Bradford White URG2PV75H N Series Service Manual page 11

UPV75 Series
Abnormal Operation (cont.)
times, then 3 times twice with 3 second pause. The status self clears if the
fault clears for at least 15 seconds.
c. Water temperature in excess of ECO (energy cut out) limit -The gas
control immediately turns off pilot & main valves and proceeds to flash 4
times with 3 second pause. Blower continues to run until gas control is reset.
To reset control, rotate knob of temperature control to the minimum setting
for at least 6 seconds before returning to desired temperature setting.
3. Pressure Switch/Blower Temperature Fault:
a. Pressure switch closed at start of call for heat-the gas control waits 4
seconds then, proceeds to flash 2 times with 3 second pause. The control
waits 2 minutes and then turns on blower for 30 seconds. The blower turns
off after 30 seconds and the control waits for pressure switch to open. Any
time the pressure switch opens, the blower turns on (or stays on) and the
control proceeds to wait for pressure switch to close.
b. Pressure switch or blower temperature switch failed to close-the gas
control runs the blower for 30 seconds waiting for the pressure switch and/or
blower temperature switch to close. If either switch does not close in 30
seconds, the blower turns off and the control flashes 3 times with 3 second
pause. The gas control waits 2 minutes before turning on the blower for
another 30 seconds to see the circuit close. This cycle repeats as long as
there is a call for heat or until the circuit closes.
c. Pressure switch or blower temperature switch opens during burner
operation-the gas control turns off the pilot and main valve, runs blower for
15 seconds (inter-purge) waiting for pressure switch and/or blower
temperature switch to close. If either switch fails to close, the control
proceeds as described in 3b above, if the circuit closes again by the end of
the inter-purge, the recycle counter is incremented, 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, 2 times with 3 second pause. The gas control waits 5 minutes before
repeating ignition sequence.
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.
Sequence of Operation
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