Lennox EL297DFV Series Unit Information page 88

Heating Sequence of Operation Continued
FIRST-STAGE HEAT
CALL FOR HEAT SATISFIED
SECOND-STAGE HEAT
2 3
2ND STAGE HEAT
2ND STAGE
CALL FOR HEAT
SATISFIED?
YES
DE−ENERGIZE 2ND STAGE
GAS VALVE
INDUCER SPEED SWITCHED
TO LOW SPEED
INDOOR BLOWER SWITCHED
TO LOW HEAT SPEED
1ST STAGE HEAT
1ST STAGE
CALL FOR HEAT
SATISFIED?
YES
GAS VALVE
DE−ENERGIZED
INDUCER OFF AFTER
5 SECOND POST PURGE
INDOOR BLOWER OFF
AFTER FIELD SELECTABLE
OFF DELAY
1
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RUN MODE:
1ST OR 2ND STAGE CALL FOR HEAT.
ALL INPUTS MONITORED (LIMIT, PRESSURE,
CALL FOR HEAT/COOL, FLAME LEVEL)
NO
NO