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Power Up Sequence
1. Start-up: Upon power up, the gas control runs a safe start check with a typical de-
lay of 5 seconds.
2. Flammable Vapor Verification: The gas control verifies that the Flammable Vapor
Sensor is in the proper operating range prior to energizing any components. If the
sensor is within the proper range, the gas control resumes normal operation. If the
Flammable Vapor Sensor is out of range, the gas control LED immediately flashes
7 times with a 3 second pause.
Normal Heating Sequence
When the phrase “Damper Open” is used, this means that the damper blade is in the
vertical position (open). Alternatively, “Damper Closed” means that the damper blade
is in the horizontal position (closed). This must not be confused with the phrase
“Damper Circuit Open,” as this means that the damper blade is in the horizontal posi-
tion. “Damper Circuit Closed” means that the damper blade is in the vertical position,
and the water heater can proceed to an ignition trial.
1. Thermostat Calls for Heat: Prior to energizing the damper, the gas control verifies
the damper safety circuit to see if it is in the correct state. If the safety circuit is
closed, the gas control LED flashes 2 times with a 3 second pause. The gas con-
trol waits 2 minutes. Then, the damper is powered closed. This cycle repeats until
the safety circuit opens.
2. Damper Powered Open
3. Damper Safety Circuit Check: If the damper safety circuit does not close within 30
seconds, the gas control LED flashes 3 times with a 3 second pause. The damper
is powered open for a maximum of 30 seconds every 2 minutes trying to close the
damper safety circuit. This cycle repeats as long as there is a call for heat.
4. Damper Hold Period (15 seconds)
5. Trial for Pilot Ignition (90 seconds): The gas control lights the pilot by activating
the spark igniter and gas flow to the pilot burner. If flame is not sensed within 90
seconds, the spark igniter and gas flow are deactivated. The damper will remain
open, and the gas control LED flashes 6 times with a 3 second pause.
6. Main Burner Ignition: After pilot flame is sensed, the gas control activates the
main valve for main burner ignition. The gas control will ignore flame signals for 3
seconds to allow for the main burner to stabilize.
Sequence of Operation
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