Bradford White URG2PV75H N Series Service Manual page 12

UPV75 Series
Abnormal Operation (cont.)
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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Sequence of Operation