Bradford-White Corp PE4503*F(BN,SX) Manual De Usuario

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Note: The Sequence of Operation section is in addition to the Defender Atmospheric 
Service Manual, p/n 238-44943-00. 

Power Up Sequence
1.

Start-up: Upon power up, the gas control runs a safe start check with a typical 

delay of 5 seconds. 

2.

Flammable Vapor Verification: The gas control verifies that the Flammable Vapor

Sensor is in the proper operating range prior to energizing any components.  If the 
sensor is within the proper range, the gas control resumes normal operation.  If the 
Flammable Vapor Sensor is out of range, the gas control LED immediately flashes 
7 times with a 3 second pause. 

Normal Heating Sequence 
1.

Thermostat Calls for Heat: Prior to energizing the relay, the gas control verifies

the safety circuit to see if it is in the correct state.  If the safety circuit is closed, the 
gas control LED flashes 2 times with a 3 second pause.  The gas control waits 2 
minutes.  Then, the control cuts power to the relay. This cycle repeats until the
safety circuit opens. 

2.

3.

Safety Circuit Check: If the safety circuit does not close within 30 seconds, the 

gas control LED flashes 3 times with a 3 second pause.  The relay is powered for a 
maximum of 30 seconds every 2 minutes trying to close the safety circuit.  This 
cycle repeats as long as there is a call for heat. 

4.

Hold Period (15 seconds)

5.

Trial for Pilot Ignition (90 seconds): The gas control lights the pilot by activating 

the spark igniter and gas flow to the pilot burner.  If flame is not sensed within 90 
seconds, the spark igniter and gas flow are deactivated.  The relay will remain 
powered, and the gas control LED flashes 6 times with a 3 second pause. 

6.

Main Burner Ignition: After pilot flame is sensed, the gas control activates the 

main valve for main burner ignition.  The gas control will ignore flame signals for 3 
seconds to allow for the main burner to stabilize. 

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