Bradford White RG1PV50S6X19-264 Manual page 36

Troubleshooting continued-
Control Sequence of Operation
Start up Sequence
Upon powering up, the control checks for the presence of the vapor sensor, 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 need for heat.
2. The control checks the pressure switch condition.
3. If the pressure switch is open, the control sends power to the blower motor.
4. The blower starts moving combustion air through the combustion system.
5. The pressure switch closes.
6. The control senses the closed pressure switch and starts the ignition
process by providing a spark at the pilot electrode and allowing 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 blower continue to operate until the thermostat is
satisfied.
10. When the thermostat is satisfied the main and pilot gas valves close.
11. The blower operates for a short post purge period before shutting down.
12. The water heater remains in the stand-by mode until the next call for heat.
36