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INSTALLATION
INSTRUCTIONS
SL280UHV
507337-01
04/2017
Supersedes 05/2016
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.
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 man-
uals, 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.
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 non-
communicating applications is illustrated in diagrams,
which begin on Page 25.
© 2017 Lennox Industries Inc.
Dallas, Texas USA
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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
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
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