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Servicing should only be performed by a Qualifi ed Service Agent
OPERATION AND SERVICE
ELECTRICAL SEQUENCE
1. Switch Power on to unit.
2. Thermostat calls for heat.
3. Ignition Control Board performs diagnostic check on system components.
4. On completion of diagnostics check, the Ignition Control Board energizes the Blower
(Draft Inducer).
5. The Blower (Draft Inducer) begins drawing air through appliance, closing the Blower
Prover Switch.
6. On completion of Blower Prover Switch engagement, the Ignition Control Board begins
the ignition cycle.
7. The Ignition Control Board provides power to the Silicon Nitride Igniter.
8. The Silicon Nitride Igniter heats up for approximately 17 to 20 seconds.
9. At the end of Silicon Nitride Igniter’s warm-up, the Ignition Control Board opens the
Gas Valve.
10. From the time the Gas Valve opens, the Ignition Control Board waits 3 seconds
and then shuts off power to the Silicon Nitride Igniter.
11. From the time the Silicon Nitride Igniter’s power is shut off, the Ignition Control
Board waits 3 more seconds to monitor the Flame Sensor.
12. If the Ignition Control Board does not detect flame at the burners, it will de-energize the
Gas Valve and run the Blower for approximately 20 seconds to purge the combustion
chamber. The Ignition Control Board then restarts at Step 7 for up to 2 more trials
for ignition. After the third failed trial for ignition, the Ignition Control Board locks out
for one hour. At the end of this lock out period, the Ignition Control Board will restart
at Step 3 for three more trials. NOTE: The one hour lock out period can be reset by
cycling power to the water heater off and on again.
13. If the Ignition Control Board detects a strong flame from the Flame Sensor, it will remain
in the heating mode until the Thermostat is satisfied.
14. When the Thermostat is satisfied, the Ignition Control Board will de-energize the Gas
Valve and run the Draft Inducer for approximately 20 seconds to purge the combustion
chamber. The Ignition Control Board will then go into standby mode.