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Troubleshooting continued-
Control Sequence of Operation
Start up Sequence
Upon powering up, the control checks for the presence of the flammable vapors, if the
resistance is in the expected range the control will begin normal operation after 5 to 8
seconds.
Normal Heating Sequence
1. The thermostat senses a call for heat.
2. The control checks that the relay contacts are open.
3. The control sends power to the relay, which then closes the relay contacts.
4. The control starts the ignition process by providing a spark at the pilot electrode
and allowing gas to flow to the pilot.
5. When the pilot is lit, the gas control senses the pilot flame and opens the main gas
valve.
6. The main burner is lit.
7. The main burner continues to operate until the thermostat is satisfied.
8. When the thermostat is satisfied, the main and pilot gas valves close.
9. The relay contacts remain closed for a short period before opening.
The water heater remains in the stand-by mode until the next call for heat.