Lennox SL280UHNV User's Information Manual

USER’S INFORMATION

©2017 Lennox Industries Inc.

Dallas, Texas, USA

507650-01
10/2017

MANUAL

SL280UHNV
SERIES

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.

WARNING

FIRE OR EXPLOSION HAZARD.

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

Do not store or use gasoline or other ammable

vapors and liquids in the vicinity of this or any
other appliance.

Installation and service must be performed

by a qualied installer, service agency or the

gas supplier.

WHAT TO DO IF YOU SMELL GAS:

• Do not try to light any appliance.

• Do not touch any electrical switch; do not

• use any phone in your building.

• Immediately call your gas supplier from a

• neighbor’s phone. Follow the gas supplier’s

• instructions.

• If you cannot reach your gas supplier, call

• the re department.

SL280UHNV Parts Identication

Combustion Air
Inducer

Gas Valve

Combustion Air Inducer
Pressure Switch

Heat Exchanger
Assembly

Blower Motor

FIGURE 1

NOTE - This manual is the property of the homeowner

and must be left with the equipment user.

Notice to Homeowner

This furnace is equipped with safety devices that protect
you and your property. If one or more of these devices is
activated, furnace operation will stop. If your home is left
unattended for an extended period of time, equipment op­eration must be checked periodically.

Ignition Control

If this is not possible, the water supply to the house should
be shut off and the pipes should be drained. This will pre­vent problems associated with a NO HEAT condition (fro­zen pipes, etc.)

Page 2

CAUTION

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

Your furnace is a gas appliance. It is critical that the gas
supplied to the unit be completely burned to avoid the pro­duction of carbon monoxide gas. Complete combustion of
the gas requires, but is not limited to, correct gas pressure

and gas ow rate, adequate combustion air and proper

venting.

NOTICE

Any additions, changes, or conversions required in order
for the appliance to satisfactorily meet the application
needs must be made by a licensed professional installer

(or equivalent) using factory-specied and approved

parts.

Safety Instructions

1 - Keep the furnace area clear and free of combustible

material, gasoline, and other ammable vapors

and liquids. If it is installed in an insulated area, the
furnace must be kept free of insulating material.
Insulating material may be combustible.

2 - DO NOT obstruct air ow to unit. Unit must receive

an unobstructed ow of combustion and ventilating

air. DO NOT block or obstruct air openings on
the furnace or air openings to the area in which
the furnace is installed. Take care to maintain
established clearances surrounding the furnace.

3 - DO NOT store chlorine or uorine products near

unit or introduce these products into the combustion
air. These products can cause furnace corrosion.

4 - DO NOT draw return air from a room where this

furnace, or any other gas appliance (ie., a water
heater), 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 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.

WARNING

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

WARNING

Asphyxiation Hazard
The exhaust vent for this furnace must be leak-free and

must be securely connected to the furnace ue collar at

all times.

For your safety and to fulll the terms of the limited

warranty, a licensed professional service technician (or
equivalent) must annually inspect this furnace and its
vent system.

Exposure to carbon monoxide gas can cause personal
injury and even death to all occupants, including pets.
Any item that is powered by, or gives off heat from, a
combustion process (including lawn mowers, automo-

biles, and replaces) has the potential to produce carbon

monoxide gas. Because of this, Lennox recommends
the use of a carbon monoxide detector in your home,
even if you do not own gas appliances. Reliable de-

tectors are available at reasonable retail prices. Contact
your Lennox dealer for more details about this invest­ment in your safety.

Your furnace is designed to meet standards set by nation­al agencies, and to operate safely when properly installed
and maintained. However, the unit’s performance can be
greatly impacted by the individual installation and the op­erating environment. It is your responsibility to ensure that
this appliance is maintained.

Proper maintenance is critical for your safety and the sat­isfactory operation m./of the product. Lennox strongly
recommends annual inspection and maintenance of this
appliance. Contact your Lennox dealer for an inspection
by a licensed professional service technician.

Start-Up & Operation

NOTE - When the furnace begins heating mode, the di­agnostic LED on the furnace control will display “H1” for
heating operation in 1st stage, or “H2” for heating opera­tion in 2nd stage. The LED can be seen through the view-

port on the lower access panel. See gure 2.

WARNING

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

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

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 is equipped with a gas
control switch. Use only your hand to move the gas con­trol switch. Never use tools. If the switch will not move by
hand, do not try to repair it. Call a licensed professional
service technician (or equivalent). Force or attempted re-

pair may result in a re or explosion.

Page 3

HUM

GAS VALV E

GAS VALVE SHOWN IN THE ON POSITION

ACC

L1

HSI/CAI

15

J3

N

N

IGN

CAI1

CAI2

NEGATIVE AIR

PRESSURE PORT

POSITIVE AIR

PRESSURE PORT

NEUTRALS

FLAME

SENSE

123456

ON

S4S3

911

13

10

12

ON

OUTDOOR

SENSOR

DISCHARGE

AIR SENSOR

I+ I−

RI+ I− CRI+ I− C

OUTDOOR EQUIPMENT

S1

7 8

15

14

INDOOR EQUIPMENT

DIAGNOSTIC

LED

SureLight

W1W2 G Y2 Y1 CC DH LODSR

G

C

W1

W2

C

Y2

Y1



R

110

3

L

DH

14

3

4 7

CUT FOR

OPTION

SELECTION

W915

2 STAGE

COMPR

W951
HEAT

PUMP

W914

DEHUM

HARMONY

P79

6

J2

12

FIGURE 2

Placing the SL280UHNV furnace into operation:

SL280UHNV units are equipped with a SureLight® igni­tion system. Do not attempt to manually light the burner
on these furnaces. Each time the thermostat calls for heat,
the burner will automatically light.

Operating the Gas Valve (Figure 3)

1 - STOP! Read the safety information at the beginning

of this section.

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 access panel.

6 - Move switch on gas valve to OFF. Do not force. See

gure 3.

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.

8 - If you do not smell gas go to next step.

INLET

SUPPLY

PRESSURE

TAP

OUTLET

MANIFOLD

PRESSURE TAP

FIGURE 3

9 - Replace the upper access panel.

10 - Turn on all electrical power to to the unit.

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.

12 - If the appliance will not operate, follow the

instructions

Turning Off Gas to the Unit

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.

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 switch on gas valve to OFF. Do not force. See

gure 3.

5 - Replace the access panel.

WARNING

Do not set thermostat below 60°F (16°C) in heating
mode. Setting thermostat below 60°F (16°C) reduces
the number of heating cycles. Damage to the unit may
occur that is not covered by the warranty.

Filters

All SL280UHNV lters are installed external to the unit.

Filters should be inspected monthly. Clean or replace the
lter( s) when necessary to ensure proper furnace opera­tion. A lter must be in place when the unit is operat-

ing. See table 1 for recommended lter sizes.

NOTE - Use replacement lters that are similar in size
and efciency ratings to those originally provided by the
installing contractor. Use of replacement lters with higher
ltration ratings may restrict air ow to the furnace. This
may result in reduced unit efciency, as well as premature

blower motor failure.

Page 4

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)

Maintenance

Side Return Bottom Return

Filter Size

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.

A licensed professional service technician (or equivalent)
should inspect the complete system each season (heat­ing and cooling). The following maintenance procedures
should only be conducted by a licensed professional ser­vice technician (or equivalent). Do not attempt to service

the unit in any way.

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.

CAUTION

To ensure proper operation, a licensed professional
service technician (or equivalent) should check the

burner ame and conduct a combustion analysis

annually.

Annually (before heating season) inspect furnace venting
system, vent cap, heat exchanger and burners for corro­sion, deterioration, or deposits of debris. Remove any ob­structions.

Inspect the furnace venting system to make sure it is in
place, physically sound and without holes, corrosion, or
blockage. The vent connector must be correctly posi­tioned and sloped upward. The vent connector must be
physically sound, without holes or excessive corrosion.

Inspect the furnace return air duct connection. The duct
must be sealed to the furnace and it must terminate out­side the space containing the furnace.

Inspect the physical support of the furnace to guarantee
that it is sound. The support must not sag and must not
have cracks or gaps around the base of the furnace. There
must be a seal between the furnace base and the support.

During a seasonal check, the service technician will in-

spect the indoor blower and the burner ames along with

the venting system.

Blower

Check blower wheel for any debris and clean it, if nec­essary. The blower motor is pre-lubricated for extended
bearing life. No further lubrication is needed.

WARNING

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

Service Reminder

Call your Lennox service technician if the unit will not op­erate. Before calling, always check the following to be
sure service is required.

1 - Check that electrical disconnect switches are ON.

2 - Check room thermostat for proper setting.

3 - Replace any blown fuses or reset circuit breakers.

4 - Gas valve should be ON.

5 - Air lter should not be plugged, which will limit air

ow.

6 - Is gas turned on at meter?

7 - Is manual main shut-off valve open?

Record the model and serial number of the furnace. These
numbers are on the unit nameplate, which is located below
the burners.

Serial Number ________________________________
Model Number ________________________________

Page 5

Safety Precautions

If you discover any of the following, shut down your unit,
and contact a Lennox dealer for an inspection by a licensed
professional service technician (or equivalent).

• If you repeatedly hear any new or unfamiliar sounds
while your unit is operating, there may be a prob­lem. For example, poorly performing burners can
produce unfamiliar noises.

• If you smell any unusual odors, your unit may be

operating improperly. For example, units can give
off unfamiliar odors if components are required to
operate in abnormal conditions.

• Look for visible signs of a malfunctioning unit. Ex­amples include unusual amounts of condensate on
windows inside your house, visibly burnt compo­nents or unusual dirt or rust accumulations on the
vent pipe or in the unit.

• If you experience headache, nausea, fatigue, or
dizziness, the cause could be exposure to carbon
monoxide gas. This is often misdiagnosed as the

u because symptoms are similar. If you suffer from
u-like symptoms that are exaggerated at home,

but seem to subside while you are away from the
house, exposure to carbon monoxide could be the
cause.

Your vigilance may pay off in early detection of a problem
before either personal injury or property damage occurs.

Do not hesitate to contact a qualied service technician as

an investment in your well being.

WARNING

Do not use this furnace if any part has been underwater.

A ood-damaged furnace is extremely dangerous.
Attempts to use the furnace can result in re or

explosion. Immediately call a licensed professional
service technician (or equivalent) to inspect the furnace
and to replace all gas controls, control system parts,
and electrical parts that have been wet or to replace the
furnace, if deemed necessary.

Planned Service

Annual Furnace Maintenance

At the beginning of each heating season, and to comply
with the Lennox Limited Warranty, your system should
be checked as follows by a licensed professional service
technician (or equivalent).

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

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 shut-

off 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 - See “RATE CHECK” section in the unit Installation

Instruction to ensure that the unit is operating at the

specied ring rate.

Page 6

Repair Parts

The following repair parts are available through Lennox
dealers. When ordering parts, include the complete fur­nace model number listed on the CSA International name­plate -- Example: SL280UH060NV36A-0. All service

must be done by a licensed professional installer (or
equivalent), a service agency, or the gas supplier.

Cabinet Parts

Upper access panel
Blower access panel
Top Cap

Control Panel Parts

Transformer
SureLight® integrated control
Door interlock switch
Circuit Breaker

Blower Parts

Blower wheel
Motor
Blower housing cut-off plate

Heating Parts

Flame Sensor
Heat Exchanger Assembly
Gas Manifold
Combustion Air Inducer
Gas Valve
Main Burner

Main Burner Orice

Pressure Switch
Ignitor
Primary Limit Control
Thermal Switch

WARNING

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

Page 7