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Normal Heating Sequence (cont’d)
7. Steady State Operation: During steady state operation, the gas control monitors:
Thermostat Temperature Sensor: When the setpoint temperature is satisfied, the
gas control is shutdown, and power is removed from the relay. The gas control
LED flashes a short flash once every 4 seconds (Idle status code).
Relay Status: If the relay is altered during a call for heat, the pilot and main valves
are shutdown. The relay is powered attempting to close the safety circuit. The gas
control LED flashes 3 times with a 3 second pause.
Flame Sensor: If flame is lost, the pilot and main valves are shutdown. The relay is
powered. The gas control attempts to re-light the pilot 4 times. If unsuccessful,
power is removed from the relay, and the gas control proceeds to a 5 minute
lockout. The gas control re-attempts to light the pilot starting at Normal Heating
Sequence #2.
8. Thermostat Satisfies: Gas control LED flashes once every 4 seconds.
9. Burner Off
10.Relay De-energized (15 seconds)
Abnormal Operation
1. Flammable Vapor Sensor Fault:
A) If the resistance is greater than 70,000 ohms: The gas control immediately turns
off all outputs. The gas control waits and monitors resistance for 30 seconds. If the
resistance is greater than 65,000 ohms after 30 seconds, the gas control proceeds
to verify resistive delay for 2 minutes and flashes 7 times then 1 time with a three
second pause. This process is repeated 5 times until the control either returns to
normal operation or proceeds to flammable vapor lockout.
B) If the resistance is below 3000 ohms: The gas control immediately turns off all
outputs and proceeds to flash 8 times then 1 time with a three second pause. The
error self clears if the resistance returns to normal range for at least 15 seconds.
Sequence of Operation
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