1. Power on the Fresh Air Fan Module. Fresh air fans run.
2. Press the rocker switch to “HEAT” on the heater unit. The circulating fan will start.
3. Thermostat closes on call for heat providing 24 VAC to Ignition Control.
4. Blower moter is energized (@ line voltage).
5. Air pressure switch closes.
6. Once the air pressure switch closed, the igniter and gas valve are energized for an ignition trial
period.
7. Burner
ignites.
8. Flame is detected through direct flame sense detection allowing the heater to continue
operation.
9. Burner continue to fire until the thermostat is satisfied.
10. Thermostat opens interrupting power to ignition control, closing the fuel valve, and stopping
burner flame.
11. The unit enters its 60 seconds post purge period.
12. If ignition is not achieved within the ignition trial period, the gas valve is shut off ; the blower
motor continues to run for a 30 second inter-purge period. Additional ignition trials follow the
specified sequence. If all (3) trials for ignition have occurred without proper ignition and/or
flame detection, the control locks out.
13. Control may be brought out of lockout by switching the rocker switch to the OFF position and
back to the HEAT.
14. If flame is lost once it has been established, the control will shut off the gas supply and enter the
inter-purge period. Control will allow a predetermined number of flame losses before lockout.
(To restart, refer to step 13).
Sequence of Operation Overview
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