506682−01
*P506682-01*
E 2011 Lennox Industries Inc.
Dallas, Texas, USA
Litho U.S.A.
INSTALLATION
INSTRUCTIONS
LF24
100,000 to 400,000 Btuh Series
UNIT HEATERS
506682−01
5/2011
Supersedes 503,523M
Table Of Contents
LF24 Unit Dimensions 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CSA Requirements in USA 3. . . . . . . . . . . . . . . . . . . . . . . . .
CSA Requirements in Canada 3. . . . . . . . . . . . . . . . . . . . . .
Additional Requirements 3. . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Heater Installation 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion and Ventilation Air 4. . . . . . . . . . . . . . . . . . . . .
Rotation of Combustion Air Inducer 5. . . . . . . . . . . . . . . . . .
Venting 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Connections 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical LF24 Wiring Diagram 10. . . . . . . . . . . . . . . . . . . . . . .
Gas Connection 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Check 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
Unit Start−Up 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
To Turn Off Gas to Unit 13. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating Sequence of Operation 13. . . . . . . . . . . . . . . . . . . . .
Ignition Control LED 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude Adjustment 13. . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Flow 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 15. . . . . . . . . . . . . . . . . . . . . . . . . .
Limit Control Switch 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Louver Vane Adjustments 15. . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion Air Pressure Switch 15. . . . . . . . . . . . . . . . . . . . .
Service 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start−Up and Performance Checklist 16. . . . . . . . . . . . . . . . .
Template 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WHAT TO DO IF YOU SMELL GAS:
Do not store or use gasoline or other
flammable vapors and liquids in the vi-
cinity of this or any other appliance.
Installation and service must be per-
formed by a qualified installer, service
agency or the gas supplier.
S Do not try to light any appliance.
S Leave the building immediately.
S Do not touch any electrical switch; do not use
any phone in your building.
S Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s in-
structions.
S If you cannot reach your gas supplier, call the
fire department.
FIRE OR EXPLOSION HAZARD.
Failure to follow safety warnings exact-
ly could result in serious injury, death,
or property damage.
WARNING
Be sure to read and understand the
installation, operation and service in-
structions in this manual.
Improper installation, adjustment, alter-
ation, service or maintenance can cause
serious injury, death or property damage.
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