Sequence Of Operation - Bradford White PV Series Service Manual

PV Series
Power Up Sequence
1. Start Up.
Upon power up, the control runs a safe-start check with a typical start-up delay of 5
seconds.
2. Flammable Vapor.
To assure no outputs are energized if the "Flammable Vapor Sensor" (for
RG1PV40S, RG1PV50S, RG2PV40T, RG2PV50T, RG2PV 60T, RG2PV50H) or
"Simulated Resistive Device" (for RG1PV55H and RG2PV75H) is out of range, the
control will test the "Flammable Vapor Sensor" or "Simulated Resistive Device" for
proper operating range. If the "Flammable Vapor Sensor" or "Simulative Resistive
Device" is out of range, the control LED immediately flashes 7 times with 3 second
pause.
Normal Heating Sequence
1. Thermostat calls for heat.
Prior to energizing blower, gas control checks safety circuit to ensure the circuit is
open. Normal switch positions in the safety circuit are as follows:
a) Pressure switch normally open.
b) Blower temperature switch normally closed.
If the safety circuit is closed, the control waits 4 seconds, gas control LED
flashes 2 times with 3 second pause. Gas control waits 2 minutes then,
blower runs for 30 seconds. This cycle repeats until safety circuit opens.
2. Blower energizes.
3. Pressure switch proves blower/vent system operation.
If the pressure switch does not close within 30 seconds, the control LED flashes 3
times with 3 second pause. The blower runs for 30 seconds every 2 minutes trying
to get the pressure switch or blower temperature switch to close. This cycle repeats
as long as there is a call for heat.
4. Blower pre-purge period (2 seconds).
5. Trial for pilot ignition (90 seconds).
a. The gas control lights the pilot by activating spark igniter and gas flow to pilot
burner.
b. If flame is not sensed within 90 seconds, igniter and gas flow are
deactivated, blower will post purge and control LED flashes 6 times with 3
second pause.
6. Main burner ignition.
After pilot flame is sensed, gas control activates main valve for main burner ignition.
The gas control will ignore flame and pressure switch signals for 3 seconds allowing
for main burner to stabilize.

Sequence of Operation

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