Lennox International Inc Essential Lennox Furnace Repair Parts for Efficient Heating Solutions

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

NOTE - In these applications, two-stage heat will be initi­ ated by the integrated control if heating demand has not been satisfied after the field adjustable period (7 or 12 min­ utes).

1 - On a call for heat, thermostat first-stage contacts close sending a signal to the integrated control. The inte­ grated 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 ener­ gized at low speed.

2 - Once the control receives a signal that the low pres­ sure switch has closed, the combustion air inducer be­ gins a 15-second pre-purge in low speed.

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

3 - After the pre-purge is complete, a 20-second initial ig­ nitor warm-up period begins. The combustion air in­ ducer continues to operate at low speed.

4 - After the 20-second warm-up period has ended, the gas valve is energized on low fire (first stage) and ignition oc­ curs. At the same time, the control module sends a sig­ nal to begin an indoor blower 30-second ON-delay. When the delay ends, the indoor blower motor is ener­ gized on the low fire heating speed and the HUM con­ tacts are energized. The integrated control also initi­ ates a second-stage on delay (factory-set at 7 minutes; adjustable to 12 minutes).

5 - If the heating demand continues beyond the second- stage on delay, the integrated control energizes the combustion air inducer at high speed. The control also checks the high fire (second stage) pressure switch to make sure it is closed. The high fire (second stage) gas valve is energized and the indoor blower motor is energized for operation at the high fire heating speed.

6 - When the thermostat heating demand is satisfied, the combustion air inducer begins a 5-second low speed post-purge. The field-selected indoor blower off delay begins. The indoor blower operates at the low-fire heating speed.

7 - When the combustion air post-purge period is com­ plete, 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.

Repair Parts List

The following repair parts are available through Lennox dealers. When ordering parts, include the complete fur­ nace model number listed on the CSA nameplate -- Exam­ ple: EL296UH045XE24B-01. All service must be per­ formed by a licensed professional installer (or equivalent), service agency, or gas supplier.

Cabinet Parts

Outer access panel

Blower access panel

Top Cap

Control Panel Parts

Transformer

Integrated control board

Door interlock switch

Blower Parts

Blower wheel

Motor

Motor mounting frame

Motor capacitor

Blower housing cutoff plate

Heating Parts

Flame Sensor

Heat exchanger assembly

Gas manifold

Combustion air inducer

Gas valve

Main burner cluster

Main burner orifices

Pressure switch

Ignitor

Primary limit control

Flame rollout switches

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