIC
LIGHT

TEMP

SW

SENSOR

LOW
VOLTAGE
TERMINALS

FIGURE 30: Furnace Control Board

SECTION IX: SAFETY CONTROLS

CONTROL CIRCUIT FUSE

A 3-amp fuse is provided on the control circuit board to pr otect the 24­volt transformer from overload caused by control circuit wiring errors.
This is an ATO 3, automotive type fuse and is located on the control
board.

BLOWER DOOR SAFETY SWITCH

This unit is equipped with an electrical interlock switch mounted in the
burner compartment. This switch interrupts all power at the unit when
the panel covering the blower compartment is removed.

Electrical supply to this unit is dependent upon the panel that covers the
blower compartment being in place and properly positioned.

A-COIL

TEMP

H

MH

COOL

ML
L

LMH

CONT FAN

ATR

C

G

LAST ERROR
BUTTON

SENSOR

COOLING
SPEED
JUMPER

CONTINUOUS

+10F

FAN SPEED

NOM

-10F

JUMPER

TEST

TEST

BUTTON

BUTTON

ERROR

BUTTON

LO COMP

HI COMP

ID PLUG

Y1

O

DHUM

HUMIDISTAT
JUMPER

HUMIDISTAT

Y/Y2

W

HEAT PUMP

YES NO

YES NO

R

Main power to the unit must still be interrupted at the main power
disconnect switch before any service or repair work is to be done to
the unit. Do not rely upon the interlock switch as a main power dis­connect.
Blower and burner must never be operated without the blower
panel in place.

ROLLOUT SWITCH CONTROLS

These controls are mounted on the burner assembly. If the temperature
in the burner area exceeds its set point, the ignition control and the gas
valve are de-energized. The operation of this control indicates a mal­function in the combustion air blower, heat exchanger or a blocked vent
pipe connection. Corrective action is required. These are manual reset
controls that must be reset before operation can continue.

24 Johnson Controls Unitary Products

368261-UIM-A-0508

PRESSURE CONTROLS

Pressure Sensor - This furnace is equipped with a pressure sensor in
the burner compartment near the combustion blower. This sensor mon­itors combustion airflow through furnace and piping systems. If any of
the conditions listed below are detected by the pressure sensor, the
control board will prevent a hazardous condition from occurring by
speeding up the combustion blower motor in order to maintain ade­quate combustion airflow. If the combustion blower is already turning at
full speed, the furnace control will then start reducing the input to the
furnace in order to maintain proper combustion with the amount of com­bustion airflow available. If there is not enough combustion air available
to give proper combustion even at the minimum input rate (50%), the
control will close the gas valve and shut off the burners. The sensor will
detect the following conditions.

1. Blockage of vent piping or vent terminal

2. Failure of combustion air blower motor or blower wheel.
Pressure Switch - This furnace is equipped with a pressure switch

mounted on the furnace vestibule panel. This switch monitors the flow
through the vent system. The switch will close at the beginning of each
cycle when adequate combustion airflow is established. However, this
switch may be open under certain conditions when the burners are lit.
The pressure sensor is the primary flow sensor.

LIMIT CONTROLS

Limit Switch - This furnace is equipped with a high temperature limit
control mounted to the left side of the furnace vestibule panel. This limit
switch will open and shut off gas to the burners if it detects excessive air
temperature in the furnace, which can be caused by any of the following
conditions:

1. Dirty filter

2. Failure of the circulating blower motor or wheel

3. Too many supply or return registers closed or blocked.
Temperature Sensor - This furnace is also equipped with a tempera-

ture sensor mounted to the left side of the vestibule panel, near the limit
switch. This sensor monitors the temperature of the air being supplied
to the home. If the sensor detects air temperature higher than normal,
the furnace control will first speed up the circulating blower motor in
order to try to increase the amount of airflow being delivered, thereby
reducing the air temperature. If the blower motor is already turning at
full speed, the control will then start reducing the input to the furnace to
try to reduce the air temperature. If the supply air temperature is too
high even at the minimum input rate (50%), the control will close the
gas valve and shut off the furnace.

SECTION X: NORMAL OPERATION AND
DIAGNOSTICS

NORMAL OPERATION SEQUENCE

The furnace control calculates the optimum firing rate each time the
wall thermostat R and W contacts close or open (at the beginning and
at the end of each call for heat) based on information from the thermo­stat and past demand. UNLIKE CONVENTIONAL SYSTEMS, THE
WALL THERMOSTAT DOES NOT SIMPLY TURN THE FURNACE ON
AND OFF. THE FURNACE CONTROL CALCULATES THE DEMAND
AND MAY CONTINUE TO FIRE THE FURNACE DURING PORTIONS
OF THE THERMOSTAT "OFF" CYCLE.

When the wall thermostat R and W contacts close, indicating a call for
heat, the following sequence occurs:

1. The inducer is energized and ramps up its speed until airflow is
proven by the pressure switch and by the pressure sensor on the
control board.

2. The hot surface ignitor is energized.

3. After a 17-20 second igniter heatup, the gas valve opens and the
burners light.

4. When the control senses that flame is present, the circulating

blower starts at low speed.

5. The furnace fires at 70% of full rate for 30-45 seconds, then drops
to the minimum (50%) firing rate.

6. The firing rate is automatically adjusted to meet demand, increas­ing gradually to maximum (100%) firing rate if the thermostat is not
satisfied within a defined time.

7. When the thermostat R and W contacts open (thermostat is satis­fied) the furnace control recalculates the demand and a new firing
rate.

A. If demand exceeds the minimum firing rate, the burners will

continue to fire at a recalculated reduced firing rate, decreas­ing if the thermostat remains off for a defined time.

b. If demand does not exceed the minimum firing rate, the burn-

ers will shut off immediately.

8. After the burners shut off, the circulating blower will continue to run
until the temperature sensor detects that the supply air tempera­ture has dropped to the desired level, which should take from 30 to
90 seconds.

FURNACE CONTROL DIAGNOSTICS

This furnace has built-in self-diagnostic capability. If a system problem
occurs, a flashing LED shows a fault code. The LED can flash red,
green or amber to indicate various conditions. The LED is located on
the furnace control board and can be seen through the clear view port
in the lower door of the furnace. To indicate an error condition, the LED
will turn on for 1/4 second and off for 1/4 second. The pattern will be
repeated the number of times equal to the flash code. For instance, a
"six flash code" will be indicated by the LED turning on and off six times.
There will be a two second off period between each set of flashes. The
flash codes and an indication of their likely causes are listed below:

STEADY OFF - No 24V power to board. Check the 24 volt control cir­cuit fuse on the board. Check the circuit breaker or fuse on the 115 volt
supply power to the furnace. Check that the 24 volt transformer.

One Green Flash - Normal Operation with no call for heat.
Two Green Flashes - Indicator for "No error codes in memory". See

Diagnostic Fault Code Storage and Retrieval section below.
Three Green Flashes - Indicator for "Error codes cleared from mem-

ory". See Diagnostic Fault Code Storage and Retrieval section below.
Rapid Green Flash - Control is in "Factory Speedup" mode. This mode

is used only during factory run-testing of the furnace. To stop this mode,
cycle power to the furnace off and then back on.

One Amber Flash - Normal operation with call for cooling.
Two Amber Flashes - Normal operation with call for heat.
Three Amber flashes - Normal operation, burner is on at end of heat-

ing cycle after wall thermostat has been satisfied.
Four Amber Flashes - Heating capacity is reduced due to restriction in

the circulating air system. Check for dirty filter or closed registers.
Five Amber Flashes - Heating capacity is reduced due to restriction in

the combustion air or vent system. Check for blocked vent/air pipe or
clogged condensate drain. Above 4,000 feet altitude, this may also indi­cate automatic, normal derating for altitude. See page 7 for additional
high altitude information.

Six Amber Flashes - (Heat Pump applications only) Normal operation
with call for heat pump heating.

Rapid Amber Flash - Low flame sense current. Check for dirty or mis­located flame sensor rod.

One Red Flash - Flame is present with no power being supplied to gas
valve. This can be caused by a gas valve that is slow to close or that
leaks gas through to the burners.

Two Red Flashes - Stuck closed pressure switch. The con trol conf irm s
that the pressure switch contacts are open at the beginning of each
cycle. This could be caused by a faulty pressure switch or by mis-wiring
of the pressure switch.

Johnson Controls Unitary Products 25

368261-UIM-A-0508

Three Red Flashes - Stuck open pressure switch. This indicates that
the pressure switch is open when it should be closed. This could be
caused by a faulty combustion air blower, blocked vent pipe, blocked air
intake pipe, blocked condensate drain, faulty pressure switch hose or a
faulty pressure switch.

Four Red Flashes - High limit switch open or 24 volt fuse is open. This
may be caused by a dirty air filter, improperly sized duct system, faulty
blower motor, restricted circulating airflow or an open fuse on the con­trol board.

Five Red Flashes - Rollout switch or auxiliary limit switch open. Check
the rollout switch on the side of the burner box. It is a manual reset
switch. To reset, push the small button in the center of the switch. If it
cannot be reset or if the switch trips again, contact a qualified service­man. Check the limit switch mounted in the combustion air blower hous­ing.

Six Red Flashes - Current failure on modulating gas valve.
Seven Red Flashes - Lockout due to no ignition. The control will try

three times for ignition. If flame cannot be established in three tries, the
control will lockout for one hour and then will try again to light. Check
gas supply, ignitor, gas valve, flame sensor.

Eight Red Flashes - Lockout due to too many flame recycles. This
flash code occurs if flame is lost five times during a single heating cycle.
This could be caused by a faulty gas valve, low gas pressure, or dirty
flame sensor. The control will lock out for one hour and then will try
again.

Nine Red Flashes - Reversed line polarity or improper grounding.
Check polarity of the incoming power to the furnace. Check the ground­ing of the furnace, including the transformer ground and the L1 and
neutral connections.

Ten Red Flashes - Gas valve circuit shorted. Check gas valve wiring. If
correct, replace gas valve.

Eleven Red Flashes - Main blower failure - This flash code occurs
when the main limit opens and fails to reclose within five minutes, indi­cating that the blower motor or blower wheel has failed.

Twelve Red Flashes - ID plug is not present or not connected properly,
check for loose plug or loose wires in plug.

Steady On Red - Control fault has been detected or there is 24 volts
present without 115 volts. Check that there is 24 volts and 115 volts
being supplied to the board. If so, then the board should be replaced.

IGNITION CONTROL FLAME SENSE LEVELS

Normal flame sense current is approximately

3.7 microamps DC (µa)

Low flame signal warning starts at 1.5 microamps.

Low flame signal control lockout point is

0.1 microamps DC (µa)

DIAGNOSTIC FAULT CODE STORAGE AND
RETRIEVAL

The control in this furnace is equipped with memory that will store up to
five error codes to allow a service technician to diagnose problems
more easily. This memory will be retained even if power to the furnace
is lost. Only a qualified service technician should use this feature.

The control stores up to five separate error codes. If more than five
error codes have occurred since the last reset, only the five most recent
will be retained. The furnace control board has a button, labeled "LAST
ERROR" that is used to retrieve error codes. This function will only
work if there are no active thermostat signals. So any call for heating,
cooling or continuous fan must be terminated before attempting to
retrieve error codes.

T o retrieve the error codes, push the LAST ERROR button. The LED on
the control will then flash the error codes that are in memory, starting
with the most recent. There will be a two-second pause between each
flash code. After the error codes have all been displayed, the LED will
resume the normal slow green flash after a five second pause. To
repeat the series of error codes, push the button again.

If there are no error codes in memory, the LED will flash two green
flashes. T o clear the memory , push the LAST ERROR button and hold it
for more than five seconds. The LED will flash three green flashes
when the memory has been cleared, then will resume the normal slow
green flash after a five-second pause.

26 Johnson Controls Unitary Products

SECTION XI: REPLACEMENT PARTS LIST

DESCRIPTION

MOTOR

MOTOR, DIRECT DRIVE BLOWER
BLOWER, COMBUSTION

ELECTRICAL

CAPACITOR, RUN
SWITCH, LIMIT
CONTROL, FURNACE

IGNITER
SENSOR, FLAME
SWITCH, PRESSURE
SWITCH, DOOR

TRANSFORMER
VALVE, GAS
CONTROL, TEMPERATURE
SENSOR, PRESSURE
SENSOR, THERMISTOR

AIR MOVING

HOUSING, BLOWER
WHEEL, BLOWER

FABRICATED PARTS

BAFFLE, FLUE
BURNER, MAIN GAS
BRACKET, IGNITER
SHELF, BLOWER
RAIL, BLOWER (2 Req’d)

368261-UIM-A-0508

DESCRIPTION

FABRICATED PARTS Continued

BRACKET, BLOWER TRACK (2 Req’d)
HEAT EXCHANGER ASS’Y
MANIFOLD, GAS
PAN, BOTTOM
PANEL, TOP
PANEL, DOOR (2 Req’d)

VENT PAN, COMBUSTION (w/Gasket)
PANEL, BLOCKOFF

LO-NOX SCREEN (L-Models Only)

MISCELLANEOUS

ORIFICE, BURNER (Natural #45)
SIGHT GLASS, OVAL (2 Req’d)
GASKET, FOAM (Door) (1.5 ft req’d)
GASKET, INTAKE PAN
PLUG, VENT HOLE
BRACKET, DOOR
WIRING HARNESS
FERRULE (3 Req’d)
GROMMET (3 Req’d)

MOTOR MOUNT

HOSE ASSY, VACUUM
PLUG, ID (Control Board)
KNOB, QUARTER TURN (4 Req’d)
UNION
DIAGRAM, WIRING

REPLACEMENT PART CONTACT INFORMATION

This is a generic parts list. To request a complete parts list, refer to the contact information below:

• Visit our website at www.source1parts.com for the following information:

1. Search for a part or browse the catalog.

2. Find a dealer or distributor.

3. Customer Service contact information.
a. Click on the “Brand Links” button

b. Click on the “Customer Service” button

• You can contact us by mail. Just send a written request to:

Johnson Controls Unitary Products

Consumer Relations

5005 York Drive

Norman, OK 73069

Johnson Controls Unitary Products 27

SECTION XII: WIRING DIAGRAM

FIGURE 31: Wiring Diagram
Subject to change without notice. Printed in U.S.A. 368261-UIM-A-0508

Copyright © 2008 by Johnson Controls, Inc. All rights reserved. Supersedes: Nothing

Johnson Controls Unitary Products

5005 York Drive

Norman, OK 73069