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Control Sequence of Operation
Start up Sequence
Upon pow ering up, the control checks for the presence of the vapor sensor, if the
resistance is in the expected range the control w ill begin normal operation after 5 to
8 seconds.
Normal Heating Sequence
1.
The thermostat senses a need for heat.
2.
The control checks the pressure sw itch condition.
3.
If the pressure sw itch is open, the control sends pow er to the blow er motor.
4.
The blow er starts moving combustion air through the combustion system.
5.
The pressure sw itch closes.
6.
The control senses the closed pressure sw itch and starts the ignition process
by providing a spark at the pilot electrode and allow ing gas to flow to the pilot.
7.
When the pilot is lit the gas control senses the pilot flame and opens the main
gas valve.
8.
The main burner is lit.
9.
The main burner and blow er continue to operate until the thermostat is
satisfied.
10. When the thermostat is satisfied the main and pilot gas valves close.
11. The blow er operates for a short post purge period before shutting dow n.
12.
The w ater heater remains in the stand-by mode until the next call for heat.
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