Lennox SLP99DFV Series Manual page 69

RUN MODE (2 STAGE THEREMOSTAT)
1ST OR 2ND STAGE CALL FOR HEAT ALL
INPUTS MONITORED (LIMIT, PRESSURE,
CALL FOR HEAT / COOL, FLAME LEVEL)
CALL FOR HEAT SATISFIED
3A
2nd Stage Heat
NO
2nd Stage
Call for Heat
satisfied?
YES
Combustion Air Inducer
switched to 70% rate speed
Adjust Indoor Blower
to appropiate speed
1st Stage Heat
NO
1st Stage
Call for Heat
satisfied?
YES
Gas valve
De−Energized
Combustion Air Inducer OFF
after 20−Second Post Purge
Indoor Blower OFF
after OFF Delay
1 OR
Wait for Call − Wait for Call −
2−StageThermostat Single StageThermostat
Page 69
RUN MODE (SINGLE STAGE THERMOSTAT)
3B
ALL INPUTS MONITORED (LIMIT, PRESSURE,
CALL FOR HEAT / COOL, FLAME LEVEL)
4