Original message
| jing wen
 |  "Why is it necessary to ground the burner?"
, posted Sun 13 Apr 21:48  
I am a beginner in HVACR field. I have a question about the flame sensor. Why is it necessary to ground the burner when the flame sensor is working. Is it just only for the complete circuit? But I don't think so. It must have another reason, who knows? Tell me, please!!! My email address: jingwenheca@yahoo.com
Do my best in this HVACR field!!!
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Replies:
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| deanmando
| "Re(1):Why is it necessary to ground the burne" , posted Mon 14 Apr 07:53
Two things. One, if your unit is spark ignition, your spark generator is making 10,000 or so volts and depending on the gap between the rod and the burner, needs a good ground to spark well.
Two, your flame signal is also dependant on a "potential to ground" scenario, then rectified to appear as a DC signal to prove flame.
Bottom line is, you would prolly get a good ground nine times out of ten without doing anything, through screws and gas lines and ductowork ect....
But, we being proffesionals should leave nothing to chance. If the burner is grounded, thats one less thing to worry about.
For the record, in all my time at this gig, i've only had one grounding issue, but it was one of the biggest headaches and repetative nuisance I ever had.
Dean Mando
"Words are wind actions speak volumes."
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| | yuri
| "Re(2):Why is it necessary to ground the burne" , posted Mon 14 Apr 22:08
The flame sensor is not really a "sensor". It is an electrified probe which has AC to it. It gets converted to DC thru the gas flame. Passes thru the pilot burner hood or main burner as DC microamps and needs to flow back to the circuit board and be recognized as DC current or the board will lock out as flame failure. If the metal is good and clean it usually works well. Every board has a ground wire or brass grommets to the chassis or both as the S86's do to complete the circuit. It is important that the pilot burner hood and or burner face be clean also as they are part of the circuit.
Yuri
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