
S9240F1004 MODULATING HOT SURFACE IGNITION INTEGRATED FURNACE CONTROL
21
69-2088—01
Fig. 11. S9240F IFC sequence Call for Heat Satisfied (Run Mode) cycle.
1st Stage Heat
2nd Stage Heat
RUN MODE (2-STAGE THERMOSTAT):
1ST OR 2ND STAGE CALL FOR HEAT.
ALL INPUTS MONITORED (LIMIT, PRESSURE,
CALL FOR HEAT/COOL, FLAME LEVEL).
3. Call for Heat Satisfied
2nd Stage
Call for Heat
satisfied?
NO
Inducer speed switched
to Mid speed
Adjust Circulator to
appropriate speed
1st Stage
Call for Heat
satisfied?
Gas valve
De-Energized
Inducer OFF
after
20 second Post Purge
Circulator OFF
after OFF Delay
YES
M28156
NO
Wait for Call -
2-Stage Thermostat
Wait for Call -
Single Stage Thermostat
1
4
3A
3B
RUN MODE (SINGLE STAGE THERMOSTAT):
ALL INPUTS MONITORED (LIMIT, PRESSURE,
CALL FOR HEAT/COOL, FLAME LEVEL).
– OR –
YES