CALLFOR 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_Ito 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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