Lennox SL280135V60D, SL280UH090V48B, SL280UH110V60C, SL280UH060NV36A, SL280UH100NV60C Installation Instructions Manual

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Dallas, Texas USA

INSTALLATION INSTRUCTIONS SL280UHV

507337-01 04/2017 Supersedes 05/2016

THIS MANUAL MUST BE LEFT WITH THE

HOMEOWNER FOR FUTURE REFERENCE

This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to the potential for personal injury or death.

CAUTION

As with any mechanical equipment, contact with sharp sheet metal edges can result in personal injury. Take care while handling this equipment and wear gloves and protective clothing.

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a licensed professional HVAC installer or equivalent, service agency, or the gas supplier.

Table of Contents

Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Parts Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

SL280UHV Gas Furnace . . . . . . . . . . . . . . . . . . . . . . . . . 4

Shipping and Packing List . . . . . . . . . . . . . . . . . . . . . . . . 4

Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Use of Furnace as a Construction Heater . . . . . . . . . . . 5

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Combustion, Dilution & Ventilation Air . . . . . . . . . . . . . . 6

Setting Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Duct System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

NOTICE

A thermostat is not included and must be ordered separately.

• The Lennox icomfort Wi-Fi® thermostat must be used

in communicating applications.

• In non-communicating applications, the Lennox

ComfortSense® 7500 thermostat may be used, as well as other non-communicating thermostats.

In all cases, setup is critical to ensure proper system operation.

Field wiring for both communicating and noncommunicating applications is illustrated in diagrams, which begin on Page 25.

Integrated Control Settings . . . . . . . . . . . . . . . . . . . . . . . 33

Blower Performance Data . . . . . . . . . . . . . . . . . . . . . . . . 36

Unit Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Gas Pressure Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 42

Proper Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

High Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Other Unit Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Heating Sequence of Operation . . . . . . . . . . . . . . . . . . . 44

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Repair Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Integrated Control Diagnostic Codes . . . . . . . . . . . . . . . 49

Program Unit Capacity/Size Mode . . . . . . . . . . . . . . . . . 55

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Page 1

Unit Dimensions - inches (mm)

(19)

FRONT VIEW SIDE VIEW

NOTE - 60C and 60D size units that require second stage

air volumes over 1800 cfm (850 L/s) must have one of the following:

1. Single side return air with transition, to accommodate 20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter. Required to maintain proper air velocity.

2. Single side return air with optional Return Air Base

3. Bottom return air.

4. Return air from both sides.

5. Bottom and

one side return air.

See Blower Performance Ta bles for additional information.

Flue outlet may be horizontal but furnace must be vented vertically

Optional External Side Return Air Filter Kit is not for use

with the optional Return Air Base.

9/16 (14)

OPTIONAL

EXTERNAL

SIDE RETURN

AIR FILTER KIT

(Either Side)

(838)

FLUE OUTLET

(Top)

OPTIONAL

EXTERNAL

SIDE RETURN

AIR FILTER KIT

(Either Side)

1-1/2 (38)

Front Panel

3 (76) Right 7 (178) Left

9-1/8 (232) Right

8-5/8 (219) Left

5-3/8 (137) Right

2-3/16 (56) Left

3-1/8 (79)

TOP VIEW

3-1/4 (83)

FLUE OUTLET

(Either Side)

GAS PIPING INLET

(Either Side)

ELECTRICAL INLET

(Either Side)

SUPPLY AIR

OPENING

23-3/4

(603)

(635)

27-3/4

(705)

19-7/16

(494)

9/16

(14)

14-3/4

(375)

(406)

AIR FLOW

5/8

3/4

Model No.

SL280UH070V36A 14 368 13-3/8 340 13 330 4-3/4 121 SL280UH090V36B

SL280UH090V48B SL280UH09060C SL280UH110V60C SL280135V60D 24-1/2 622 23-3/8 546 23 584 9-3/4 248

Bottom Return

Air Opening

17-1/2 446 16-3/8 416 16 406 6-1/4 159

in. mm in mm in mm in mm

A B C D

21 533 19-7/8 504 19-1/2 495 8 203

3/4

(19)

(16)

3-1/4

(83)

(584)

Side Return Air Opening (Either Side)

23-1/2

(597)

Bottom Return

Air Opening

(356)

1-15/16 (49)

Page 2

1-1/2

(38)

Parts Arrangement

COMBUSTION AIR INDUCER

PRESSURE SWITCH

HEAT EXCHANGER

BURNER BOX

INNER BLOWER ACCESS PANEL

GAS VALV E

ACCESS PANEL

SIGHT GLASS

CABINET

CONTROL BOX

(Includes two-stage integrated control,

transformer and circuit breaker)

BLOWER

ASSEMBLY

FIGURE 1

Page 3

SL280UHV Gas Furnace

The SL280UHV gas furnace is equipped with a two-stage, variable speed integrated control. the control is compatible with:

Communicating thermostats - icomfort Wi-Fi®. Non-comunicating thermostats - ComfortSense or other

conventional thermostats. Control systems - Harmony III™ Zone Control System

(non-communicating). Each SL280UHV unit is shipped ready for installation in

the upow or horizontal position (left or right). The furnace

is shipped with the bottom panel in place. The bottom panel must be removed if the unit is to be installed in a horizontal application. The panel may also be removed in

upow applications.

Shipping and Packing List

Package 1 of 1 contains

1 - Assembled SL280UHV unit 1 - Bag assembly containing the following: 2 - Screws 1 - Snap bushing 1 - Snap plug 1 - Wire tie 1 -Vent warning label 1 - Owner’s manual and warranty card

The following items may be ordered separately:

1 - Thermostat 1 -Suspension Kit (for horizontal installations) 1 - Propane/LP changeover kit 1 - Return air base 1 - High altitude kit

1 - Side lter kit

Check equipment for shipping damage. If you nd any

damage, immediately contact the last carrier.

Safety Information

WARNING

Danger of explosion. There are circumstances in which odorant

used with LP/propane gas can lose its scent. In case of a leak, LP/propane gas will settle

close to the oor and may be difcult to

smell. An LP/propane leak detector should be installed in all LP applications.

WARNING

CAUTION

As with any mechanical equipment, contact with sharp sheet metal edges can result in personal injury. Take care while handling this equipment and wear gloves and protective clothing.

Certications

SL280UHV units are CSA International certied to ANSI

Z21.47. In the USA, installation of gas furnaces must conform with

local building codes. In the absence of local codes, units must be installed according to the current National Fuel Gas Code (ANSI-Z223.1). The National Fuel Gas Code is available from the following address:

American National Standards Institute, Inc. 11 West 42nd Street New York, NY 10036

Clearances

Adequate clearance must be made around the air openings into the vestibule area. In order to ensure proper unit operation, combustion and ventilation air supply must be provided according to the current National Fuel Gas Code.

Vent installations must be consistent with the venting tables (in this instruction) and applicable provisions of local building codes.

This furnace is CSA International certied for installation

clearances to combustible material as listed on the unit nameplate and in the tables in gures 7 and 11. Accessibility and service clearances must take precedence over

re protection clearances.

NOTE - For installation on combustible oors, the furnace shall not be installed directly on carpeting, tile, or other combustible material other than wood ooring.

Installed Locations

For installation in a residential garage, the furnace must be installed so that the burner(s) and the ignition source are located no less than 18 inches (457 mm) above the

oor. The furnace must be located or protected to avoid

physical damage by vehicles. When a furnace is installed in a public garage, hangar, or other building that has a hazardous atmosphere, the furnace must be installed according to recommended good practice requirements and current National Fuel Gas Code.

Temperature Rise

NOTE - Furnace must be adjusted to obtain a temperature rise(high and low re) within the range(s) specied on the unit nameplate. Failure to do so may cause erratic limit operation and may result in premature heat exchanger failure.

This SL280UHV furnace must be installed so that its electrical components are protected from water.

Page 4

Installed in Combination with a Cooling Coil

When this furnace is used with cooling units, it shall be installed in parallel with, or on the upstream side of, cooling units to avoid condensation in the heating compartment.

See gure 1. With a parallel ow arrangement, a damper (or other means to control the ow of air) must adequately

prevent chilled air from entering the furnace. If the damper is manually operated, it must be equipped to prevent operation of either the heating or the cooling unit, unless it is

in the full HEAT or COOL setting. See gure 1.

Heating Unit Installed Parallell to Air Handler Unit

Dampers

(open during heating operation only)

Gas Unit

Air Handler Unit

Dampers

(open during cooling operation only)

Heating Unit Installed Upstream of Cooling Unit

Gas Unit

Evaporator

FIGURE 2

When installed, this furnace must be electrically grounded according to local codes. In addition, in the United States, installation must conform with the current National Electric Code, ANSI/NFPA No. 70. The National Electric Code (ANSI/NFPA No. 70) is available from the following address:

National Fire Protection Association 1 Battery March Park Quincy, MA 02269 NOTE - This furnace is designed for a minimum contin-

uous return air temperature of 60°F (16°C) or an intermittent operation down to 55°F (13°C) dry bulb for cases where a night setback thermostat is used. Return air temperature must not exceed 85°F (29°C) dry bulb.

The SL280UHV furnace may be installed in alcoves, closets, attics, basements, garages, and utility rooms in the

upow or horizontal position.

This furnace is not designed for installation in mobile homes, recreational vehicles, or outdoors.

Never use an open ame to test for gas leaks. Check all

connections using a commercially available soap solution

made specically for leak detection.

operation of the unit with clogged or misplaced lters will

damage the unit. SL280UHV units may be used for heating of buildings or

structures under construction, if the following conditions are met:

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

• A room thermostat must control the furnace. The use of

xed jumpers that will provide continuous heating is not

allowed.

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

• Return air temperature range between 60°F (16°C) and 80°F (27°C) must be maintained.

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

• Air lters must be replaced upon construction comple- tion.

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

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

conned space with air from outside.

• The furnace heat exchanger, components, duct sys-

tem, air lters and evaporator coils must be thoroughly cleaned following nal construction clean-up.

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

General

These instructions are intended as a general guide and do not supersede local codes in any way. Consult authorities having jurisdiction before installation.

In addition to the requirements outlined previously, the following general recommendations must be considered when installing a SL280UHV furnace:

• Place the furnace as close to the center of the air distribution system as possible. The furnace should also be located close to the chimney or vent termination point.

• Do not install the furnace where drafts might blow directly into it. This could cause improper combustion and unsafe operation.

Use of Furnace as Construction Heater

Lennox does not recommend the use of SL280UHV units as a construction heater during any phase of construction. Very low return air temperatures, harmful vapors and

Page 5

• Do not block the furnace combustion air openings with clothing, boxes, doors, etc. Air is needed for proper combustion and safe unit operation.

• When the furnace is installed in an attic or other insulated space, keep insulation away from the furnace.

• Please consult the manufacturer of your evaporator coil for their recommendations on distance required between the heat exchanger and their drain pan. Adequate space must be provided between the drain pan and the furnace heat exchanger.

NOTE - The Commonwealth of Massachusetts stipulates these additional requirements:

• Gas furnaces shall be installed by a licensed plumber

or tter only.

• The gas cock must be “T handle” type.

• When a furnace is installed in an attic, the passageway

to and service area surrounding the equipment shall

be oored.

WARNING

This prodcut contains a chemical known to the State of California to cause cancer, birth defects, or other reproductive harm.

Combustion, Dilution & Ventilation Air

In the past, there was no problem in bringing in sufcient outdoor air for combustion. Inltration provided all the air

that was needed. In today’s homes, tight construction practices make it necessary to bring in air from outside for combustion. Take into account that exhaust fans, appli-

ance vents, chimneys, and replaces force additional air

that could be used for combustion out of the house. Unless outside air is brought into the house for combustion, negative pressure (outside pressure is greater than inside pressure) will build to the point that a downdraft can occur in the furnace vent pipe or chimney. As a result, combustion gases enter the living space creating a potentially dangerous situation.

In the absence of local codes concerning air for combustion and ventilation, use the guidelines and procedures in

this section to install SL280UHV furnaces to ensure efcient and safe operation. You must consider combustion air needs and requirements for exhaust vents and gas piping. A portion of this information has been reprinted

with permission from the National Fuel Gas Code (ANSI‐

Z223.1). This reprinted material is not the complete and

ofcial position of the ANSI on the referenced subject,

which is represented only by the standard in its entirety.

CAUTION

Do not install the furnace in a corrosive or contaminated atmosphere. Meet all combustion and ventilation air

requirements, as well as all local codes.

CAUTION

Insufcient combustion air can cause headaches,

nausea, dizziness or asphyxiation. It will also cause excess water in the heat exchanger resulting in rusting

and premature heat exchanger failure. Excessive exposure to contaminated combustion air will result in safety and performance related problems. Avoid exposure to the following substances in the combustion air supply:

Permanent wave solutions Chlorinated waxes and cleaners Chlorine base 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 ermanent waves

All gas-red appliances require air for the combustion process. If sufcient combustion air is not available, the furnace or other appliances will operate inefciently and

unsafely. Enough air must be provided to meet the needs of all fuel-burning appliances and appliances such as exhaust fans which force air out of the house. When replaces, exhaust fans, or clothes dryers are used at the same time as the furnace, much more air is necessary to ensure proper combustion and to prevent a downdraft.

Insufcient air causes incomplete combustion which can

result in carbon monoxide. In addition to providing combustion air, fresh outdoor air

dilutes contaminants in the indoor air. These contaminants may include bleaches, adhesives, detergents, solvents

and other contaminants which can corrode furnace components.

The requirements for providing air for combustion and ventilation depend largely on whether the furnace is in-

stalled in an unconned or a conned space.

Page 6

Unconned Space

EQUIPMENT IN CONFINED

SPACE ALL AIR FROM INSIDE

CHIMNEY

OR GAS

VENT

FURNACE

WATER

HEATER

OPENINGS

(To Adjacent

Room)

NOTE - Each opening shall have a free area of at least one square inch (645 mm

ing of all equipment in the enclosure, but not less than 100 square inches (64516 mm

AIR FLOW

An unconned space is an area such as a basement or

large equipment room with a volume greater than 50 cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that space. This space also includes adjacent rooms which are not separated by a door. Though an area may appear to be

unconned, it might be necessary to bring in outdoor air

for combustion if the structure does not provide enough air

by inltration. If the furnace is located in a building of tight

construction with weather stripping and caulking around the windows and doors, follow the procedures in the air from outside section.

Conned Space

A conned space is an area with a volume less than 50

cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that

space. This denition includes furnace closets or small

equipment rooms. When the furnace is installed so that supply ducts carry

air circulated by the furnace to areas outside the space containing the furnace, the return air must be handled by ducts which are sealed to the furnace casing and which terminate outside the space containing the furnace. This is especially important when the furnace is mounted on

a platform in a conned space such as a closet or small

equipment room. Even a small leak around the base of the unit at the platform or at the return air duct connection can cause a potentially dangerous negative pressure condition. Air for combustion and ventilation can be brought

into the conned space either from inside the building or

from outside.

Air from Inside

If the conned space that houses the furnace adjoins a space categorized as unconned, air can be brought in by

providing two permanent openings between the two spaces. Each opening must have a minimum free area of 1 square inch (645 mm2) per 1,000 Btu (.29 kW) per hour of

total input rating of all gas-red equipment in the conned

space. Each opening must be at least 100 square inches (64516 mm2). One opening shall be within 12 inches (305 mm) of the top of the enclosure and one opening within 12

inches (305 mm) of the bottom. See gure 3.

Air from Outside If air from outside is brought in for combustion and ventila-

tion, the conned space must have two permanent openings. One opening shall be within 12 inches (305 mm) of the top of the enclosure and one opening within 12 inches (305 mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors or indirectly through vertical ducts. Each opening shall have a minimum free area of 1 square inch (645 mm2) per 4,000 Btu (1.17 kW) per hour of total input rating of all equipment in the enclosure. See gures 4 and 5. When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 square inch (645 mm2) per 2,000 Btu (.56 kW) per total input rating of

all equipment in the enclosure. See gure 6.

When ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect. The minimum dimension of rectangular air ducts shall be no less than 3 inches (75 mm). In calculating free

area, the blocking effect of louvers, grilles, or screens must be considered. If the design and free area of protective covering is not known for calculating the size opening required, it may be assumed that wood louvers will have 20 to 25 percent free area and metal louvers and grilles will have 60 to 75 percent free area. Louvers and grilles

must be xed in the open position or interlocked with the

equipment so that they are opened automatically during equipment operation.

FIGURE 3

Page 7

other equipment in the enclosure.

CHIMNEY OR

GAS VENT

FURNACE

(Inlet Air from Crawlspace and Outlet Air to Ventilated Attic)

VENTILATION LOUVERS

(Each end of attic)

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

OUTLET

AIR

WATER

HEATER

CHIMNEY

OR GAS

VENT

FURNACE

VENTILATION

LOUVERS

(For unheated crawl space)

AIR FLOW

NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch (645

) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.

INLET

AIR

FIGURE 4

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

(All Air Through Ventilated Attic)

CHIMNEY

OR GAS

VENT

OUTLET

AIR

VENTILATION LOUVERS

(Each end of attic)

INLET AIR

(Ends 12 in.

above bottom)

FURNACE

WATER

HEATER

EQUIPMENT IN

CONFINED SPACE

ALL AIR FROM

OUTSIDE

OUTLET AIR

AIR FLOW

NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch (645 mm

ment in the enclosure.

FIGURE 5

WATER

HEATER

) per 4,000

Page 8

AIR FLOW

NOTE - Each air duct opening shall have a free area of at least one square inch (645 mm

) per 2,000 Btu (.59 kW) per hour of

INLET AIR

the total input rating of all equipment in the enclosure. If the equipment room is located against an outside wall and the air openings ing shall have a free area of at least one square inch (645 mm per 4,000 Btu (1.17 kW) per hour of the total input rating of all

FIGURE 6

)

Setting Equipment

WARNING

Do not install the furnace on its front or its back. Do not connect the return air ducts to the back of the furnace. Doing so will adversely affect the operation of the safety control devices, which could result in personal injury or death.

.The SL280UHV gas furnace can be installed as shipped

in either the upow position or the horizontal position.

Select a location that allows for the required clearances that are listed on the unit nameplate. Also consider gas supply connections, electrical supply, vent connection, and installation and service clearances [24 inches (610 mm) at unit front]. The unit must be level.

NOTE - Units with 1/2 hp blower motors are equipped with three exible legs and one rigid leg. See gure 7. The rigid leg is equipped with a shipping bolt and a at white plastic washer (rather than the rubber mounting grommet used with a exible mounting leg). The bolt and washer must

be removed before the furnace is placed into operation. After the bolt and washer have been removed, the

rigid leg will not touch the blower housing.

SL280UHV07036A and

SL280UHV09036B WITH 1/2 HP

BLOWER MOTOR

RIGID LEG

remove shipping bolt and washer

Upow Applications

Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or

alcove installations are shown in gure 8.

Upflow Application Installation Clearances

Top

Left Side

AIR FLOW

Bottom

Type of Vent

Connector

Top 1 in. (25 mm) 1 in. (25 mm)

*Front 2-1/4 in. (57 mm)** 2-1/4 in. (57 mm)

Back 0 0

Sides 0† 0

Vent 6 in. (152 mm) 1 in. (25 mm)

Floor 0‡ 0‡

*Front clearance in alcove installation must be 24 in. (610 mm). Maintain a minimum of 24 in. (610 mm) for front service access. ** 3-1/4 in. if single wall vent pipe is used. ‡For installation on a combustible floor, do not install the furnace directly on carpeting, tile or other combustible materials other than wood flooring. †Left side requires 3 inches if a single wall vent is used on 14-1/2 inch nets.

Type C Type B1

Right Side

FIGURE 7

FIGURE 8

Page 9

Return Air -- Upow Applications

Transition

Return air can be brought in through the bottom or either

side of the furnace installed in an upow application. If the

furnace is installed on a platform with bottom return, make an airtight seal between the bottom of the furnace and the platform to ensure that the furnace operates properly and safely. The furnace is equipped with a removable bottom panel to facilitate installation.

Markings are provided on both sides of the furnace cabinet for installations that require side return air. Cut the furnace cabinet at the maximum dimensions shown on page 2.

NOTE - 60C and 60D units that require air volumes over 1800 cfm (850 L/s) must have one of the following:

1 - Return air from single side with transition which

willaccommodate 20 x 25 x 1 in. (508 x 635 x 25

mm) cleanable air lter. (Required to maintain proper air velocity.See gure 9.

2 - Return air from single side with optional RAB

Return Air Base. See gure 10.

3 -Return air from bottom and one side. 4 -Return air from both sides. 5 -Return air from bottom.

Refer to Engineering Handbook for additional information.

Single Side Return Air

(with transition and filter)

20” X 25” X 1”

(508mm X635mm X 25mm)

Cleanable Filter

Return Air

Plenum

AIR FLOW

FIGURE 9

(Upflow Applications Only -- For use with A, B, C and D cabinets)

Optional Return Air Base

FURNACE

FRONT

IF BASE IS USED

WITHOUT

INDOOR AIR

AIR FLOW

14−1/2” (368) A Width (65W75)

17−1/2” (446) B Width (50W98)

21”− (533) C Width (50W99)

24−1/2”− (622) D Width (51W00)

NOTE- Optional Side Return Air Filter Kits are not for use with Optional Return Air Base.

Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet. Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in. (584 x 279 mm). The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown. Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air opening. The size of the opening must not extend beyond the markings on the furnace cabinet.

To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.

OPTIONAL

RETURN AIR BASE

IAQ CABINET,

A SINGLE

RETURN AIR

PLENUM

MUST

COVER BOTH

UNIT AND

RETURN

AIR BASE

OPENINGS

3−1/4

(83)

7−1/4 (184)

23 (584)

Overall

(Maximum)

Unit side return air

Opening

5−5/8 (143)

SIDE RETURN

AIR OPENINGS

(Either Side)

26−7/8

(683)

SIDE VIEW

(584)

Minimum

11 (279)

Maximum

14 (356)

22−7/16

(570)

Overall

(Maximum)

3/4

(19)

FIGURE 10

Page 10

Removing the Bottom Panel

Screw

Bottom Panel

Bottom Cap

Hori

zontal Application

Installation Clearances

Top

Bottom

Left End

Right End

AIR FLOW

Vent Connector

Type

Type C Type B1

Top 0 0

*Front 2-1/4 in. (57 mm)** 2-14 in. (57 mm)

Back 0 0

Ends 2 in. (51 mm) 2 in. (51 mm)

Vent 6 in. (152 mm) 1 in. (25 mm)

Floor 0‡ 0‡

*Front clearance in alcove installation must be 24 in. (610 mm). Maintain a minimum of 24 in. (610 mm) for front service access. ** 3-1/4 in. if single wall vent pipe is used. ‡For installations on a combustible floor, do not install the furnace directly on carpeting, tile or other combustible materials other than wood flooring.

Typical Horizontal Application

Unit Suspended in Attic or Crawlspace

Bracket

Bottom Cap

Metal Strap

3/16 inch

Air Flow

Remove the two screws that secure the bottom cap to the furnace. Pivot the bottom cap down to release the bottom panel. Once the bottom panel has been removed, reinstall

the bottom cap. See gure 11.

Horizontal Applications

The SL280UHV furnace can be installed in horizontal applications. Order kit number 51W10 (or use equivalent) from Lennox.

Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or

alcove installations are shown in gure 12.

This furnace may be installed in either an attic or a crawlspace. Either suspend the furnace from roof rafters or

oor joists, as shown in gure 13, or install the furnace on a platform, as shown in gure 14.

Figure 11

FIGURE 12

FIGURE 13

. NOTE - Heavy-gauge perforated sheet metal straps may be used to suspend the unit from roof rafters or ceiling joists. When straps are used to suspend the unit in this way, support must be provided for both the ends. The straps must not interfere with the plenum or exhaust piping installation. Cooling coils and supply and return air

plenums must be supported separately. NOTE - When the furnace is installed on a platform in a

crawlspace, it must be elevated enough to avoid water damage and to allow the evaporator coil to drain.

Return Air -- Horizontal Applications

Return air must be brought in through the end of a furnace installed in a horizontal application. The furnace is equipped with a removable bottom panel to facilitate in-

stallation. See gure 11.

CAUTION

If this unit is being installed in a space serviced by an exhaust fan, power exhaust fan, or other device which may create a negative pressure in the space, take care when sizing the inlet air opening. The inlet air opening must be sized to accommodate the maximum volume of exhausted air as well as the maximum volume of combustion air required for all gas appliances serviced by this space.

Page 11

Horizontal Application

Unit Installed on Platform

clearances.

GAS

ENTRY

VENT

PIPE

See the unit nameplate for

Line contact is permissible

SERVICE PLATFORM

Improper installation of the furnace can result in

personal injury or death. Combustion and ue products

must never be allowed to enter the return air system or the living space. Use screws and joint tape to seal the return air system to the furnace. In platform installations with bottom return air, the furnace should be sealed airtight to the return air plenum. A door must never be used as a portion of the return air duct system. The base must provide a stable support and an airtight seal to the furnace. Allow absolutely no sagging, cracks, gaps, etc. The return and supply air duct systems must never be connected to or from other heating devices such as a

replace or stove, etc. Fire, explosion, carbon monoxide

poisoning, personal injury and/or property damage could result.

The inner blower panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal injury or death.

Filters

This unit is not equipped with a lter or rack. A eld-provided high-velocity lter is required for the unit to operate properly. Table 1 lists recommended lter sizes.

A lter must be in place any time the unit is operating.

FIGURE 14

WARNING

If a highefciency lter is being installed as part of this system to ensure better indoor air quality, the lter must be properly sized. Highefciency lters have a higher static pressure drop than standardefciency glass/foam lters. If the pressure drop is too great, system capacity

and performance may be reduced. The pressure drop may also cause the limit to trip more frequently during the winter and the indoor coil to freeze in the summer, resulting in an increase in the number of service calls.

Before using any lter with this system, check the specications provided by the lter manufacturer against

the data given in the appropriate Lennox Product

Specications bulletin. Additional information is provided

in Service and Application Note ACC002 (August 2000).

TABLE 1

Furnace Cabinet

Width

14-1/2” 16 X 25 X 1 (1) 14 X 25 X 1 (1)

17-1/2” 16 X 25 X 1 (1) 16 X 25 X 1 (1)

21” 16 X 25 X 1 (1) 20 X 25 X 1 (1)

24-1/2” 16 X 25 X 1 (2) 24 X 25 X 1 (1)

Side Return Bottom Return

Duct System

Use industry-approved standards (such as those published by Air Conditioning Contractors of America or American Society of Heating, Refrigerating and Air Conditioning Engineers) to size and install the supply and return air duct system. This will result in a quiet and low-static system that has uniform air distribution.

NOTE - Do not operate the furnace in the heating mode with an external static pressure that exceeds 0.8 inche w.c. Higher external static pressures may cause erratic limit operation.

Supply Air Plenum

If the furnace is installed without a cooling coil, a removable access panel must be installed in the supply air duct. The access panel should be large enough to permit in-

spection (either by smoke or reected light) of the heat

exchanger for leaks after the furnace is installed. The furnace access panel must always be in place when the furnace is operating and it must not allow leaks into the supply air duct system.

Return Air Plenum NOTE - Return air must not be drawn from a room

where this furnace, or any other gas-fueled appliance (i.e., water heater), or carbon monoxide- producing

device (i.e., wood replace) is installed.

When return air is drawn from a room, a negative pressure is created in the room. If a gas appliance is operating in

a room with negative pressure, the ue products can be

pulled back down the vent pipe and into the room. This

Filter Size

Page 12

reverse ow of the ue gas may result in incomplete combustion and the formation of carbon monoxide gas. This toxic gas might then be distributed throughout the house by the furnace duct system.

In upow applications, the return air can be brought in

through the bottom or either side of the furnace. If a furnace with bottom return air is installed on a platform, make an airtight seal between the bottom of the furnace and the platform to ensure that the unit operates properly and safely. Use berglass sealing strips, caulking, or equivalent sealing method between the plenum and the furnace

cabinet to ensure a tight seal. If a lter is installed, size the return air duct to t the lter frame.

Venting

A 4-inch diameter ue transition is factory-installed on

the combustion air inducer outlet of all models. Figure 16 shows the combustion air inducer as shipped from the factory.

Mounting Screws Location

mounting screws

2 - Use tin snips to cut preferred opening on the

cabine for repositioning the ue outlet. Use the cut

out piece as a cover plate to patch unused opening on cabinet.

UPFlow Position

UPFLOW POSITION

Top Vent Discharge

vent pipe

flue

transition

pressure

switch

make-up

box

collector box

mounting screw

FIGURE 15

IMPORTANT

The unit will not vent properly with the ue transition

pointed down in the 6 o’clock position. The combustion air inducer may be rotated clockwise or counterclockwise by 90° to allow for top or side vent discharge in all

applications. When the unit is installed, the ue transition

must be in the 9 o’clock, 12 o’clock or 3 o’clock position.

If necessary reposition the combustion air inducer, pressure switch and or make up box as needed per the follow-

ing steps and see gures 16 through 22.

1 - Remove the four mounting screws (gure 15)

whic secure the combustion air inducer / pressure

switch assembly to the orice plate. Lift and rotate

the assembly 90 degrees clockwise or counter clockwise to either the 3 o’clock position or to 9 o’clock position and re-secure with four screws. Gasket should be left in place.

FLOW

AIR

FIGURE 16

UPFLOW POSITION

Left Side Vent Discharge

cover plate

pressure

switch

vent pipe

flue

transition

FLOW

AIR

Gas supply piping must be brought into the unit from the right

side in order to accommodate the flue pipe. Remove make-up box assembly (2 screws) and cut wire tie to

free make-up box wires. Re-install make-up box on other side of cabinet.

Re-secure make-up box wires, either pulling excess wires through the blower compartment and securing with supplied wire tie, or coil excess wire and secure to the gas manifold.

collector box

make-up

box

FIGURE 17

Page 13

pressure switch

Right Side Vent Discharge

collector box

UPFLOW POSITION

cover plate

flue transition

HORIZONTAL LEFT POSITION

Side Vent Discharge

pressure switch

vent pipe

AIR

make-up

box

FLOW

AIR

Pressure switch tubing may be too long. Cut to

fit , then re-attach to barbed fitting on pressure switch. Tubing must not be allowed to sag.

FIGURE 18

HORIZONTAL LEFT POSITION

Top Vent Discharge

vent pipe

flue

transition

cover plate

pressure switch

AIR

FLOW

flue transition

make-up box

Disconnect pressure switch hose from barbed fitting on the

pressure switch assembly. Remove pressure switch assembly (1 screw) and cut wire tie to free pressure switch wires. Reinstall pressure switch on the other side of orifice plate and reconnect pressure switch hose.

Re-secure pressure switch wires by either pulling excess wires through the blower compartment and securing with supplied wire tie, or coil excess wire and secure to the gas manifold.

collector box

FIGURE 20

HORIZONTAL RIGHT POSITION

Top Vent Discharge

vent pipe

flue transition

AIR

pressure switch

cover plate

make-up box

Disconnect

sure switch assembly. Remove pressure switch assembly (1 screw) and cut wire tie to free pressure switch wires. Re-install pressure switch on the other side of orifice plate and re-connect pressure switch hose.

Re-secure pressure switch wires by either pulling excess wires through the blower compartment and securing with supplied wire tie or coil excess wire and secure to the gas manifold.

collector box

FIGURE 19

Page 14

FLOW

collector box

make-up box

Gas supply piping must be brought into the unit from the bottom

in order to accommodate the flue pipe. Remove make-up box assembly (2 screws) and cut wire tie to

free make-up box wires. Re-install make-up box on other side of cabinet.

Re-secure make-up box wires by either pulling excess wires through the blower compartment and securing with supplied wire tie, or coil excess wire and secure to the gas manifold.

FIGURE 21

AIR

HORIZONTAL RIGHT POSITION

Side Vent Discharge

pressure switch

ENT CONNECTION

VENT PIPE

(min. 6” length)

“DISCONNECTED VENT”

WARNING

STICKER

FLOW

make up box

FIGURE 22

The SL280UHV series units are classied as fan-assisted

Category I furnaces when vertically vented according to the latest edition of National Fuel Gas Code (NFPA 54 / ANSI Z223.1) in the USA. A fan-assisted Category I furnace is an appliance equipped with an integral mechanical means to either draw or force combustion products through the combustion chamber and/or heat exchanger. The SL280UHV is not approved for use with horizontal venting.

NOTE - Use these instructions as a guide. They do not supersede local codes. This furnace must be vented according to all local codes these installation instructions, and the provided venting tables in these instructions

The venting tables in this manual were extracted from the National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are provided as a guide for proper vent installation. Proper application, termination, construction and location of vents must conform to local codes having jurisdiction. In the ab-

sence of local codes, the NFGC serves as the dening

document. Refer to the tables and the venting information contained

in these instructions to properly size and install the venting system.

flue transition

collector box

IMPORTANT

Once the venting system is installed, attach the “Disconnected Vent” warning sticker to a visible area

of the plenum near the vent pipe. See gure 23. The

warning sticker is provided in the bag assembly. Order kit 66W04 for additional stickers.

FLUE TRANSITION

COLLAR

FIGURE 23

Use self-drilling sheet metal screws or a mechanical fas-

tener to rmly secure the vent pipe to the round collar of the ue transition. If self-drilling screws are used to attach

the vent pipe, it is recommended that three be used. Drive one self-drilling screw through the front and one through

each side of the vent pipe and collar. See gures 20, 22 and 23. Install the rst vent connector elbow at a minimum

of six inches (152 mm) from the furnace vent outlet. See

gure 23.

Venting Using a Masonry Chimney

The following additional requirements apply when a lined masonry chimney is used to vent this furnace. Masonry chimneys used to vent Category I central furnaces must be either tile-lined or lined with a listed metal lining system or dedicated gas vent. Unlined masonry chimneys are

prohibited. See gures 24 and 25 for common venting.

A chimney with one or more sides exposed to the outside of the structure is considered to be an exterior chimney. An exterior masonry chimney that is not tile-lined must be

lined with B1 vent or a listed insulated exible metal vent.

An exterior tile-lined chimney that is sealed and capped

may be lined with a listed uninsulated exible metal vent.

If the existing chimney will not accommodate a listed metal liner, either the chimney must be rebuilt to accommodate one of these liners or an alternate approved venting method must be found.

Insulation for the exible vent pipe must be an encapsulated berglass sleeve recommended by the exible vent pipe manufacturer. See gure 24.

WARNING

Asphyxiation hazard. The exhaust vent for this furnace

must be securely connected to the furnace ue

transition at all times.

Page 15

Common Venting Using Metal-Lined Masonry Chimney

Common Venting Using Tile-Lined Interior Masonry Chimney and Combined Vent Connector

MINIMUM LENGTH = AS SHORT AS PRACTICAL. FOR MAXIMUM LENGTH SEE NOTE TO LEFT

INTERIOR TILE-LINED MASONRY CHIMNEY

NOTE - the chimney must be properly sized per provided venting tables or lined with listed metal lining system.

PERMANENTLY SEALED FIREPLACE OPENING

VENT

CONNECTOR

NOTE- Refer to provided venting tables for installations.

FURNACE

OTHER

APPLIANCE

AIR FLOW

SEALED

MAX. LENGTH

-- SEE NOTE 1

5 ft. (1.5 m)

minimum

VENT CONNECTOR

4 in. (102 mm)

minimum

OTHER

APPLIANCE

NOTE 1 - Refer to the provided venting tables for installations. Refer to the capacity requirements shown in the provided venting tables.

BELOW.

MIN. LENGTH -- AS

SHORT AS PRACTICAL

FURNACE

AIR FLOW

EXTERIOR

CHIMNEY WITH

METAL

LINER

PERMANENTLY

SEALED FIREPLACE

OPENING

FIGURE 24

DO NOT insulate the space between the liner and the chimney wall with puffed mica or any other loose granular insulating material

IMPORTANT

SINGLE appliance venting of a fan-assisted furnace into a tile-lined masonry chimney (interior or outside wall)

is PROHIBITED. The chimney must rst be lined with either type B1 vent or an insulated single wall exible

vent lining system which has been sized according to the provided venting tables and the vent pipe manufacturer’s instructions.

A fan-assisted furnace may be commonly vented into an existing lined masonry chimney if the following conditions are met:

• The chimney is currently serving at least one drafthood equipped appliance

• The vent connectors and chimney are sized according to the provided venting tables.

If type B1 double-wall vent is used inside a chimney, no other appliance can be vented into the chimney. The out-

er wall of type B1 vent pipe must not be exposed to ue

products.

FIGURE 25

Page 16

A type B1 vent or masonry chimney liner shall terminate above the roof surface with a listed cap or a listed roof assembly according to the terms of their respective listings and the vent manufacturer’s instructions.

When inspection reveals that an existing chimney is not safe for the intended purpose, it shall be rebuilt to conform to nationally recognized standards, lined or relined with suitable materials, or replaced with a gas vent or chimney suitable for venting SL280UHV series units. The chimney passageway must be checked periodically to ensure that it is clear and free of obstructions.

Do not install a manual damper, barometric draft regulator,

or ue restrictor between the furnace and the chimney.

Never connect a Category I appliance to a chimney that is

servicing a solid-fuel appliance. If a replace chimney ue is used to vent this appliance, the replace opening must

be permanently sealed. A type B or listed chimney lining system that passes

through an unused masonry chimney ue is not considered to be exposed to the outdoors.

General Venting Requirements

Vent all SL280UHV furnaces according to these instructions:

1 - Vent diameter recommendations and maximum

allowable piping runs are found in the provided venting tables

2 - In no case should the vent or vent connector

diameter be less than the diameter specied in the

provided venting tables.

3 - The minimum vent capacity determined by the

sizing tables must be less than the low re input

rating and the maximum vent capacity must be

greater than the high re input rating.

4 - Single appliance vents - If the vertical vent or tile-

lined chimney has a larger diameter or ow area than

the vent connector, use the vertical vent diameter to determine the minimum vent capacity and the vent connector diameter to determine the maximum vent

capacity. The ow area of the vertical vent, however, shall not exceed 7 times the ow area of the listed

appliance categorized vent area, drafthood outlet

area or ue collar area unless designed according

to approved engineering methods.

5 - Multiple appliance vents - The ow area of the

largest section of vertical vent or chimney shall not exceed 7 times the smallest listed appliance

categorized vent area, drafthood outlet area or ue

collar area unless designed according to approved engineering methods.

6 - The entire length of single wall metal vent connector

shall be readily accessible for inspection, cleaning, and replacement.

7 - Single appliance venting congurations with zero

lateral lengths (table 3) are assumed to have no elbows in the vent system. For all other vent

congurations, the vent system is assumed to have

two 90° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10% (0.90 x maximum listed capacity).

8 - The common venting tables (4 and 5) were

generated using a maximum horizontal vent connector length of 1-1/2 feet (.46 m) for each inch (25 mm) of connector diameter as follows:

TABLE 2

Connector Diameter

inches (mm)

3 (76) 4-1/2 (1.37)

4 (102) 6 (1.83)

5 (127) 7-1/2 (2.29)

6 (152) 10-1/2 (3.20)

7 (178) 10-1/2 (3.20)

Maximum Horizontal

Connector Length feet (m)

9 - If the common vertical vent is offset, the maximum

common vent capacity listed in the common venting tables should be reduced by 20%, the equivalent of two 90° elbows (0.80 x maximum common vent capacity). The horizontal length of the offset shall not exceed 1-1/2 feet (.46 m) for each inch (25 mm) of common vent diameter.

10 - The vent pipe should be as short as possible with

the least number of elbows and angles required to complete the job. Route the vent connector to the vent using the shortest possible route.

11 - A vent connector shall be supported without any

dips or sags and shall slope a minimum of 1/4 inch (6.4 mm) per linear foot (305 mm) of connector, back toward the appliance.

12 - Vent connectors shall be rmly attached to the

furnace ue collar by self-drilling screws or other

approved means, except vent connectors of listed type B vent material which shall be assembled according to the manufacturer’s instructions. Joints between sections of single wall connector piping shall be fastened by screws or other approved means.

13 - When the vent connector used for Category I

appliances must be located in or pass through a crawlspace, attic or other areas which may be cold, that portion of the vent connector shall be constructed of listed double-wall type B vent material or material having equivalent insulation qualities.

Page 17

14 - All venting pipe passing through oors, walls, and

ceilings must be installed with the listed clearance

to combustible materials and be re stopped

according to local codes. In absence of local codes, refer to NFGC (Z223.1).

15 - No portion of the venting system can extend into,

or pass through any circulation air duct or plenum.

16 - Vent connectors serving Category I appliances shall

not be connected to any portion of mechanical draft systems operating under positive pressure such as Category III or IV venting systems

17 - If vent connectors are combined prior to entering the

common vent, the maximum common vent capacity listed in the common venting tables must be reduced by 10%, the equivalent of one 90° elbow (0.90 x maximum common vent capacity).

18 - The common vent diameter must always be at least

as large as the largest vent connector diameter.

19 - In no case, shall the vent connector be sized more

than two consecutive table size diameters over the

size of the draft hood outlet or ue collar outlet.

20 - Do not install a manual damper, barometric draft

regulator or ue restrictor between the furnace and

the chimney.

21 - When connecting this appliance to an existing

dedicated or common venting system, you must inspect the venting system’s general condition and look for signs of corrosion. The existing vent pipe size must conform to these instructions and the provided venting tables. If the existing venting system does not meet these requirements, it must be resized.

TABLE 3

Capacity of Type B Double-Wall Vents with Type B Double-Wall Connectors

Serving a Single Category I Appliance

Vent and Connector Diameter - D (inches)

Height

(feet)

NOTE - Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows mum listed capacity).

Lateral

(feet)

0 0 78 0 152 0 251 0 375

2 13 51 18 97 27 157 32 232

4 21 49 30 94 39 153 50 227

6 25 46 36 91 47 149 59 223

0 0 84 0 165 0 276 0 415

2 12 57 16 109 25 178 28 263

5 23 53 32 103 42 171 53 255

8 28 49 39 98 51 164 64 247

0 0 88 0 175 0 295 0 447

2 12 61 17 11 8 23 194 26 289

5 23 57 32 11 3 41 187 52 280

10 30 51 41 104 54 176 67 267

0 0 94 0 191 0 327 0 502

2 11 69 15 136 20 226 22 339

5 22 65 30 130 39 219 49 330

10 29 59 40 121 51 206 64 315

15 35 53 48 11 2 61 195 76 301

0 0 97 0 202 0 349 0 540

2 10 75 14 149 18 250 20 377

5 21 71 29 143 38 242 47 367

10 28 64 38 133 50 229 62 351

15 34 58 46 124 59 217 73 337

20 48 52 55 11 6 69 206 84 322

0 0 100 0 213 0 374 0 587

2 9 81 13 166 14 283 18 432

5 21 77 28 160 36 275 45 421

10 27 70 37 150 48 262 59 405

15 33 64 44 141 57 249 70 389

20 56 58 53 132 66 237 80 374

30 NR NR 73 113 88 214 104 346

3 Inch 4 Inch 5 Inch 6 Inch

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

Page 18

TABLE 4

Vent and Connector Diameter - D (inches)

Common Vent Diameter - D (inches)

Vent Connector Capacity

Type B Double-Wall Vents with Type B Double-Wall Connectors

Serving Two or More Category I Appliances

Vent

Height

(feet)

Connector

Rise

(feet)

1 22 37 35 66 46 106 58 164

2 23 41 37 75 48 121 60 183

3 24 44 38 81 49 132 62 199

1 22 40 35 72 49 11 4 64 176

2 23 44 36 80 51 128 66 195

3 24 47 37 87 53 139 67 210

1 22 43 34 78 49 123 65 189

2 23 47 36 86 51 136 67 206

3 24 50 37 92 52 146 69 220

1 21 50 33 89 47 142 64 220

2 22 53 35 96 49 153 66 235

3 24 55 36 102 51 163 68 248

1 21 54 33 99 46 157 62 246

2 22 57 34 105 48 167 64 259

3 23 60 35 11 0 50 176 66 271

1 20 62 31 11 3 45 181 60 288

2 21 64 33 11 8 47 190 62 299

3 22 66 34 123 48 198 64 309

3 Inch 4 Inch 5 Inch 6 Inch

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

TABLE 5

Common Vent Capacity

Type B Double-Wall Vents with Type B Double-Wall Connectors

Serving Two or More Category I Appliances

Vent

Height

(feet)

6 92 81 140 11 6 204 161 309 248

8 101 90 155 129 224 178 339 275

10 110 97 169 141 243 194 367 299

15 125 112 195 164 283 228 427 352

20 136 123 215 183 314 255 475 394

30 152 138 244 210 361 297 547 459

FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT

4 Inch 5 Inch 6 Inch 7 Inch

Appliance Input Rating in Thousands of Btu Per Hour

Page 19

Removal of the Furnace from Common Vent

In the event that an existing furnace is removed from a venting system commonly run with separate gas appliances, the venting system is likely to be too large to properly vent the remaining attached appliances. Conduct the following test while each appliance is operating and the other appliances (which are not operating) remain connected to the common venting system. If the venting system has been installed improperly, you must correct the system as indicated in the general venting requirements section.

WARNING

CARBON MONOXIDE POISONING HAZARD Failure to follow the steps outlined below for each

appliance connected to the venting system being placed into operation could result in carbon monoxide poisoning or death. The following steps shall be followed for each appliance connected to the venting system being placed into operation, while all other appliances connected to the venting system are not in operation:

1 - Seal any unused openings in the common venting

system.

2 - Inspect the venting system for proper size and

horizontal pitch. Determine that there is no blockage,

restriction, leakage, corrosion, or other deciencies

which could cause an unsafe condition.

3 - Close all building doors and windows and all

doors between the space in which the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dryers and any appliances not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at maximum speed. Do not

operate a summer exhaust fan. Close replace

dampers.

4 - Follow the lighting instructions. Turn on the appliance

that is being inspected. Adjust the thermostat so that the appliance operates continuously.

5 - After the main burner has operated for 5 minutes,

test for leaks of ue gases at the draft hood relief opening. Use the ame of a match or candle, or

smoke from a cigarette, cigar, or pipe.

6 - After determining that each appliance connected

to the common venting system is venting properly, (step 3) return all doors, widows, exhaust fans,

replace dampers, and any other gas-burning

appliances to their previous mode of operation.

7 - If a venting problem is found during any of the

preceding tests, the common venting system must

be modied to correct the problem.

Resize the common venting system to the minimum vent pipe size determined by using the appropriate tables in Appendix G. (These are in the current standards of the National Fuel Gas Code ANSI Z223.1.

Page 20

Gas Piping

CAUTION

If a exible gas connector is required or allowed by

the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside

the furnace cabinet. The exible connector can then

be added between the black iron pipe and the gas supply line.

Gas Supply

WARNING

Do not over torque (800 in-lbs) or under torque (350 in-lbs) when attaching the gas piping to the gas valve.

1 - This unit is shipped standard for left or right side

installation of gas piping (or top entry in horizontal applications). Connect the gas supply piping into the gas valve. The maximum torque is 800 in lbs and minimum torque is 350 in lbs when when attaching the gas piping to the gas valve.

2 - When connecting the gas supply piping, consider

factors such as length of run, number of ttings, and

furnace rating to avoid excessive pressure drop. Table 6 lists recommended pipe sizes for typical applications.

3 - The gas piping must not run in or through air ducts,

clothes chutes, gas vents or chimneys, dumb waiters, or elevator shafts.

4 - The piping should be sloped 1/4 inch (6.4 mm) per

15 feet (4.57 m) upward toward the meter from the furnace. The piping must be supported at proper intervals [every 8 to 10 feet (2.44 to 3.01 m)] with suitable hangers or straps. Install a drip leg in vertical pipe runs to the unit.

5 - A 1/8” N.P.T. plugged tap or pressure post is located

on the gas valve to facilitate test gauge connection.

See gures 34 and 35.

6 - In some localities, codes may require the installation

of a manual main shut-off valve and union (furnished by the installer) external to the unit. The union must be of the ground joint type.

IMPORTANT

Compounds used on threaded joints of gas piping must

be resistant to the actions of liquied petroleum gases.

NOTE - If emergency shutoff is necessary, shut off the main manual gas valve and disconnect main power to the furnace. The installer should properly label these devices.

Gas Pipe Capacity - ft3/hr (m3/hr)

Nominal

Iron Pipe

Size

inches

(mm)

1/2

(12.7)

3/4

(19.05)

(25.4)

1-1/4

(31.75)

1-1/2

(38.1)

(50.8)

2-1/2

(63.5)

(76.2)

Internal

Diameter

inches

(mm)

.622

(17.799)

.824

(20.930)

1.049

(26.645)

1.380

(35.052)

1.610

(40.894)

2.067

(52.502)

2.469

(67.713)

3.068

(77.927)

TABLE 6

Gas Pipe Capacity - ft3/hr (m3/hr)

Length of Pipe - feet (m)

(3.048)20(6.096)30(9.144)40(12.192)50(15.240)60(18.288)70(21.336)80(24.384)90(27.432)

175

(4.96)

360

(10.19)

680

(919.25)

1400

(39.64)

2100

(59.46)

3950

(111.85)

6300

(178.39)

11000

(311.48)

120

(3.40)

250

(7.08)

465

(13.17)

950

(26.90)

460

(41.34)

2750

(77.87)

4350

(123.17)

7700

(218.03)

(2.75)

200

(5.66)

375

(10.62)

770

(21.80)

1180

(33.41)

2200

(62.30)

3520

(99.67)

6250

(176.98)

(2.32)

170

(4.81)

320

(9.06)

660

(18.69)

990

(28.03)

1900

(53.80)

3000

(84.95

5300

(150.07)

(2.07)

151

(4.28)

285

(8.07)

580

(16.42)

900

(25.48)

1680

(47.57)

2650

(75.04)

4750

(134.50)

(1.87)

138

(3.91)

260

(7.36)

530

(15.01)

810

(22.94)

1520

(43.04)

2400

(67.96)

4300

(121.76)

(1.73)

125

(3.54)

240

(6.80)

490

(13.87)

750

(21.24)

1400

(39.64)

2250

(63.71)

3900

(110.43)

(1.61)

118

(3.34)

220

(6.23)

460

(13.03)

690

(19.54)

1300

(36.81)

2050

(58.05)

3700

(104.77)

(1.50)

110

(3.11)

205

(5.80)

430

(12.18)

650

(18.41)

1220

(34.55)

1950

(55.22)

3450

(97.69)

100

(30.480)

(1.42)

103

(2.92)

195

(5.52)

400

(11.33)

620

(17.56)

1150

(32.56)

1850

(52.38)

3250

(92.03)

Page 21

MANUAL

Horizontal Applications

MAIN SHUT-OFF

VALV E

(With 1/8 in. NPT

Plugged Ta p Shown)

GROUND

JOINT

UNION

Left Side Piping

(Standard)

AUTOMATIC

GAS VALV E

AUTOMATIC

GAS VALV E

MANUAL

MAIN SHUT-OFF

VALV E

(With 1/8 in. NPT

Plugged Ta p

Shown)

GROUND

JOINT

UNION

DRIP LEG

NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET

AND INSTALLED

FIGURE 26

Possible Gas Piping Configurations

MANUAL

MAIN SHUT-OFF

VALV E

GROUND

JOINT

UNION

DRIP LEG

PROVIDED

INSTALLED

Horizontal Application

Right-Side Air Discharge

NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET

FIGURE 27

Leak Check

After gas piping is completed, carefully check all piping

connections (factory- and eld-installed) for gas leaks.

Use a leak detecting solution or other preferred means.

NOTE - If emergency shutoff is necessary, shut off the main manual gas valve and disconnect the main power to the furnace. The installer should properly label these devices.

CAUTION

Some soaps used for leak detection are corrosive to certain metals. Carefully rinse piping thoroughly after leak test has been completed. Do not use matches,

candles, ame or other sources of ignition to check for

gas leaks.

FIELD

PROVIDED

MANUAL

MAIN SHUT-OFF

VALV E

Right Side Piping

Horizontal Application

Left-Side Air Discharge

MANUAL

MAIN SHUT-OFF

VALV E

GROUND

JOINT

UNION

DRIP LEG

FIELD

AND

GROUND

JOINT

UNION

DRIP LEG

IMPORTANT

When testing pressure of gas lines, gas valve must

be disconnected and isolated. See gure 28. Gas

valves can be damaged if subjected to pressures greater than 1/2 psig (3.48 kPa, 14 inches w.c.)..

MANUAL MAIN

SHUT-OFF VALV E

WILL NOT HOLD

NORMAL TEST

PRESSURE

1/8 NPT PLUG

CAP

ISOLATE

GAS VALV E

(Alternate)

FURNACE

The furnace must be isolated by closing its individual manual shut-off valve and disconnecting from from the gas supply system the during any pressure testing of the gas supply system at pressures less than or equal to 1/2 psig (3.48 kPa, 14 inches w.c.)

FIGURE 28

Page 22

Electrical

WARNING

Electrostatic discharge can affect electronic components. Take care during unit installation and service to

ELECTROSTATIC

DISCHARGE

(ESD)

Precautions and

Procedures

The unit is equipped with a eld make-up box on the left

hand side of the cabinet. The make-up box may be moved to the right side of the furnace to facilitate installation. If the make-up box is moved to the right side, clip the wire ties that bundle the wires together. The excess wire must be pulled into the blower compartment. Secure the excess wire to the existing harness to protect it from damage.

INTERIOR MAKE-UP BOX INSTALLATION

Right Side

BOX

protect the unit’s electronic controls. Precautions will help to avoid control exposure to electrostatic discharge by putting the unit, the control and the technician at the same electrostatic potential. Touch hand and all tools on an unpainted unit surface before performing any service procedure to neutralize electrostatic charge.

CAUTION

Failure to use properly sized wiring and circuit breaker may result in property damage. Size wiring and circuit

breaker(s) per Product Specications bulletin (EHB) and

unit rating plate.

NOTE - Unit nameplate states maximum current draw. Maximum over-current protection allowed is shown in ta-

ble 7.

TABLE 7TABLE 7

SL280UH Maximum Over-Current

Protection (Amps)

070V36A, 09036B 15

090V48B, 090V60C,

110V60C, 135V60D

2 - Holes are on both sides of the furnace cabinet to

facilitate wiring.

3 - Install a separate (properly sized) disconnect switch

near the furnace so that power can be turned off for servicing.

4 - Before connecting the thermostat or the power

wiring, check to make sure the wires will be long enough for servicing at a later date. Remove the blower access panel to check the length of the wire.

5 - Complete the wiring connections to the equipment.

Use the provided unit wiring diagram and the eld wiring diagrams shown in table 8 and gure 32. Use

18-gauge wire or larger that is suitable for Class II rating for thermostat connections.

6 - Electrically ground the unit according to local codes

or, in the absence of local codes, according to the current National Electric Code (ANSI/NFPA No. 70).

A green ground wire is provided in the eld make-up

box.

NOTE - The SL280UHV furnace contains electronic components that are polarity sensitive. Make sure that the furnace is wired correctly and is properly grounded.

FIGURE 29

WARNING

Fire Hazard. Use of aluminum wire with this product may

result in a re, causing property damage, severe injury

or death. Use copper wire only with this product.

See gures 30 and 31 for icomfort Touch® thermostat

wiring in communicating applications. Table 8 shows DIP switch and on-board link settings for non-communicating thermostat applications. Typical wiring schematic is

shown in gure 32.

1 - The power supply wiring must meet Class I

restrictions. Protected by either a fuse or circuit breaker, select circuit protection and wire size according to unit nameplate.

WARNING

Electric Shock Hazard. Can cause injury or death. Unit must be properly grounded in accordance with national

and local codes.

7 - One line voltage “ACC” 1/4” spade terminal is

provided on the furnace integrated control. Any electronic air cleaner or other accessory rated up to one amp can be connected to this terminal with the neutral leg of the circuit being connected to the

one of the provided neutral terminals. See gure 33 for control conguration. This terminal is energized

when the indoor blower is operating.

Page 23

8 - An unpowered, normally open (dry) set of contacts

with a 1/4” spade terminal “HUM” are provided for

humidier connections and may be connected to 24V or 120V. Any humidier rated up to one amp can be connected to these terminals. In 120V humidier

applications the neutral leg of the circuit can be connected to one of the provided neutral terminals. This terminal is energized in the heating mode.

9 - Install the room thermostat according to the

instructions provided with the thermostat. See table 8

for eld wiring connections in varying applications. If

the furnace is being matched with a heat pump, refer to the instruction packaged with the dual fuel thermostat.

Thermostat Selection

CAUTION

Field wiring for both communicating and noncommunicating applications is illustrated in diagrams, which begin on Page 25..

Non-Communicating

In non-communicating applications the SL280UHV is designed to operate in a SINGLE-STAGE mode or TWOSTAGE mode using a conventional thermostat.

For optimal performance in non-communicating applications, Lennox recommends use of a ComfortSense® 7000

high quality electronic digital thermostat or any other with adjustable settings for 1st stage / 2nd stage on / off differ-

entials and adjustable stage timers. Lennox recommends the following two-stage thermostat settings: First heat stage differential set to 1/2 to 1 degree F; sec-

ond heat stage differential set to 1/2 or 1 degree F; second heat stage upstage timer disabled, or set to maximum (1 hr minimum).

Communicating

In communicating applications the icomfort Wi-Fi® thermostat must be used. Refer to the instructions provided with the thermostat for installation, set-up and operation. In communicating system all unused thermostat wire in the wire bundle needs to be terminated inside and out. The extra wires can terminate on the ‘C” terminal of the icomfort communication terminal strip. (RSBus). Using an additiona wire come off ”C” terminal and wire nut all the extra wires together. Termination on the outdoor control must match the indoor control.

Indoor Blower Speeds

Non-Communicating

1 - When the thermostat is set to “FAN ON,” the indoor

blower will run continuously at a eld selectable

percentage of the second-stage cooling speed when there is no cooling or heating demand. The factory defaul setting is 38% of cool speed.

2 - When the SL280UHV is running in the heating

mode, the indoor blower will run on the heating speed designated by the positions of DIP switches 11, 12 and 13. First stage heating will run at 91% heat speed.

3 - When there is a cooling demand, the indoor blower

will run on the cooling speed designated by the positions of DIP switches 5 and 6. First stage cooling will run at 70% cool speed.

Communicating

NOTE - When the SL280UHV is used with icomfort Wi-

Fi® thermostat, proper indoor blower speed selections are made by the communicating thermostat.

1 - When the thermostat is set to “FAN ON,” the indoor

blower will run at setting determined during system

conguration.

2 - When there is a heating demand the fan will run on

heating speeds for ring rate.

3 - When there is a cooling demand, the fan will run on

the rst stage and second stage cooling speed set

using the icomfort Wi-Fi® thermostat in the installer setup mode. The factory default is based upon 400 CFM a ton.

Generator Use - Voltage Requirements

The following requirements must be kept in mind when specifying a generator for use with this equipment:

• The furnace requires 120 volts (Range: 102 volts to 132 volts)

• The furnace operates at 60 Hz + 5% (Range: 57 Hz to 63 Hz)

• The furnace integrated control requires both correct polarity and proper ground. Both polarity and proper grounding should be checked before attempting to operate the furnace on either permanent or temporary power

• Generator should have a wave form distortion of less than 5% THD (total harmonic distortion)

Page 24

iComfort® Thermostat with a

Non-Communicating Outdoor Unit

iComfort

ENABLED

FURNACE

iComfort

ENABLED

THERMOSTAT

NON-COMMUNICATING

OUTDOOR AIR

CONDITIONING UNIT -

1 OR 2 STAGE

iComforti® Thermostat iComfort

-Enabled Indoor Furnace

Non-Communicating Outdoor Air Conditioner

OPTIONAL OUTDOOR

AIR SENSOR

OPTIONAL

DISCHARGE

AIR SENSOR

iComforti® Thermostat with an iComfort

ENABLED Outdoor Unit

icomfort® Thermostat iComfort

Enabled Indoor Furnace

iComfort

Enabled Outdoor Air Conditioner or Heat Pump

iComfort

ENABLED FURNACE

iComfort

- ENABLED

OUTDOOR AIR CONDITIONING

OR HEAT PUMP UNIT

OPTIONAL OUTDOOR

AIR SENSOR

OPTIONAL

DISCHARGE

AIR SENSOR

CLIP ON-BOARD LINK W915 (Y1 TO Y2) FOR

TWO-STAGE OPERATION

iComfort

THERMOSTAT

Communicating systems using the iComfort®thermostat require four thermostat wires between the thermostat and the furnace/air handler control and four wires between the outdoor unit and the furnace/air handler control. When a thermostat cable with more than four wires is used, the extra wires must be properly connected to avoid electrical noise. The wires must not be left disconnected.

Use wire nuts to bundle the four unused wires at each end of the cable. A single wire should then be connected to the indoor unit end of the wire bundle and attached to the “C” terminals as shown below.

Indoor Unit Controller

Outdoor Unit

iComfort

thermostat

Single wire to terminal C

Unused wires

FIGURE 30

Page 25

Optional Accessories for use with any iComfort Touch

System

NOTE: iComfort® THERMOSTAT SENSES HUMIDITY & CONTROLS HUM CONTACTS TO CYCLE HUMIDIFIER BASED ON DEMAND. NO OTHER CONTROL OR HUMIDISTAT REQUIRED.

OPTIONAL OUTDOOR AIR SENSOR FOR USE WITH HUMIDIFIER (IF NOT ALREADY IN THE SYSTEM FOR OTHER FUNCTIONS. BUILT INTO ALL icomfort® by Lennox® OUTDOOR UNITS).

iComfort®ENABLED

Discharge Air

Sensor (Required

for even heat)

iComfort

THERMOSTAT

FURNACE

RSBus

Maximum total

nections on the RSBus is limited to 1500ft.

Wire gauge of RSBus wire is 18.

icomfort

DOOR AIR CONDITIONING

OR HEAT PUMP UNIT

NOTE: 24V UV LIGHT APPLICATIONS

In an iComfort® by Lennox® system, neither furnace nor air handler former will have adequate VA to power 24V UV light applications. An additional transformer for UV light applications is required.

iComfort

THERMOSTAT

DEHUMIDIFIER CONTROL

Rf WGhGsCf

HVAC EQUIP

120V CONNECTIONS

“HUM” CONTACT IS CLOSED ANYTIME HUMIDITY DEMAND IS PRESENT

24V HUMIDIFIER CONNECTIONS

THERMOSTAT

CONVENTIONAL

CATING SYSTEM

COMMUNICATING SYSTEM

*24V IN jumper not used in noncommunicating configuration

*24V IN JUMPER

iComfort® ENABLED FURNACE

icomfort ENABLED

FURNACE

HEPA BYPASS FILTER X2680 HEPA INTERLOCK KIT

FURNACE

icomfort ENABLED

LVCS VENTILATION CONTROL SYSTEM

FURNACE

icomfort ENABLED

(POWER COMPANY INTERRUPTION SYSTEMS ARE WIRED SAME AS OVERFLOW SWITCH)

PASS INDOOR BLOWER MOTOR COMMON WIRE THROUGH CURRENT LOOP.

SEE HEPA INTERLOCK KIT

TAILS

SEE LVCS VENTILATION INSTRUCTIONS FOR DAMPER & SENSOR WIRING

FIGURE 31

Page 26

HVAC EQUIPMENT

STANDARD 1 OR 2

STAGE AC OR HP UNIT

2 STAGE FURNACE

CUT R-DS W914

NON-COMMUNICATING SYSTEM WIRING

COMMUNICATING SYSTEM WIRING

Thermostat

* Not required on all units.

1 Heat / 1 Cool

NOTE - Use DIP switch 2 to set second-stage heat ON delay. OFF-7 minutes. ON-12 minutes.

TABLE 8

SL280 Field Wiring Applications With Conventional Thermostat

DIP Switch Settings and On-Board Links

DIP Switch 1

Thermostat

Heating

On Board Links Must Be Cut To Select

System Options

Stages

DO NOT CUT ANY ON-BOARD LINKS

Wiring Connections

T'STAT

FURNACE

TERM. STRIP

OUTDOOR

UNIT

1 Heat / 2 Cool

NOTE - Use DIP switch 2 to set second-stage heat ON delay. OFF-7 minutes. ON-12 minutes.

1 Heat / 2 Cool with t'stat with humidity control

NOTE - Use DIP switch 2 to set second-stage heat ON delay. OFF-7 minutes. ON-12 minutes.

CUT ON-BOARD LINK

W915

2 STAGE

COMPR

CUT ON-BOARD LINK

W915

2 STAGE

COMPR

CUT ON-BOARD LINK

W914

DEHUM

HARMONY

T'STAT

FURNACE

TERM. STRIP

FURNACE

TERM. STRIP

OUTDOOR

UNIT

OUTDOOR

UNIT

Page 27

Thermostat

DIP Switch Settings and On-Board Links

Wiring Connections

DIP Switch 1

Thermostat

Heating

Stages

On Board Links Must Be Cut To Select

System Options

2 Heat / 2 Cool OFF

CUT ON-BOARD LINK

W915

2 STAGE

COMPR

T'STAT

FURNACE

TERM. STRIP

OUTDOOR

UNIT

2 Heat / 2 Cool with t'stat with humidity control

OFF

CUT ON-BOARD LINK

W915

2 STAGE

COMPR

CUT ON-BOARD LINK

W914

DEHUM

HARMONY

T'STAT

FURNACE

TERM. STRIP

OUTDOOR

UNIT

2 Heat / 1 Cool with t'stat with humidity control

OFF

CUT ON-BOARD LINK

W914

DEHUM

HARMONY

T'STAT

FURNACE

TERM. STRIP

OUTDOOR

UNIT

2 Heat / 1 Cool OFF

DO NOT CUT ANY ON-BOARD LINKS

T'STAT

FURNACE

TERM. STRIP

OUTDOOR

UNIT

* Not required on all units.

Table 8

SL280 Field Wiring Applications With Conventional Thermostat (Continued)

Page 28

Thermostat

Dual Fuel Single Stage Heat Pump

ComfortSense thermostat w/

TABLE 8

SL280 Field Wiring Applications With Conventional Thermostat (Continued)

DIP Switch Settings and On-Board Links

DIP Switch 1

Thermostat

Heating

On Board Links Must Be Cut To Select

System Options

Wiring Connections

Stages

OFF

CUT ON-BOARD LINK

W951 HEAT

PUMP

T'STAT

FURNACE

TERM. STRIP

HEAT PUMP

67M41*

bilities Capable of 2 stage gas heat control

Dual Fuel Two Stage Heat Pump

ComfortSense thermostat w/

bilities Capable of 2 stage gas heat control

OFF

CUT ON-BOARD LINK

W915

2 STAGE

COMPR

CUT ON-BOARD LINK

W951 HEAT

PUMP

T'STAT

FURNACE

TERM. STRIP

67M41*

outdoor

sensor

HEAT PUMP

out blue

* Connect W1 to W1 ONLY if using defrost tempering kit 67M41

NOTE - Do NOT make a wire connection between the room thermostat L terminal and the L terminal of the furnace integrated control.

Page 29

outdoor sensor

Thermostat

integrated control.

Dual Fuel Single Stage Heat Pump

ComfortSense thermostat w/

TABLE 8

SL280 Field Wiring Applications With Conventional Thermostat (Continued)

DIP Switch Settings and On-Board Links

DIP Switch 1

Thermostat

Heating

On Board Links Must Be Cut To Select

System Options

Wiring Connections

Stages

OFF

T'STAT

CUT ON-BOARD LINK

W951 HEAT PUMP

FURNACE

TERM. STRIP

HEAT PUMP

67M41*

bilities Capable of 2 stage gas heat

midification control

Dual Fuel Two Stage Heat Pump

ComfortSense thermostat w/

bilities Capable of 2 stage gas heat

midification

OFF

CUT ON-BOARD LINK

W914

DEHUM

HARMONY

CUT ON-BOARD LINK

W915

2 STAGE

COMPR

CUT ON-BOARD LINK

W951 HEAT

PUMP

CUT ON-BOARD LINK

W914

DEHUM

HARMONY

T'STAT

FURNACE

TERM. STRIP

67M41*

outdoor

sensor

HEAT PUMP

out blue

* Connect W1 to W1 ONLY if using defrost tempering kit 67M41

NOTE - Do NOT make a wire connection between the room thermostat L terminal and the L terminal of the furnace

Page 30

outdoor

sensor

SL280UHV Schematic Wiring Diagram

FIGURE 32

Page 31

Integrated Control

HUM

LINE 1

7 SEGMENT LED

FLAME SENSE

DIAGNOSTIC

PUSH BUTTON

DIP SWITCHES

ACC

HS/ CAI

INDOOR

BLOWER

CONNECTOR

NEUTRAL

OUTDOOR AIR

SENSOR

TERMINALS

DISCHARGE AIR

SENSOR

TERMINALS

TB83

COMMUNICATING

OUTDOOR

EQUIPMENT

I +I -CRI +I -

TB84

COMMUNICATING

INDOOR

THERMOSTAT

RS-BUS LINK (TB82, future use)

I+ = DATA HIGH CONNECTION I - = DATA LOW CONNECTION

RS-BUS OUTDOOR (TB83)

R = 24VAC I + = DATA HIGH CONNECTION I - = DATA LOW CONNECTION C = 24VAXC COMMON

RS-BUS INDOOR (TB84)

R = 24VAC I + = DATA HIGH CONNECTION I - = DATA LOW CONNECTION C = 24VAXC COMMON

1/4” QUICK CONNECT TERMINALS

HUM = UNPOWERED NORMALLY OPEN (DRY) CONTACTS

XMFR = 120 VAC OUTPUT TO TRANSFORMER

LI = 120 VAC INPUT TO CONTROL

ACC = 120 VAC OUTPUT TO OPTIONAL ACCESSORY

NEUTRALS = 120 VAC NEUTRAL

W1 W2 GY2Y1

NON-COMMUNICATINGNG

24V TERMINALS

12 PIN LOW

VOLTAGE

CONNECTOR

W915 Y1 TO Y2

2 STAGE COMPR

W951 R TO O HEAT PUMP

W914 R TO DS

DEHUM OR

RDHL ODS

HARMONY

THERMOSTAT CONNECTIONS (TB1)

DS = DEHUMIDIFICATION SIGNAL W2 = HEAT DEMAND FROM 2ND STAGE T/STAT W1 = HEAT DEMAND FROM 1ST STAGE T/STAT

R = CLASS 2 VOLTAGE TO THERMOSTAT

G = MANUAL FAN FROM T'STAT

C = THERMOSTAT SIGNAL GROUND CONNECTED TO TRANSFORMER GRD (TR) & CHASIS GROUND (GRD)

Y1 = THERMOSTAT 1ST STAGE COOL SIGNAL

Y2 = THERMOSTAT 2ND STAGE COOL SIGNAL

O = THERMOSTAT SIGNAL TO HEAT PUMP

DH = DEHUMIDIFICATION OUTPUT COMMUNICATING

L = USE ONLY WITH A COMMUNICATING THERMOSTAT

AND A NON-COMMUNICATING OUTDOOR UNIT

REVERSING VALV E

THERMOSTAT ONLY

FIGURE 33

Page 32

Integrated Control DIP Switch Settings Conventional Thermostat (non-communicating)

SL280UHV units are equipped with a two-stage, variable speed integrated control. This control manages ignition timing, heating mode fan off delays and indoor blower speeds based on selections made using the control dip switches and jumpers. The control includes an internal watchguard feature which automatically resets the ignition control when it has been locked out. After one hour of continuous thermostat demand for heat, the watchguard will break and remake thermostat demand to the furnace and automatically reset the control to relight the furnace.

Note: All icomfort settings are set at the icomfort Touch® thermostat. See icomfort installation instruction. In icomfort communication system all DIP switch and clippable link settings are ignored. For conventional thermostats proceed with DIP switch and clippable link settings as outlined in the following.

Heating Operation DIP Switch Settings Switch 1 -- Thermostat Selection -- This unit may be

used with either a single-stage or two-stage thermostat. The thermostat selection is made using a DIP switch which must be properly positioned for the particular application. The DIP switch is factory-positioned for use with a twostage thermostat. If a single-stage thermostat is to be used, the DIP switch must be repositioned.

• Select “OFF” for two-stage heating operation controlled by a two-stage heating thermostat (factory setting);

• Select “ON” for two-stage heating operation controlled

by a single-stage heating thermostat. This setting provides a timed delay before second-stage heat is initiated.

Switch 2 -- Second Stage Delay (Used with SingleStage Thermostat Only) -- This switch is used to deter-

mine the second stage on delay when a single-stage thermostat is being used. The switch is factory-set in the OFF position, which provides a 7-minute delay before secondstage heat is initiated. If the switch is toggled to the ON position, it will provide a 12-minute delay before secondstage heat is initiated. This switch is only activated when the thermostat selector jumper is positioned for SINGLEstage thermostat use.

Switches 3 and 4 -- Blower-Off Delay -- The blower-on delay of 30 seconds is not adjustable. The blower-off delay (time that the blower operates after the heating de-

mand has been satised) can be adjusted by moving

switches 3 and 4 on the integrated control. The unit is shipped from the factory with a blower-off delay of 90 seconds. The blower off delay affects comfort and is adjustable to satisfy individual applications. Adjust the blower off delay to achieve a supply air temperature between 90° and 110°F at the exact moment that the blower is de-energized. Longer off delay settings provide lower supply air temperatures; shorter settings provide higher supply air

temperatures Table 9 provides the blower off timings that will result from different switch settings.

TABLE 9

Blower Off Delay Switch Settings

Blower Off Delay

Seconds

60 On Off

90 (factory) Off Off

120 Off On

180 On On

Switch 3 Switch 4

Indoor Blower Operation DIP Switch Settings Switches 5 and 6 -- Cooling Mode Blower Speed -- The

unit is shipped from the factory with the dip switches positioned for high speed (4) indoor blower motor operation during the cooling mode. Table 10 provides the cooling mode blower speeds that will result from different switch settings. Switches 5 and 6 set the blower cfm for secondstage cool. The integrated control automatically ramps

down to 70% of the second-stage cfm for rst-stage cfm.

Refer to tables for corresponding cfm values.

TABLE 10

Speed Switch 5 Switch 6

Low On On

Medium Low Off On

Medium High On Off

High (factory) Off Off

Switches 7 and 8 -- Cooling Blower Speed Adjustment

-- The unit is shipped from the factory with the dip switches positioned for NORMAL (no) adjustment. The dip switches may be positioned to adjust the blower speed by +10% or -10% to better suit the application. Table 11 below provides blower speed adjustments that will result from different switch settings. Refer to tables for corresponding cfm values.

TABLE 11

Adjustment Switch 7 Switch 8

+10% (approx) On Off

Factory Default Off Off

-10% (approx) Off On

Switches 9 and 10 -- Cooling Mode Blower Speed Ramping -- Blower speed ramping may be used to en-

hance dehumidication performance. The switches are

factory set at option A which has the greatest effect on de-

humidication performance. Table 12 provides the cooling

mode blower speed ramping options that will result from different switch settings. The cooling mode blower speed ramping options are detailed on the next page.

NOTE - The off portion of the selected ramp prole also applies during heat pump operation in dual fuel applications.

Page 33

TABLE 12

OFF

DEMAND

Cooling Mode Blower Speed Ramping

Ramping Switch 9 Switch 10

A (Factory) Off Off

B Off On

C On Off

D On On

Ramping Option A (Factory Selection)

• Motor runs at 50% for 30 seconds.

• Motor then runs at 82% for approximately 7-1/2 min-

utes.

• If demand has not been satised after 7-1/2 minutes,

motor runs at 100% until demand is satised.

• Once demand is met, motor runs at 50% for 30 sec-

onds then ramps down to stop.

OFF

1/2 MIN 50% CFM

7 1/2 MIN 82% CFM

COMPRESSOR DEMAND

100% CFM

1/2 MIN 50% CFM

Ramping Option B

• Motor runs at 82% for approximately 7-1/2 minutes. If

demand has not been satised after 7-1/2 minutes,motor runs at 100% until demand is satised.

• Once demand is met, motor ramps down to stop.

OFF

7 1/2 MIN

82%CFM

COMPRESSOR DEMAND

100% CFM

Ramping Option C

OFF

100% CFM

COMPRESSOR

100% CFM

45 SEC.

• Motor runs at 100% until demand is satised.

• Once demand is met, motor runs at 100% for 45 seconds then ramps down to stop.

Ramping Option D

• Motor runs at 100% until demand is satised.

• Once demand is met, motor ramps down to stop.

100% CFM

COMPRESSOR

DEMAND

OFFOFF

Switches 11, 12 and 13 -- Heating Mode Blower Speed

The switches are factory set to the OFF position which provides factory default heat speed. Refer to table 13 for switches 11, 12 and 13 that provided the corresponding increases or decrease to both high and low heat demand.

TABLE 13

Heating Mode Blower Speeds

Heat Speed Switch 11 Switch 12 Switch 13

Increase 24% On On On

Increase 18% On On Off

Increase 12% On Off On

Increae 6% On Off Off

Factory

Off Off Off

Default

Decrease 6% Off Off On

Decrease

Off On Off

12%

Decrease

Off On On

18%

Switches 14 and 15 -- Continuous Blower Speed

Table 14 provides continuous blower speed adjustments that will result from different switch settings.

TABLE 14

Continuous Blower Speed

Coninuous Blower Speed Switch 14 Switch 15

28% of High Cool Speed Off On

38% of High Cool Speed

(Factory)

Off Off

70% of High Cool Speed On Off

100% of High Cool Speed On On

NOTE - This instruction provides indoor blower CFM tables for bottom return air only. Refer to the Product Specications document for a complete list of CFM tables for all applications.

Page 34

On-Board Links

Note: In icomfort systems with a conventional outdoor unit (non-communicating), the on-board clippable links must be set to properly congure the system.

WARNING

Carefully review all conguration information provided.

Failure to properly set DIP switches, jumpers and onboard links can result in improper operation!

On-Board Link W914 Dehum or Harmony (R to DS)

On-board link W914, is a clippable connection between terminals R and DS on the integrated control. W914 must be cut when the furnace is installed with either the Harmony III zone control or a thermostat which features humidity control. If the link is left intact the PMW signal from the Harmony III control will be blocked and also lead to control damage. Refer to table 15 for operation sequence in applications including SL280UHV, a thermostat which features humidity control and a single-speed outdoor unit. Table 16 gives the operation sequence in applications with a twospeed outdoor unit.

On-Board Link W951 Heat Pump (R to O)

On-board link W951 is a clippable connection between terminals R and O on the integrated control. W951 must be cut when the furnace is installed in applications which include a heat pump unit and a thermostat which features dual fuel use. If the link is left intact, terminal “O” will remain energized eliminating the HEAT MODE in the heat pump.

On-Board Link W915 2 Stage Compr (Y1 to Y2)

On-board link W915 is a clippable connection between terminals Y1 and Y2 on the integrated control. W915 must be cut if two-stage cooling will be used. If the Y1 to Y2 link is not cut the outdoor unit will operate in second-stage cooling only.

Diagnostic LED (Figure 33)

The seven-segment diagnostic LED displays operating status, target airow, error codes and other information. The table beginning on Page 50 lists diagnostic LED codes.

Diagnostic Push Button (Figure 33)

The diagnostic push button is located adjacent to the seven-segment diagnostic LED. This button is used to enable the Error Code Recall “E” mode and the Flame Signal “F” mode. Press the button and hold it to cycle through a menu of options. Every ve seconds a new menu item will be displayed. When the button is released, the displayed item will be selected. Once all items in the menu have been displayed, the menu resumes from the beginning until the button is released.

Error Code Recall Mode Select ”E” from the menu to access the most recent 10

error codes. Select “c” from the Error Code Recall menu to clear all error codes. Button must be pressed a second time while “c” is ashing to conrm command to delete codes. Press the button until a solid “≡” is displayed to exit the Error Code Recall mode.

Flame Signal Mode

Select ”F” from the menu to access the ame signal mode. The integrated control will display the ame current on 7 segment LED in micro amps (uA).

Flame signal mode is exited after the following:

• Power is reset

• Pressing and holding push button until 3 horizontal

lines “≡” are displayed

• 10 minutes of entering the ame sense mode.

Page 35

BLOWER DATA

SL280UH070V36A BLOWER PERFORMANCE (less lter)

BOTTOM RETURN AIR

0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range

HEATING

Heating Speed

DIP Switch

Settings

+24% 1045 1145

+18% 985 1080

+12% 940 1035

+6% 880 960

Factory Default 850 925

–6% 785 875

–12% 745 815

–18% 680 745

Cooling Speed

DIP Switch

Settings

Low Medium-Low Medium-High2 High Low Medium-Low Medium-High2 High

+ 781 819 872 981 1045 1139 1219 1372

Factory Default 695 734 797 883 943 1005 1114 1260

– 645 674 720 815 847 922 991 1144

First Stage Heating Speed - cfm Second Stage Heating Speed - cfm

COOLING

First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm

BLOWER DATA

SL280UH090V36B BLOWER PERFORMANCE (less lter)

BOTTOM RETURN AIR

0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range

HEATING

Heating Speed

DIP Switch

Settings

+24% 1300 1420

+18% 1250 1335

+12% 1185 1285

+6% 1145 1240

Factory Default 1070 1170

–6% 1015 1100

–12% 970 1035

–18% 880 980

Cooling Speed

DIP Switch

Settings

Low Medium-Low Medium-High2 High Low Medium-Low Medium-High2 High

+ 616 755 846 980 1018 1197 1291 1399

Factory Default 571 698 767 886 909 1083 1197 1284

– 489 627 681 812 834 968 1081 1179

Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.

Factory default setting.

NOTES - The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage HEAT. First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 250 cfm. Lennox iHarmony® Zoning System Applications - Minimum blower speed is 250 cfm.

First Stage Heating Speed - cfm Second Stage Heating Speed - cfm

COOLING

First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm

Page 36

BLOWER DATA

SL280UH090V48B BLOWER PERFORMANCE (less lter)

BOTTOM RETURN AIR

0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range

HEATING

Heating Speed

DIP Switch

Settings

+24% 1280 1410

+18% 1220 1340

+12% 1155 1270

+6% 1095 1205

Factory Default 1035 1135

–6% 970 1070

–12% 910 1000

–18% 845 930

Cooling Speed

DIP Switch

Settings

Low Medium-Low Medium-High2 High Low Medium-Low Medium-High2 High

+ 670 890 1040 1210 1030 1335 1550 1755

Factory Default 605 815 965 1090 940 1205 1405 1,600

– 525 690 850 985 795 1060 1260 1435

First Stage Heating Speed - cfm Second Stage Heating Speed - cfm

COOLING

First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm

BLOWER DATA

SL280UH090V60C BLOWER PERFORMANCE (less lter)

BOTTOM RETURN AIR, RETURN AIR FROM BOTH SIDES OR RETURN AIR FROM BOTTOM AND ONE SIDE

0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range

HEATING

Heating Speed

DIP Switch

Settings

+24% 1420 1565

+18% 1355 1490

+12% 1285 1415

+6% 1215 1335

Factory Default 1145 1260

–6% 1080 1185

–12% 1010 111 0

–18% 940 1035

Cooling Speed

DIP Switch

Settings

Low Medium-Low Medium-High2 High Low Medium-Low Medium-High2 High

+ 1110 1205 1420 1680 1575 1740 2000 2305

Factory Default 1005 1100 1280 1545 1440 1595 1820 2125

– 890 1015 1125 1380 1295 1450 1610 1930

Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.

Factory default setting.

NOTES - The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage HEAT. First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 450 cfm. Lennox iHarmony® Zoning System Applications - Minimum blower speed is 450 cfm.

First Stage Heating Speed - cfm Second Stage Heating Speed - cfm

COOLING

First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm

Page 37

BLOWER DATA

SL280UH110V60C BLOWER PERFORMANCE (less lter)

BOTTOM RETURN AIR, RETURN AIR FROM BOTH SIDES OR RETURN AIR FROM BOTTOM AND ONE SIDE

0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range

HEATING

Heating Speed

DIP Switch

Settings

+24% 1690 1855

+18% 1605 1765

+12% 1525 1675

+6% 1445 1585

Factory Default 1360 1495

–6% 1280 1405

–12% 1200 1315

–18% 1115 1230

Cooling Speed

DIP Switch

Settings

Low Medium-Low Medium-High2 High Low Medium-Low Medium-High2 High

+ 1060 1220 1330 1565 1535 1710 1910 2210

Factory Default 970 1075 1180 1430 1400 1565 1715 2015

– 875 980 1070 1255 1260 1400 1560 1815

First Stage Heating Speed - cfm Second Stage Heating Speed - cfm

COOLING

First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm

BLOWER DATA

SL280UH135V60D BLOWER PERFORMANCE (less lter)

BOTTOM RETURN AIR, RETURN AIR FROM BOTH SIDES OR RETURN AIR FROM BOTTOM AND ONE SIDE

0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range

HEATING

Heating Speed

DIP Switch

Settings

+24% 1875 2065

+18% 1785 1965

+12% 1695 1865

+6% 1605 1765

Factory Default 1515 1665

–6% 1425 1565

–12% 1330 1465

–18% 1240 1365

Cooling Speed

DIP Switch

Settings

Low Medium-Low Medium-High2 High Low Medium-Low Medium-High2 High

+ 1025 1120 1325 1650 1500 1600 1840 2235

Factory Default 965 1015 1180 1490 1420 1510 1700 2110

– 875 930 1060 1350 1225 1320 1505 1840

Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.

Factory default setting.

NOTES - The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage HEAT. First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 450 cfm. Lennox iHarmony® Zoning System Applications - Minimum blower speed is 450 cfm.

First Stage Heating Speed - cfm Second Stage Heating Speed - cfm

COOLING

First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm

Page 38

TABLE 15

OPERATING SEQUENCE

SL280UHV, Non-Communicating Thermostat with Humidity Control Feature and Single-Speed Outdoor Unit

OPERATING SEQUENCE SYSTEM DEMAND SYSTEM RESPONSE

System

Condition

NO CALL FOR DEHUMIDIFICATION

Normal Operation 1 On On On Acceptable

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

Dehumidication

call

PRECISION MODE (operates independent of a Y1 demand)

Normal Operation 1 On On On Acceptable

Dehumidication

Call

Dehumidication

Call Only

Dave Lennox ComfortSense® 7000 thermostat to use for this application - Y2081 4 heat / 2 cool

*Dehumidication blower speed is 70% of COOL speed for all units .

**In Precision mode, ComfortSense® 7000 thermostat will maintain room temperature up to 2 °F (1.2°C) cooler than room setting.

Step

2 On On On Demand 0 VAC High 70%

1 On On On Demand 0 VAC High 70%

Jumpers at indoor unit with a single stage outdoor unit. With Condensing unit

- Cut W914 (R to DS) on SureLight® control With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight® control

Thermostat Demand Relative Humidity

Y1 O G W1 Status D

VAC

Compre

ssor

High 100%

Blower

CFM

(cool)

Comments

Compressor and indoor blower follow thermostat demand

ComfortSense® 7500

thermostat energizes

Y1 and de-energizes

D on a call for de-

humidication

Dehumidication

mode begins when humidity is greater

than set point

ComfortSense® 7500 thermostat

will try to maintain

room humidity

setpoint by allowing

the room space to

maintain a cooler

room thermostat

setpoint**

Page 39

TABLE 16

OPERATING SEQUENCE

SL280UHV, Non-Communicating Thermostat with Humidity Control Feature and Two-Speed Outdoor Unit

OPERATING

SEQUENCE

System

Condition

Step

NO CALL FOR DEHUMIDIFICATION

Normal Operation

1 On On On Acceptable

2 On On On On Acceptable

ROOM THERMOSTAT CALLS FOR FIRST STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

Dehumidication

call

2 On On On On Demand

PRECISION MODE (operates independent of a Y1 demand)

Normal Operation 1 On On On Acceptable

Dehumidication

Call

Dehumidication

Call Only

2 On On On On Demand

1 On On On On Demand

ROOM THERMOSTAT CALLS FOR FIRST AND SECOND STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On On Acceptable

Dehumidication

Call

2 On On On On Demand

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

Dehumidication

Call

Dehumidication

Call ONLY

2 On On On On Demand

1 On On On On Demand

Jumpers at indoor unit with a two stage outdoor unit

Cut factory jumper from Y1 to Y2 or cut W915 (Y1 to Y2)

With Condensing unit - Cut W914 (R to DS) on SureLight® control

With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight® control

Dave Lennox ComfortSense® 7000 thermostat to use for this application - Y2081 4 heat / 2 cool

*Normal operation rst stage cooling blower speed is 70% COOL speed.

**Dehumidication blower speed is, reduced to 70% of COOL.

***In Precision mode, ComfortSense® 7000 thermostat will maintain room temperature up to 2 °F (1.2°C) cooler than room setting.

SYSTEM DEMAND SYSTEM RESPONSE

Thermostat Demand Relative Humidity

Y1 Y2 O G W1 W2 Status D

VAC

Compre

ssor

Low 70%

High 100%

Low 70%

High 70%

Low 70%

High 70%

High 100%

High 70%

Low 70%

High 70%

Blower

CFM

(cool)

Comments

Compressor and indoor blower follow thermostat demand

ComfortSense® 7500 thermostat energizes Y1 and de-energizes D on a

call for de-humidication

Dehumidication mode

begins when humidity is greater than set point

ComfortSense® 7500 thermostat will try to maintain room humidity setpoint by allowing the room space to maintain a cooler room thermostat setpoint**

ComfortSense® 7500 thermostat energizes Y2 and de-energizes D on a

call for de-humidication

Dehumidication mode

begins when humidity is greater than set point

ComfortSense® 7500 thermostat will try to maintain room humidity setpoint by allowing the room space to maintain a cooler room thermostat setpoint***

Page 40

Unit Star-Up

WARNING

Do not use this furnace if any part has been underwater. Immediately call a licensed professional service technician (or equivalent) to inspect the furnace and to replace any part of the control system and any gas control which has been under water.

WARNING

If overheating occurs or if gas supply fails to shut off, shut off the manual gas valve to the appliance before shutting off electrical supply.

CAUTION

Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch.

WARNING

During blower operation, the ECM motor emits energy that may interfere with pacemaker operation. Interference is reduced by both the sheet metal cabinet and distance.

2 - Set the thermostat to the lowest setting. 3 - Turn off all electrical power to the unit. 4 - This furnace is equipped with an ignition device

which automatically lights the burners. Do not try to

light the burners by hand. 5 - Remove the upper access panel. 6 - Move gas valve switch to OFF position. Do not

force. See gure 34 or 35.

7 - Wait ve minutes to clear out any gas. If you then

smell gas, STOP! Immediately call your gas supplier

from a neighbor’s phone. Follow the gas supplier’s

instructions. If you do not smell gas go to next step.

WHITE RODGERS GAS VALVE

INLET PRESSURE POST

MANIFOLD

PRESSURE TAP

HIGH FIRE ADJUSTMENT

SCREW

(under cap)

BEFORE LIGHTING smell all around the appliance area

for gas. Be sure to smell next to the oor because some gas is heavier than air and will settle on the oor. The gas

valve on the SL280UHV unit will be equipped with a gas control switch. Use only your hand to move the switch. Never use tools. If the switch will not turn or if the control switch will not move by hand, do not try to repair it.

Placing the furnace into operation:

SL280UHV units are equipped with an automatic ignition system. Do not attempt to manually light burners on these furnaces. Each time the thermostat calls for heat, the burners will automatically light. The ignitor does not get hot when there is no call for heat on units with an automatic ignition system.

WARNING

If you do not follow these instructions exactly, a re or

explosion may result causing property damage, personal injury or death.

Gas Valve Operation (Figures 34 and 35)

1 - STOP! Read the safety information at the beginning

of this section.

GAS VALV E SHOWN IN ON POSITION

FIGURE 34

HONEYWELL GAS VALVE

HIGH FIRE

INLET PRESSURE TAP

ON SIDE

GAS VALV E SHOWN IN ON POSITION

8 - Move gas valve switch to ON position. Do not force.

See gure 34 or 35.

9 - Replace the upper access panel. 10 - 10- Turn on all electrical power to to the unit. 11 - 11- Set the thermostat to desired setting.

NOTE - When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line.

ADJUSTING SCREW

(under cap)

MANIFOLD

PRESSURE

TAP ON

SIDE

FIGURE 35

Page 41

12 - If the appliance will not operate, follow the

instructions “Turning Off Gas to Unit” and call your service technician or gas supplier.

Turning Off Gas to Unit

1 - Set the thermostat to the lowest setting. 2 - Turn off all electrical power to the unit if service is to

be performed.

3 - Remove the upper access panel. 4 - Move gas valve switch to OFF position. Do not

force. See gure 34 or 35.

5 - Replace the upper access panel.

Failure To Operate

If the unit fails to operate, check the following:

1 - Is the thermostat calling for heat? 2 - Are access panels securely in place? 3 - Is the main disconnect switch closed? 4 - Is there a blown fuse or tripped circuit breaker? 5 - Is the lter dirty or plugged? Dirty or plugged lters

will cause the limit control to shut the unit off. 6 - Is gas turned on at the meter? 7 - Is the manual main shut-off valve open? 8 - Is the internal manual shut-off valve open? 9 - Is the unit ignition system in lock out? If the unit locks

out again, call the service technician to inspect the

unit for blockages. 10 - Is pressure switch closed? Obstructed ue will

cause unit to shut off at pressure switch. Check ue

and outlet for blockages. 11 - Are ame rollout switches tripped? If ame rollout

switches are tripped, call the service technician for

inspection.

Gas Pressure Adjustment

Furnace should operate at least 5 minutes before checking gas ow. Determine time in seconds for two revolutions of gas through the meter. (Two revolutions assures a more accurate time.) Divide by two and compare to time in table 17 below. If manifold pressure matches table 19

and rate is incorrect, check gas orices for proper size and

restriction. Remove temporary gas meter if installed.

NOTE - Shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.

TABLE 17

GAS METERING CLOCKING CHART

SL280

Unit

-045 80 160 200 400

-070 55 110 136 272

-090 41 82 102 204

-110 33 66 82 164

-135 27 54 68 136

Natural 1000 btu/cu ft LP 2500 btu cu/cu ft

Seconds For One Revolution

1 cu ft

dial

2 cu fr

dial

1 cu ft

Dial

2 cu ft

Dial

Supply Line Pressure

White Rodgers Gas Valve

An inlet post located on the gas valve provides access

to the supply pressure. See gure 34. Back out the 3/32

hex screw one turn, connect a piece of 5/16 tubing and connect to a manometer to measure supply pressure. See table 19 for supply line pressure.

Honeywell Gas Valve

A threaded plug on the inlet side of the gas valve provides access to the supply pressure tap. Remove the thread-

ed plug, install a eld-provided barbed tting and connect

a manometer to measure supply pressure. See table 19 for supply line pressure. Replace the threaded plug after measurements have been taken.

Manifold Pressure

NOTE - Pressure test adapter kit (10L34) is available from Lennox to facilitate manifold pressure measurement.

1 - Connect test gauge to manifold pressure post

(gure 34) or tap (gure 35) on gas valve.

2 - Ignite unit on high re and let run for 5 minutes to

allow for steady state conditions.

3 - After allowing unit to stabilize for 5 minutes, record

manifold pressure and compare to value given in table 19.

4 - If necessary, make adjustments. Figures 34 and 35

show location of high re adjustment screw.

5 - If an adjustment is made on high re, re-check

manifold pressure on low re. Do not adjust low re manifold pressure. If low re manifold pressure is more than 1/2” above or below value specied in

table 19, replace valve.

6 - Shut unit off and remove manometer as soon as an

accurate reading has been obtained. Take care to replace pressure tap plug if removed.

7 - Start unit and perform leak check. Seal leaks if

found.

IMPORTANT

For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.

Proper Combustion

Furnace should operate minimum 15 minutes with correct manifold pressure and gas ow rate before checking combustion. Table 18 shows acceptable combustion for ALL SL280UHV models. The maximum carbon monoxide

reading should not exceed 100 ppm.

TABLE 18

Firing Rate CO2% For Nat CO2% For LP

High Fire 6.8 - 7.4 7.5 - 9.0

Low Fire 4.2 - 5.7 5.0 - 6.0

Page 42

High Altitude

The manifold pressure, gas orice and pressure switch

may require adjustment or replacement to ensure proper operation at higher altitudes. Tables 19 through 22 shows manifold pressure, pressures switch and gas conversion kits at all altitudes.

TABLE 19

Manifold Pressure Settings

Manifold

Unit

Input

070

090

110

135

This is the only permissible derate for these units.

Natural gas high altitude orice kit required.

A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion

procedure.

NOTE - Units may be installed at altitudes up to 4500 ft. above sea level without modications.

Gas

Natural .063 .055. 1.7 3.5 1.6 3.4 1.7 3.5 4.5 13.0

LP/propane

Natuarl .063 .055 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0

LP/propane

Natural .063 .055 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0

LP/propane

Natuarl .063 .055 1.7 3.5 1.6 2.8 1.7 3.5 4.5 13.0

LP/propane

Orice Size

0 - 7500 ft.

.034 .032 4.9 10.0 4.9 10.0 4.9 10.5 11.0 13.0

.034 .032 4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0

.034 .032 4.9 10.0 4.9 10.0 4.9 10.0 11.0

Orice Size 0 - 7500 ft

Pressure in. wg.

0 - 4500 ft

Low Firer

High

Fire

Manifold

Pressure in. wg.

4500 - 7500 ft

Low Fire

High

Fire

Manifold Pressure

in. wg. 7500 -

10,000 ft

Low

Fire

High

Fire

Supply Line

Min Max

Pressure

in. w.g.

TABLE 20

Unit

Input

0 - 4500 ft. 4501 - 7500 ft. 7501 - 10,000 ft.

High Altitude Pressure Switch Kit

070 No Change No Change 73W35

090 No Change 69W56 73W35

110 No Change 69W56 73W35

135 No Change 73W33 73W34

TABLE 21

Honeywell Gas Valve Conversion Kits

High

Altitude

Unit

Input

Natural Gas

Orice Kit

7501 -

10,000 ft

070 73W37 51W02 73W38 69W79

090 73W37 51W02 73W38 69W79

110 73W37 51W02 73W38 69W79

135 73W37 51W02 73W38 69W79

Natural Gas to LP/

Propane Kit

0 - 7500 ft7501 -

10,000 ft

LP/Propane

to Natural

Gas Kit

0 - 7500 ft

Unit

Input

070

090

110

135

TABLE 22

White Rodgers Gas Valve Conversion Kits

High Altitude

Natural Gas

Orice Kit

7501 - 10,000 ft

73W37 11K51 11K46 77W09

Natural Gas to LP/

Propane Kit

0 - 7500 ft7501 -

10,000 ft

to Natural

0 - 7500 ft

LP/

Propane

Gas Kit

Page 43

Other Unit Adjustments

Primary and Secondary Limits

The primary limit is located on the heating compartment vestibule panel. The secondary limits (if equipped) are located in the blower compartment, attached to the back side of the blower. These auto reset limits are factory set and require no adjustment.

Flame Rollout Switches (Two)

These manually reset switches are located on the inside of the the burner box. If tripped, check for adequate combustion air before resetting.

Pressure Switches

The pressure switch assembly (includes two switches) is located in the heating compartment adjacent to the combustion air inducer. These switches check for proper combustion air inducer operation before allowing ignition trial. The switches are factory-set and require no adjustment.

Temperature Rise

Place the unit into operation with a second-stage heating demand. After supply and return air temperatures have stabilized, check the temperature rise. If necessary, adjust the heating blower speed to maintain the temperature rise within the range shown on the unit nameplate. Increase the blower speed to decrease the temperature rise. Decrease the blower speed to increase the temperature rise. Failure to properly adjust the temperature rise may cause erratic limit operation.

Thermostat Heat Anticipation

Set the heat anticipator setting (if adjustable) according to the amp draw listed on the wiring diagram that is attached to the unit.

NOTE - Do not secure the electrical conduit directly to the air ducts or structure.

Heating Sequence of Operation

Electronic Ignition

The two-stage, variable speed integrated control used in SL280UHV units has an added feature of an internal Watchguard control. The feature serves as an automatic reset device for ignition control lockout caused by ignition failure. After one hour of continuous thermostat demand for heat, the Watchguard will break and remake thermostat demand to the furnace and automatically reset the control to begin the ignition sequence.

NOTE - The ignition control thermostat selection DIP switch is factory-set in the “TWO-STAGE” position.

Applications Using a Two-Stage Thermostat

See gure 36 for ignition control sequence

A - Heating Sequence Integrated Control Thermostat Selection DIP Switch 1 OFF in “Two-Stage”Position (Factory Setting)

1 - On a call for heat, thermostat rst-stage contacts

close sending a signal to the integrated control. The integrated control runs a self-diagnostic program and checks high temperature limit switches for normally closed contacts and pressure switches for normally open contacts. The combustion air inducer is energized at low speed.

2 - Once the control receives a signal that the low

pressure switch has closed, the combustion air inducer begins a 15-second pre-purge in low speed.

NOTE - If the low re pressure switch does not close the combustion air inducer will switch to high re. After a 15 second pre-purge the high re pressure switch will close and the unit will begin operation on high re. After 10 to 20 seconds of high re operation the unit will switch to low re.

3 - After the pre-purge is complete, a 20-second initial

ignitor warm-up period begins. The combustion air inducer continues to operate at low speed.

4 - After the 20-second warm-up period has ended,

the gas valve is energized on low re (rst stage)

and ignition occurs. At the same time, the control module sends a signal to begin an indoor blower 30-second ON-delay. When the delay ends, the

indoor blower motor is energized on the low re

heating speed, the HUM contacts close energizing

the humidier and 120V ACC terminal is energized.

The furnace will continue this operation as long as

the thermostat has a rst-stage heating demand.

5 - If second-stage heat is required, the thermostat

second- stage heat contacts close and send a signal to the integrated control. The integrated control initiates a 30-second second-stage recognition delay.

6 - At the end of the recognition delay, the integrated

control energizes the combustion air inducer at

high speed. The control also checks the high re

(second stage) pressure switch to make sure it is

closed. The high re (second stage) gas valve is

energized and the indoor blower motor is energized

for operation at the high re heating speed.

7 - When the demand for high re (second stage) heat

is satised, the combustion air inducer is switched to the low-re heating speed and the high-re (second stage) gas valve is de-energized. The low-re (rst

stage) gas valve continues operation. The indoor

blower motor is switched to the low-re heating speed.

8 - When the thermostat demand for low-re (rst

stage) heat is satised, the gas valve is deenergized and the eld-selected indoor blower off

delay begins. The combustion air inducer begins a 5-second post-purge period.

9 - When the combustion air post-purge period is

complete, the inducer, the HUM contacts as well as the 120V ACC terminals are de-energized. The indoor blower is de-energized at the end of the off delay.

Page 44

Applications Using A Single-Stage Thermostat

1 stg heat demand

2 stg heat demand

OFF

low speed CAI

Pre-Purge

Ignitor Warm-up

30* second

blower

“on” delay

Post

Purge

5 SEC80

ignitor

HEATING OPERATION WITH TWO-STAGE THERMOSTAT

low fire gas valve

indoor blower low heat

high speed CAI high fire gas valve

indoor blower high heat

Trial For Ignition

blower

“off”

delay

RECOGNITION PERIOD

30 seconds

* Conventional thermostat 30 seconds, icomfort Touch® thermostat set for 30 adjustable 15 to 45 seconds.

heat demand

OFF

low speed CAI

Pre-Purge

Ignitor Warm-up

30* second

blower

“on” delay

Post

Purge

5 SEC

ignitor

HEATING OPERATION WITH SINGLE STAGE THERMOSTAT

low fire gas valve

high speed CAI high fire gas valve

indoor blower high heat

Trial For Ignition

7 or 12 minutes after heating demand begins, furnace switches to high fire (depends on setting)

blowe

“off”

delay

indoor blower low heat

* Conventional thermostat 30 seconds, icomfort Touch

thermostat set for 30 adjustable 15 to 45 seconds.

See gure 37 for ignition control sequence

B - Heating Sequence -- Integrated Control Thermostat Selection DIP Switch 1 ON in “Single-Stage” Position

NOTE - In these applications, two-stage heat will be initiated by the integrated control if heating demand has not been satised after the eld adjustable period (7 or 12 minutes).

1 - On a call for heat, thermostat rst-stage contacts

2 - Once the control receives a signal that the low pressure

switch has closed, the combustion air inducer begins

a 15-second pre-purge in low speed

NOTE - If the low re pressure switch does not close

the combustion air inducer will switch to high re. After a 15 second pre-purge the high re pressure switch will close and the unit will begin operation on high re. After 10 to 20 seconds of high re operation the unit will switch to low re.

3 - After the pre-purge is complete, a 20-second initial

ignitor warm-up period begins. The combustion air inducer continues to operate at low speed

4 - After the 20-second warm-up period has ended, the

gas valve is energized on low re (rst stage) and

ignition occurs. At the same time, the control module sends a signal to begin an indoor blower 30-second ON-delay. When the delay ends, the indoor blower

motor is energized on the low re heating speed

and the HUM contacts are energized. The integrated control also initiates a second-stage on delay (factoryset at 7 minutes; adjustable to 12 minutes).

5 - If the heating demand continues beyond the

secondstage on delay, the integrated control energizes the combustion air inducer at high speed.

The control also checks the high re (second stage) pressure switch to make sure it is closed. The high re

(second stage) gas valve is energized and the indoor

blower motor is energized for operation at the high re

heating speed.

6 - When the thermostat heating demand is satised, the

combustion air inducer begins a 5-second low speed

post-purge. The eld-selected indoor blower off delay begins. The indoor blower operates at the low-re

heating speed.

7 - When the combustion air post-purge period is

complete, the inducer, the HUM contacts as well as the 120V ACC terminals are de-energized. The indoor blower is de-energized at the end of the off delay.

FIGURE 36

FIGURE 37

Page 45

Service

WARNING

ELECTRICAL SHOCK, FIRE,

OR EXPLOSION HAZARD.

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

Improper servicing could result in dangerous operation, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace.

When servicing controls, label all wires prior to disconnecting. Take care to reconnect wires correctly.

Verify proper operation after servicing.

WARNING

The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal injury or death.

Annual Furnace Maintenance

At the beginning of each heating season, and to comply with the Lennox Limited Warranty, your system should be

checked by a licensed professional technician (or equivalent) as follows:

1 - Check wiring for loose connections, voltage at

indoor unit and amperage of indoor motor.

2 - Check the condition of the belt and shaft bearings

if applicable. 3 - Inspect all gas pipe and connections for leaks. 4 - Check the cleanliness of lters and change if

necessary (monthly). 5 - Check the condition and cleanliness of burners and

heat exchanger and clean if necessary. 6 - Check the cleanliness of blower assembly and

clean the housing, blower wheel and blower motor

if necessary . The blower motors are prelubricated

for extended bearing life. No further lubrication is

needed. 7 - Inspect the combustion air inducer and clean if

necessary. 8 - Evaluate the heat exchanger integrity by inspecting

the heat exchanger per the AHRI heat exchanger

inspection procedure. This procedure can be

viewed at www.ahrinet.org.

9 - Ensure sufcient combustion air is available to the

furnace. Fresh air grilles and louvers (on the unit and in the room where the furnace is installed) must be properly sized, open and unobstructed to provide combustion air.

10 - Inspect the furnace venting system to make sure

it is in place, structurally sound, and without holes, corrosion, or blockage. Vent system must be free and clear of obstructions and must slope upward away from the furnace . Vent system should be installed per the National Fuel Gas Code

11 - Inspect the furnace return air duct connection to

ensure the duct is sealed to the furnace. Check for air leaks on supply and return ducts and seal where necessary.

12 - Check the condition of the furnace cabinet insulation

and repair if necessary.

13 - Perform a complete combustion analysis during the

furnace inspection to ensure proper combustion and operation. Consult Service Literature for proper combustion values.

14 - Verify operation of CO detectors and replace

batteries as required.

Perform a general system test. Turn on the furnace to check operating functions such as the start-up and shutoff operation.

1 - Check the operation of the ignition system, inspect

and clean ame sensor. Check microamps before

and after. Check controls and safety devices (gas

valve, ame sensor, temperature limits). Consult

Service Manual for proper operating range. Thermal

Limits should be checked by restricting airow and

not disconnecting the indoor blower. For additional details, please see Service and Application Note H049.

2 - Verify that system total static pressure and airow

settings are within specic operating parameters.

3 - Clock gas meter to ensure that the unit is operating

at the specied ring rate. Check the supply

pressure and the manifold pressure. On two-stage gas furnaces check the manifold pressure on high

re and low re. If manifold pressure adjustment is

necessary, consult the Service Literature for unit

specic information on adjusting gas pressure.

Not all gas valves are adjustable. Verify correct temperature rise.

Page 46

Cleaning the Burners

NOTE - Use papers or protective covering in front of the furnace during cleaning.

1 - Turn off both electrical and gas power supplies to

furnace.

2 - Label the wires from gas valve, rollout switches,

primary limit switch and make-up box then

disconnect them. 3 - Disconnect gas supply piping. Remove the screw

securing the burner box cover and remove cover.

Remove the four screws securing the burner

manifold assembly to the vestibule panel and

remove theassembly from the unit.

SL280UHV BURNER ASSEMBLY AND REMOVAL

4 - To clean burners, run a vacuum cleaner with a soft

brush attachment over the face of burners. Visually inspect inside the burners and crossovers for any blockage caused by foreign matter. Remove any blockage. Figure 38 shows burner detail.

5 - Reinstall burner box, manifold assembly and burner

box cover.

6 - Re-install gas supply and turn on electrical pwer to

furnace.

Ignitor

Sensor

Rolllout Switches

Manifold And Gas Valve

Burner Detail Front View

Cross Over

Retention Rings

FIGURE 38

Page 47

Repair Parts List

The following repair parts are available through independent Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA International nameplate -- Example: SL280UH070V36A. All service must be

performed by a licensed professional installer (or equivalent), service agency, or gas supplier.

Cabinet Parts

Upper access panel Blower panel Top cap

Control Panel Parts

Transformer Two-stage, variable speed integrated control Door interlock switch Circuit breaker

Blower Parts

Blower wheel Blower housing Motor Motor electronics Power choke (1 hp only) Motor mounting frame Motor capacitor Blower housing cutoff plate

Heating Parts

Flame Sensor Heat exchanger assembly Gas manifold Two-speed combustion air inducer Two-stage gas valve Main burner cluster

Main burner orices

Pressure switch Ignitor Primary limit control Flame rollout switch Secondary limit

Page 48

Integrated Control Diagnostic Modes

Display Action (when button is released)

No change (idle)* Remain in idle mode

Solid “E” Enter diagnostic recall mode

Solid “D” Discharge Air Installed

Solid “F” Enter ame signal mode

Solid “F” (variable speed only) Program unit capacity size (Unit Code)

Two horizontal lines soft disable

* No change implies the display will continue to show whatever is currently being displayed for normal operation (blinking decimal, active error code, heat state, etc..)

Diagnostic LED (Figure 33) The seven-segment diagnostic LED displays operating

status, target airow, error codes and other information.

The table beginning on the next page lists diagnostic LED codes.

Diagnostic Push Button (Figure 33)

menu of options. Every ve seconds a new menu item will

be displayed. When the button is released, the displayed item will be selected. Once all items in the menu have been displayed, the menu resumes from the beginning until the button is released.

Error Code Recall Mode

Select ”E” from the menu to access the most recent 10 error codes. Select “c” from the Error Code Recall menu to clear all error codes. Button must be pressed a second

time while “c” is ashing to conrm command to delete codes Press the button until a solid “≡” is displayed to exit

the Error Code Recall mode.

Flame Signal Mode

Select ”F” from the menu to access the ame signal mode. The integrated control will display the ame current on 7

segment LED in in micro amps (uA). Flame signal mode is exited after any of the following:

• Power is reset

• Pressing and holding push button until 3 horizontal

Program Unit Capacity/Size Mode

After the “P” is selected (by releasing the push button)

the integrated control will start ashing the “P” on display

for 90 seconds. If push button is pressed again and held during that time, the control will start to display characters corresponding to different variable speed furnace models for 3 seconds each. While the wanted character-model is displayed push button has to be released. Selected option

will ash display for 10 seconds and during that time push

button has to be pressed and held for 5 seconds. Once control accepts new setting it will store data in non-volatile memory and reset itself. If 10 seconds expires or push

button is held less than 5 seconds, control will exit eld

test mode and go into idle without changing programming the unit size.

Soft Disable

Soft disabling is when thermostat nds a device on the

BUS that it does not recognize and the thermostat sends a the device a message to be in soft disabling mode until

properly congured. Two horizontal bars will display.

Steps to follow if the damper control module is displaying the soft disable code.

1 - Conrm proper wiring between all devices

(thermostat, damper control module, indoor and outdoor).

2 - Cycle power to the control that is displaying the soft

disable code. 3 - Put the room thermostat through set up. 4 - Go to setup / system devices / thermostat / edit /

then push reset. 5 - Go to setup / system devices / thermostat / edit /

then push resetAll.

lines “≡” are displayed

• 10 minutes after entering the ame sense mode.

Page 49

Integrated Control Diagnostic Modes

Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover

. Idle mode (Decimal blinks at 1 Hertz -- 0.5

second ON, 0.5 second OFF).

A Cubic feet per minute (cfm) setting for

indoor blower (1 second ON, 0.5 second OFF) / cfm setting for current mode displayed.

C Cooling stage (1 second ON, 0.5 second

OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes).

d Dehumidication mode (1 second ON) /

1 second OFF) / cfm setting displayed / Pause / Repeat Codes).

h Heat pump stage (1 second ON, 0.5

second OFF) / % of input rate displayed / Pause / cfm setting / Pause / Repeat codes.

H Gas Heat Stage (1 second ON, 0.5 second

OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes. Blinking during ignition.

dF Defrost mode.

U Discharge Air Temperature

E105 Device communication problem - No other

devices on RS BUS (Communication system).

E110 Low line voltage. Line Voltage Low (Voltage lower than nameplate rating). Check power line

E111 Low line voltage. Reverse line power voltage wiring. System resumes normal operation 5

E112 Ground not detected System shuts down. Provide proper earth ground. System resumes normal

E113 High line voltage. Line Voltage High (Voltage higher than nameplate rating). Provide power

E114 Line voltage frequency out-of-range. No 60 Hertz Power. Check voltage and line power frequency. Correct

E115 Low 24V - Control will restart if the error

recovers.

E116 High 24V. 24 Volt Power High (Range is 18 to 30 volts). Check and correct voltage.

E117 Poor ground detected (Warning only) Provide proper grounding for unit. Check for proper earth ground to the

E120 Unresponsive device. Communication

only.

Equipment is unable to communicate. Indicates numerous message errors. In most cases errors are related to electrical noise. Make sure high voltage power is separated from RSBus. Check for miswired and/or loose connections between the stat, indoor unit and outdoor unit. Check for a high voltage source of noise close to the system. Fault clears after communication is restored.

voltage and correct. Alarm clears 5 seconds after fault recovered.

seconds after fault recovered.

operation 5 seconds after fault recovered.

voltage within proper range. System resumes normal operation 5 seconds after fault recovered.

voltage and frequency problems. System resumes normal operation 5 seconds after fault recovered.

24-Volt Power Low (Range is 18 to 30 volts). Check and correct voltage. Check for additional power-robbing equipment connected to system. May require installation of larger VA transformer to be installed in furnace / air handler. Clears after fault recovered.

Check for proper line voltage (120V, 240V, etc.) to equipment. Clears when control senses proper voltage.

system. Warning only will clear 30 seconds after fault recovered.

Usually caused by delay in outdoor unit responding to indoor unit poling. Recycle power. Check all wiring connections. Cleared after unresponsive device responds to any inquiry.

Page 50

Integrated Control Diagnostic Modes

Code

E124 Active communicating thermostat signal

Diagnostic Codes/Status of Equipment Action Required to Clear and Recover

Equipment lost communication with the thermostat. Check

missing for more than 3 minutes.

four wiring connections, ohm wires and cycle power at the thermostat. Alert stops all services and waits for heartbeat message from thermostat (subnet controller). Cleared after valid thermostat (subnet controller) message is received.

E125 Control failed self-check, internal error,

failed hardware. Will restart if error recovers. Integrated control not communicating.

Hardware problem on the control. Cycle power on control. Replace if problem prevents service and is persistent. Criti-

cal alert. Cleared 300 seconds after fault recovered. Covers hardware errors (ame sense circuit faults, pin shorts, etc.).

E126 Control internal communication problem. Hardware problem on the control. Cycle power on con-

trol. Replace if problem prevents service and is persistent.

Cleared 300 seconds after fault recovered.

E131 Corrupted control parameters (Verify con-

guration of system). Communicating only.

Recongure the system. Replace control if heating or cool-

ing is not available. Only applicable in the communicating

mode, not in startup. Exit from Commissioning and Execute

‘Set Factory Default mode Control will still operate on default

parameter settings

E180 Outdoor air temperature sensor failure.

Only shown if shorted or out-ofrange.

Compare outdoor sensor resistance to temperature/ resis-

tance charts in unit installation instructions. Replace sensor

pack if necessary. At beginning of (any) conguration, furnace

or air handler control will sense outdoor air and discharge

air temperature sensor(s). If detected (reading in range),

appropriate feature will be set as ‘installed’ and that could

be seen in ‘About’ screen. In normal operation after control

recognizes sensors, alarm will be sent if valid temperature

reading is lost. To get rid of setting and alarm, redo congu-

ration and make sure that temperature sensor is marked as

‘not installed’ in Indoor Unit ‘About’ screen. When Indoor unit

control is replaced, thermostat will ‘tell’ new control if tem-

perature sensor is in system or not. Clears 30 seconds after

fault recovered.

E200 Hard lockout - Rollout circuit open or pre-

viously open.

E201 Indoor blower communication failure - Un-

able to communicate with blower motor.

Correct cause of rollout trip, or replace ame rollout switch.

Test furnace operation. Cleared after fault recovered.

Indoor blower communication failure (including power out-

age). Lost communication with indoor blower motor. Possible

causes: motor not powered, loose wiring. Problem may be

on control or motor side. Cleared after fault recovered.

E202 Indoor blower motor mis-match - Indoor

motor horsepower does not match unit capacity.

Incorrect appliance capacity code selected. Check for proper

conguring under: Unit Size Codes for Furnace/Air Handler

on conguration guide or in installation instructions. Cleared

after the correct match is detected following a reset. (Re-

move thermostat from system while applying power and re-

programming.)

E203 Appliance capacity / size is NOT pro-

grammed. Invalid unit codes refer to con-

guration ow chart.

No appliance capacity code selected. Check for proper con-

guring under: Unit Size Codes for Furnace on conguration

guide or in installation instructions. Critical Alert. Cleared af-

ter valid unit code is read following a reset. (Remove thermo-

stat from system while applying power and reprogramming.)

E204 Gas valve mis-wired. Check gas valve operation and wiring. Clears when repaired.

E205 Gas valve control relay contact shorted. Check wiring on control and gas valve. If wiring is correct,

replace control.

Page 51

Integrated Control Diagnostic Modes

Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover

E206 Gas valve second-stage relay failure Furnace will operate on 1st stage for remainder of the

heating demand. Will clear after fault recovered. If unable to operate 2nd stage, replace control.

E207 Hot surface ignitor sensed open. Measure resistance of hot surface ignitor. Replace if

open or not within specied range found in IOM. Resumes normal operation after fault is cleared.

E223 Low pressure switch failed open. Check pressure (inches w.c.) of low pressure switch

closing on heat call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared

E224 Low pressure switch failed closed. Check operation of low pressure switch to see if it is

stuck closed on heat call longer than 150 seconds. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared.

E225 High pressure switch failed open. Check pressure (inches w.c.) of high pressure switch

closing on heat call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared.

E226 High pressure switch failed closed Check operation of high pressure switch closing on heat

call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared.

E227 Low pressure switch open during trial for ignition

or run mode.

Check pressure (inches w.c.) of low pressure switch closing on heat call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared.

E228 Combustion air inducer calibration failure Unable to perform pressure switch calibration. Check

vent system and pressure switch wiring connections. Resumes normal operation after fault is cleared.

E229 Ignition on high re IFC switched to high re ignition because low re pres-

sure switch did not close in allowed time. No action is needed.

E240 Low ame current - Run mode. Check micro-amperes of ame sensor using control

diagnostics or eld-installed mode. Clean or replace

sensor. Measure voltage of neutral to ground to ensure good unit ground. Alert clears after current heat call has been completed.

E241 Flame sensed out of sequence - Flame still pres-

ent.

Shut off gas. Check for gas valve leak. Replace, if necessary. Alert clears when fault is recovered.

E250 Limit switch circuit open. Check for proper ring rate on furnace. Ensure there is

no blockage in heater. Check for proper air ow. If limit

not closed within 3 minutes, unit will go into 1-hour soft lockout. Resumes normal operation after fault is cleared.

E252 Discharge air temperature too high (gas heat only). Check temperature rise, air ow and input rate. Cleared

when heat call is nished.

E270 Soft lockout - Exceeded maximum number of re-

tries. No ame current sensed.

Check for proper gas ow. Ensure that ignitor is lighting burner. Check ame sensor current. Clears when heat call nishes successfully.

Page 52

Integrated Control Diagnostic Modes

Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover

E271 Soft lockout - Exceeded maximum number of re-

tries. Last retry failed due to the pressure switch opening.

E272 Soft lockout - Exceeded maximum number of re-

cycles. Last recycle due to the pressure switch opening.

Check operation of low pressure switch to see if it is stuck closed on heat call. Check pressure (inches w.c.) of high pressure switch closing on heat call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Clears when

heat call nishes successfully.

E273 Soft lockout - Exceeded maximum number of re-

cycles. Last recycle due to ame failure.

Check micro-amperes of ame sensor using control diagnostics or eld-installed mode. Clean or replace sensor.

Measure voltage of neutral to ground to ensure good unit

ground. Clears when heat call nishes successfully.

E274 Soft lockout - Exceeded maximum number of re-

cycles. Last recycle failed due to the limit circuit opening or limit remained open longer than 3 min-

Shut down system. 1-hour soft lockout. Check ring rate and air ow. Check for blockage. Clears when heat call nishes successfully.

utes

E275 Soft lockout - Flame sensed out of sequence.

Flame signal is gone.

Shut off gas. Check for gas valve leak. 1-hour soft lockout.

Clears when ame has been proven stable.

E276 Watchguard calibration failure. Unable to perform pressure switch calibration. Check vent

system and pressure switch wiring connections. 1-hour soft

lockout. Clears when calibration has nished successfully.

E290 Ignitor circuit fault - Failed ignitor or triggering cir-

cuitry.

Measure resistance of hot surface ignitor. Replace if open

or not within specications. 1-hour soft lockout. Clears when ame has been proven stable.

E291 Heat air ow restricted below the minimum. Check for dirty lter and air ow restriction. Check blower

performance. 1-hour soft lockout. Cleared when heat call

nishes successfully.

E292 Indoor blower motor unable to start due to ob-

structed wheel, seized bearings.

Indoor blower motor unable to start (seized bearing, stuck wheel, etc.). Replace motor or wheel if assembly does not operate or meet performance standards. 1-hour soft lockout. Clears after circulator successfully starts.

E294 Combustion air inducer over current. Check combustion blower bearings, wiring and amps. Re-

place if does not operate or does not meet performance standards. Clears after inducer current is sensed to be inrange after the ignition following the soft lockout or reset.

E295 Indoor blower motor temperature is too high. Indoor blower motor over temperature (motor tripped on

internal protector). Check motor bearings and amps. Replace if necessary. Cleared after blower demand is satis-

ed.

E310 Discharge error temperature sensor failure. Only

shown if shorted or out of range.

Compare outdoor sensor resistance to temperature/ resistance charts in installation instructions. Replace sensor if necessary. Cleared in Communicating mode: 30 seconds after fault recovered. In Non- Communicating mode: Cleared after the current heat call is completed.

E311 Heat rate reduced to match indoor blower air ow. Warning Only. Furnace blower in cutback mode due to

restricted airow. Reduce ring rate every 60 seconds to match available CFM. Check lter and duct system. To clear, replace lter if needed or repair/ add duct. 2-stage controls will reduce ring rate to 1st stage. Clears when heat call nishes successfully.

Page 53

Integrated Control Diagnostic Modes

Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover

E312 Restricted air ow in cooling or continu-

ous fan mode is lower than cfm setting.

Warning Only. Restricted airow - Indoor blower is running at a reduced CFM (Cutback Mode - The variable speed motor has pre-set speed and torque limiters to protect the motor from damage caused by operating outside of design parameters (0 to 0.8” W.C.. total ex-

ternal static pressure). Check lter and duct system. To clear, replace lter if needed or repair/add duct. Cleared after the current service demand is satised.

E313 Indoor or outdoor unit capacity mismatch.

Communication only.

Incorrect indoor/outdoor capacity code selected. Check for proper

conguring in installation instructions. Alarm is just a warning. The system will operate, but might not meet efciency and capacity pa-

rameters. Alarm will clear when commissioning is exited. Cleared after commissioning is complete.

E331 Global network connection - Communica-

For Future Use.

tion link problem.

E334 Relay “Y1” stuck on interated control. Replace integrated control.

E347 No 24 Volt output on Y1 of ”integrated

control” with non communicating outdoor unit.

E348 No 24 Volt output on Y2 of ”integrated

control” with non?communicating outdoor unit.

E349 No 24 Volts between R & O on ”integrated

control” with non communicating outdoor

Operation stopped. Y1 relay / Stage 1 failed. (Pilot relay contacts did not close or the relay coil did not energize; no input back to IFC chip). Critical Alert. Cleared after reset and Y1 input sensed.

Y2 relay / Stage 2 failed. (Pilot relay contacts did not close or the relay coil did not energize; no input back to IFC chip). Critical Alert. Cleared after reset and Y1 input sensed.

Conguration link R to O needs to be restored. Replace link or hard-

wire. Applicable in non communicating mode. Critical Alert. unit (Dual fuel module required for heat pump application

E370 Interlock switch sensed open for 2 min-

utes.

Control sees the loss of 24VAC for 2 minutes.Terminate all services

and wait for interlock switch to close. The alarm will clear when

24VAC is continuously sensed on DS terminal for a minimum of 10

seconds or on a power reset.

E400 LSOM - Compressor internal overload

tripped.

Thermostat demand Y1 is present; but, compressor is not running.

Check power to outdoor unit. Clears the error after current is sensed

in both RUN and START sensors for at least 2 seconds, or after

service is removed, or after power reset.

E401 LSOM Compressor long run cycle or low

system pressure.

Compressor ran more than 18 hours to satisfy a single thermostat

demand. Critical Alert. Clears the error after 30 consecutive normal

run cycles or power reset. Also monitors low pressure switch trips.

E402 LSOM - Outdoor unit system pressure

trip.

Discharge or suction pressure out-of-limits, or compressor over-

loaded. Clears the error after 4 consecutive normal compressor run

cycles.

E403 LSOM - Compressor short-cycling. .(Run-

ning less than 4 minutes). Outdoor unit pressure trip

E404 LSOM - Compressor rotor locked. Com-

pressor short-cycling. (Running less than 4 minutes).

Compressor runs less than 3 minutes to satisfy a thermostat de-

mand. Clears the error after 4 consecutive normal run cycles or

power reset.

Compressor rotor locked up due to run capacitor short, bearings

are seized, excessive liquid refrigerant, etc. Clears the error after 4

consecutive normal run cycles or after power reset.

E405 LSOM - Compressor open circuit. Compressor circuit open (due to power disconnection, open fuse,

etc.) Clears the error after 1 normalcompressor run cycle.

Page 54

Integrated Control Diagnostic Modes

Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover

E406 LSOM - Compressor open start circuit. Required amount of current is not passing through Start cur-

rent transformer. Clears the error after current is sensed in START sensor, or after power reset.

E407 LSOM - Compressor open run circuit. Required amount of current is not passing through Run current

transformer. Clears the error after current is sensed in RUN sensor, or 1 normal compressor run cycle, or after power reset.

E408 LSOM - Compressor contactor is welded. Compressor runs continuously. Clears the error after 1 normal

compressor run cycle or after power reset.

E409 LSOM - Compressor low voltage. Secondary voltage is below 18VAC. After 10 minutes, oper-

ation is discontinued. Clears the code after voltage is higher than 20 VAC for 2 seconds or after power reset.

Program Unit Capacity / Size Mode

Power-Up - Number displayed represents by integrated control unit size code (furnace model and capacity). If three horizontal bars are displayed followed by continuous E203, furnace control does not recognize unit size code. Configure per the following:

Yes

To enter Program Unit Capacity/Size: push and hold button next to 7-segment LED display until solid “P” symbol appears. Release button.

IMPORTANT: Field replacement controls may need to be manually configured to validate furnace unit size code.

Solid P starts blinking on 7-Segment LED

Push and hold button. Integrated control will display unit size code number for each furnace model for three seconds.

Furnace control in IDLE mode

No heating, cooling or indoor fan

operation)

−

Turn room thermostat to OFF

UNIT SIZE

CODE

FURNACE MODEL

SL280UH070V36A

SL280UH090V36B

SL280UH090V48B

SL280UH090V60C

SL280UH110V60C

SL280UH135V60D

When the correct unit size code is displayed, release button. Selected code will flash for 10-second period. During that period, press and hold push button for 5 seconds. Integrated control will store code in memory and will automatically exit Program Unit Capacity/Size Mode and reset. (If second period expires or push button is held less than five seconds, control will automatically exit Program Capacity/Size Mode and go into IDLE mode without storing unit size code. If this happens, programming function must be repeated).

UNIT SIZE

CODE

FURNACE MODEL

SL280DF070V36A

SL280DF090V48B

SL280DF090V60C

SL280DF110V60C

FINISHED

Page 55

Verify that the selected unit size code is correct and stored in non-volatile memory by cycling the 24 volt power to the furnace control. (At 24 volt power-up of the furnace control, the 7-segment LED will display a unit size code three horizontal bars display, board does not recognize unit size code function must be repeated)

. Programming

. If

−

Troubleshooting: Heating Sequence of Operation

CALL FOR FIRST-STAGE HEAT

CALL FOR

1ST STAGE HEAT

(LOW FIRE)

LIMIT SWITCH

ROLLOUT

PRESSURE

INDUCER ON

LOW SPEED

PRESSURE SWITCH

CLOSED WITHIN 120

SECONDS?

PRE−PURGE

(15 SECONDS)

H.S.I. ON

(20 SECONDS)

1ST STAGE GAS

VALVE ENERGIZED

IGNITION TRIAL

BEGINS (H.S.I. ON)

HIGH

CLOSED?

YES

CIRCUITS

CLOSED?

YES

LOW

SWITCH

OPEN?

YES

LOW

YES

HEAT FAN ON DEL AY

INDOOR BLOWER OFF AFTER

HEAT FAN OFF DEL AY

(LOW HEAT SPEED)

ERROR

CODE

FLASHES

DE−ENERGIZE

GAS VALV E

ERROR CODE

FLASHES (AFTER

5 SECONDS)

LOW PRESSURE SWITCH OPENS

TIMER STARTED

INDOOR BLOWER

ON(LOW HEAT

SPEED)

HIGH

PRESSURE

SWITCH

OPEN

BEFORE

INDUCER WAS

TURNED ON?

INDUCER ON

(HIGH SPEED)

INDOOR BLOWER ON (LOW HEAT

SPEED)

INTERPURGE

(15 SECONDS)

YES

LIMIT

SWITCH

CLOSED WITHIN 3

MINUTES?

ERROR

CODE

FLASHES

INDUCER TO

HIGH SPEED−

ERROR CODE

FLASHES

BLOWER OFF

AFTER HEAT FA N

OFF DELAY (LOW

ROLLOUT

CIRCUIT CLOSES

(MANUAL

RE−SET)

INDOOR BLOWER OFF AFTER HEAT OFF DELAY

HARD LOCKOUT − ERROR CODE FLASHES

LOW & HIGH

PRESSURE SWITCH

CLOSED WITHIN 30

SECONDS?

INDOOR

HEAT SPEED)

INDUCER OFF

AFTER POST

PURGE

YES

WATCHGUARD − ERROR CODE FLASHES

YES

INDUCER OFF−

WAIT 5 MINUTES ERROR CODE

FLASHES

CALL

FOR HEAT

ENDS?

YES

INDOOR

BLOWER

ON?

YES

INDOOR

BLOWER

OFF AFTER

HEAT FA N

OFF DELAY

FLAME

SENSED WITHIN

4 SECONDS?

YES

H.S.I. OFF

INDOOR

BLOWER ON 30 SEC.

(LOW HEAT SPEED)

CALL FOR HEAT SATISFIED

GAS VALV E

DE−ENERGIZED

H.S.I. OFF

5TH

UNSUCCESSFUL

TRIAL?

WATCHGUARD LOCKOUT AUTOMATICALLY RESETS AFTER ONE HOUR

HARD LOCKOUT REQUIRES THERMOSTAT RESET OR CYCLING OF POWER TO RESET THE LOCKOUT.

IN CASE HIGH SPEED INDUCER IS RUNNING AT THE TIME THE GAS VA LVE GETS ENERGIZED,

2ND STAGE GAS VALVE IS ENERGIZED INSTEAD OF 1ST STAGE. 20 SECONDS AFTER FLAME IS SENSED, INDUCER SWITCHES TO LOW SPEED, AND GAS VA LVE SWITCHES TO 1ST STAGE.

YES

POSTPURGE (5 SECONDS)

INDUCER

OFF

WATCHGUARD − ERROR CODE FLASHES

Page 56

Troubleshooting: Heating Sequence of Operation (Coninued)

CALL FOR SECOND-STAGE HEAT

2 STAGE THERMOSTAT

RECOGNITION DELAY

ONLY FOR 1ST REQUEST FOR

2ND STAGE HEAT

CALL FOR 2ND STAGE HEAT

(30 SECONDS)

EXPIRED?

(HIGH FIRE)

YES

INDUCER SWITCHED

TO HIGH SPEED

HIGH

PRESSURE SWITCH

CLOSED WITHIN 10

SECONDS?

YES

2ND STAGE GAS VALVE

ENERGIZED

INDOOR BLOWER ENERGIZED

ON HIGH HEAT SPEED

SINGLE STAGE

THERMOSTAT

2ND STAGE

ON DELAY

EXPIRED?

YES

INDUCER SWITCHED

TO LOW SPEED

5 MINUTE DELAY

(ERROR CODE FLASHES)

CALL FOR HEAT SATISFIED

SYSTEM WILL ALWAYS LIGHT ON LOW FIIRE, EVEN IF 2ND STAGE HEAT IS IN PLACE.

WHEN USED WITH A SINGLE STAGE THERMOSTAT, SET SW1 TO THE ON POSITION IN DIP SWITCH S4.

IF THE HIGH FIRE PRESSURE SWITCH DOES NOT CLOSE WITHIN 5 ATTEMPTS, THE SYSTEM WILL OPERATE AT LOW FIRE FOR THE REMAINDER OF THE CALL FOR HEAT REQUEST.

Page 57

Troubleshooting: Heating Sequence of Operation (Coninued)

CALL FOR HEAT SATISFIED

FIRST-STAGE HEAT SECOND-STAGE HEAT

2 3

2ND STAGE HEAT

2ND STAGE

CALL FOR HEAT

SATISFIED?

YES

DE−ENERGIZE 2ND STAGE

GAS VALV E

RUN MODE: 1ST OR 2ND STAGE CALL FOR HEAT.

ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT/COOL, FLAME LEVEL)

INDUCER SPEED SWITCHED

TO LOW SPEED

INDOOR BLOWER SWITCHED

TO LOW HEAT SPEED

1ST STAGE HEAT

1ST STAGE

CALL FOR HEAT

SATISFIED?

YES

GAS VALV E

DE−ENERGIZED

INDUCER OFF AFTER

5 SECOND POST PURGE

INDOOR BLOWER OFF

AFTER FIELD SELECTABLE

OFF DELAY

Page 58

Troubleshooting: Cooling Sequence of Operation

CALL FOR COOLING

1ST STAGE COOLING

REQUEST RECEIVED

WAIT FOR COMPRESSOR TIMED

OFF DELAY TO EXPIRE

ENERGIZE 1ST STAGE COOLING CONTACTOR (COMPRESSOR & FAN)

INDOOR BLOWER 2 SECOND ON DELAY

ENERGIZE INDOOR BLOWER

(LOW COOLING MODE)

2ND STAGE

COOLING

REQUEST?

YES

ENERGIZE 2ND STAGE COOLING CONTACTOR (COMPRESSOR & FAN)

2ND STAGE

COOLING REQUEST

STILL ACTIVE?

MAINTAIN INDOOR

BLOWER

(LOW COOLING MODE)

YES

ENERGIZE INDOOR BLOWER

(HIGH COOLING MODE)

MAINTAIN INDOOR BLOWER

YES

1ST STAGE

COOLING REQUEST

STILL ACTIVE?

(HIGH COOLING MODE)

DE−ENERGIZE 2ND

STAGE COOLING

CONTACTOR

(COMPRESSOR & FAN)

1ST STAGE

COOLING REQUEST

STILL ACTIVE?

DE−ENERGIZE 1ST

STAGE COOLING

CONTACTOR

(COMPRESSOR & FAN)

DE−ENERGIZE INDOOR

BLOWER

YES

ENERGIZE AND MAINTAIN

INDOOR BLOWER AT

(LOW COOLING MODE)

CONTROL WILL NOT RESPOND TO A 2ND STAGE COOLING REQUEST UNLESS A 1ST STAGE COOLING REQUEST IS ACTIVE.

INDOOR BLOWER LOW COOLING MODE AND HIGH COOLING MODE HAVE SPECIFIC ON, OFF

AND SPEED RAMPING PROFILES. THE SPECIFIC PROFILE IS SELECTED USING THE

DIP SWITCHES ON THE CONROL.

Page 59

Troubleshooting: Fan Sequence of Operation

CALL FOR FAN

INDOOR BLOWER ON

CONTINUOUS FAN

SPEED

CALL FOR FAN

REMOVED?

YES

REQUEST

FOR COOLING

RECEIVED?

REQUEST

FOR HEAT

RECEIVED?

DE-ENERGIZE INDOOR

BLOWER

YES

MAINTAIN INDOOR

BLOWER AT

CONTINUOUS FAN

MAINTAIN INDOOR

BLOWER AT

CONTINUOUS FAN

INDOOR BLOWER OFF

GO TO CALL FOR COOLING

GO TO CALL FOR 1ST STAGE HEAT

Page 60

Lennox SL280135V60D, SL280UH090V48B, SL280UH110V60C, SL280UH060NV36A, SL280UH100NV60C Installation Instructions Manual

Specifications and Main Features

Frequently Asked Questions

User Manual