Lennox LF25-105A

Page 1
INSTALLATION
INSTRUCTIONS
UNIT HEATERS
507930-01
3/2019
LF25-030/105 Compact Unit Dimensions.......................2
Compact Unit Parts Arrangement ...................................3
LF25-125/200 Standard Unit Dimensions ......................4
LF25-250/400 Standard Unit Dimensions ......................5
Standard Unit Parts Arrangement...................................6
Shipping..........................................................................7
Optional Accessory .........................................................7
Requirements in USA .....................................................7
Requirements in Canada ................................................7
Additional Requirements ................................................8
Unit Heater Installation ...................................................8
Combustion and Ventilation Air.......................................8
Rotation of Combustion Air Inducer - 125/150................9
Venting............................................................................9
Electrical Connections .................................................. 14
Gas Connection ...........................................................18
Leak Check ..................................................................18
Unit Start-Up ................................................................18
To Turn O󰀨 Gas to Unit ................................................19
Heating Sequence of Operations ................................19
Ignition Control LED ....................................................20
High Altitude Adjustments ............................................20
Gas Flow .....................................................................20
Gas Pressure Adjustments .......................................... 20
Limit Control Switch ......................................................21
Louver Vane Adjustment ..............................................21
Combustion Air Pressure Switch .................................21
Flame Rollout Switch ...................................................21
Service..........................................................................21
Start-Up and Performance Checklist ........................... 22
LF25
30,000 to 400,000 Btuh Series
Table Of Contents
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
WHAT TO DO IF YOU SMELL GAS:
Do not store or use gasoline or other
cinity of this or any other appliance.
formed by a qualified installer, service
agency or the gas supplier.
Do not try to light any appliance.
Leave the building immediately.
Do not touch any electrical switch; do not use
any phone in your building.
Immediately call your gas supplier from a
neighbor's
structions.
If you cannot reach your gas supplier, call the
fire department.
FIRE OR EXPLOSION HAZARD.
Failure to
ly could result in serious injury, death,
or property damage.
WARNING
Be sure to read and understand the
structions in this manual.
ation, service or maintenance can cause
serious injury, death or property damage.
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 installer (or equivalent), service
agency or the gas supplier.
CAUTION
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.

Lennox LF25-105A Specifications

General

Configuration	Upflow/Horizontal
Input BTU	105, 000
AFUE	80%
Heating Capacity	84, 000 BTU
Efficiency	80%
Fuel Type	Natural Gas
Input Voltage	115V

Summary

INSTALLATION INSTRUCTIONS

WARNING (General Safety)

General safety warnings regarding installation, adjustment, and service.

FIRE OR EXPLOSION HAZARD

Critical safety warning about fire or explosion hazards from incorrect operation.

WHAT TO DO IF YOU SMELL GAS

Step-by-step instructions on immediate actions to take if gas is detected.

LF25-030 105 DIMENSIONS

LF25 COMPACT UNIT HEATER PARTS ARRANGEMENT

A3 CONTROL, BURNER

LF25-125 200 DIMENSIONS

LF25-250 400 DIMENSIONS

LF25 STANDARD UNIT HEATER PARTS ARRANGEMENT

T1 TRANSFORMER

GV1 GAS VALVE

B6 COMBUSTION AIR INDUCER

Installation Requirements

USA Installation Requirements

Details requirements for installation in the USA, including codes and clearances.

Canada Installation Requirements

Details requirements for installation in Canada, including codes and clearances.

GarageWarehouse Installation (USACanada)

Combustion Air Warnings

Insufficient Combustion Air Hazards

Warning about health risks and equipment damage from insufficient combustion air.

Substances Affecting Heat Exchanger

Venting Requirements

General Recommendations

General guidelines and requirements for venting unit heaters according to codes.

030-150 Units Venting

175-400 Units Venting

Venting

Single-Wall Vent Pipe Sealing

Vertical Venting Clearances

Vertical Vents - Metal Pipe

Requirements for vertical venting using metal vent pipe in commercial and residential settings.

Horizontal Venting Guidelines

Termination Location Requirements

Masonry Chimney Venting

Single Appliance Venting Prohibition

Prohibition of single appliance venting into tile-lined masonry chimneys without proper liners.

Masonry Chimney Requirements

Electrical Connections

Direct Spark Ignition System

Wiring and Grounding

Instructions for wiring, grounding, and using appropriate gauge wire.

Wiring Diagrams

High Voltage Power Connections

Low Voltage Thermostat Connections

WARNING (Servicing)

Critical safety warning about disconnecting power before servicing.

Gas Connection

Pipe Sizing and Drip Leg

Guidance on pipe sizing, maintaining pressure, and installing drip legs for gas supply.

Leak Check Procedure

Instructions for performing a gas leak check using soap solution or similar methods.

CAUTION (Ignition Sources)

Warning against using open flames or sparks for leak detection.

Unit Start-Up

SAFETY BEFORE LIGHTING

Crucial safety warnings and precautions to read before attempting to light the unit.

BEFORE LIGHTING Checks

Pre-lighting checks, including smelling for gas and handling the gas valve lever.

Gas Valve Operation

Start-Up Procedure

Step-by-step instructions for starting up the appliance, including thermostat and power settings.

To Turn Off Gas to Unit

Procedure for safely turning off the gas supply to the unit.

Heating Sequence of Operation

Ignition Sequence

Detailed explanation of the unit's heating sequence, from inducer start to fan operation.

Flame Detection and Lockout

Describes the process for flame detection, lockout, and restarting the heating sequence.

Gas Flow and Pressure

Determining Gas Flow Rate

Gas Pressure Adjustment

Instructions for checking and adjusting gas line pressure and manifold pressure.

Service and Maintenance

CAUTION (Service Safety)

Critical safety caution to turn off gas and electrical power before servicing.

Annual Inspection

Burner Cleaning Procedure

Flue Passageway and Flue Box Cleaning

Troubleshooting

Failure to Operate Checklist

Safety Shut-Off Valve Test

Start-Up and Performance Checklist

Checklist Items