CALL
FOR HEAT SATISFIED
RUN MODE (TWO-STAGE
THERMOSTAT)
FIRST OR SECOND-STAGE
CALL FOR HEAT
ALL INPUTS MONITORED
(LIMIT, PRESSURE,
CALL FOR HEAT/COOL,
FLAME LEVEL).
f
2nd Stage Heat
I._NO
L. Call for Heat_
YES
1
I
Combustion
Air Inducer
sw tched to 70% rate speed
I_0i_s_'_0oo_'owe_
I
to appropiate
speed
---/
YES
Gas valve
De-Energized
1
Combustion
Air Inducer OFF I
after 20-Second
Post Purge
I
l
after OFF Delay
Wait for Call
Wait for Call
Two-Stage
Single-Stage
Thermostat
Thermostat
_
RUN MODE (SINGLE-STAGE
THERMOSTAT)
ALL INPUTS MONITORED
(LIMIT, PRESSURE,
CALL FOR HEAT/COOL,
FLAME LEVEL).
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