Bradford White UPV75 Series Service Manual page 11

Abnormal Operation cont.-
4. Trial for Ignition Fault:
a. Pressure switch opens during trial – The gas control turns off igniter and pilot valve. The
gas control proceeds as described in 3b above. If the pressure switch closes within 30
seconds the gas control will continue with trial for ignition starting at blower pre-purge.
b. Flame not sensed – The gas control energizes the spark igniter attempting to light the pilot
and prove flame. If flame is not sensed within 90 seconds, the igniter turns off, the pilot valve
is closed and the gas control runs the blower through post purge and flashes 6 times then,
once with 3 second pause. The control waits 5 minutes before repeating the ignition
sequence.
5. Flame Sensing Fault:
a. Flame lost during run – The gas control turns off pilot and main valves, runs blower for 15
seconds (inter-purge). The gas control increments the recycle count, if the recycle count has
not reached its limit (4), another trial for ignition begins. If the recycle count has been
reached, the gas control turns off the blower and flashes 6 times then, 3 times with 3 second
pause. The gas control waits 5 minutes before repeating the ignition sequence.
b. Flame sensed out of sequence – The gas control only looks for pilot flame when the blower
is running. If flame is present when the pilot valve is not open, the gas control proceeds to
wait for flame loss and flashes 5 times with 3 second pause. This continues until flame is
lost. Once the flame signal is lost, the control flashes 6 times then, 4 times with 3 second
pause. The control waits 5 minutes before repeating the ignition sequence.
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