Lennox SL280DFNV Series Unit Information page 49

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