Flame Sensor Light Failure


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Old 12-03-12, 02:40 PM
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Flame Sensor Light Failure

I have a new (sat for a year in the box in my house so out of warranty) Rheem RGTA-10EZAJS High Efficiency Downdraft Furnace. The furnace is not sensing the flame. I have already replaced the "Flame Sensor", the "Ignitor" as well as the "Mother Board" and it is still not sensing the flame so it shuts the flame off after 3-4 seconds.
Any Suggestions? I was wondering if the possibility of a bad "Limit Switch" might have anything to do with this.
 
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Old 12-03-12, 03:31 PM
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It's hard to believe a fan limit would open that quick,put a meter across it and see if it opens , how is the gas pressure?
 
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Old 12-03-12, 03:46 PM
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What diagnostic codes are you getting?


Use a good multimeter to measure the DC current flowing to the flame sensor while the burners are lit. That is typically 5-6 uamps DC.

For the burners to shut off as you describe the flame rectification current usually needs to be 1 uamp or less.

While this is very likely a flame sensing current issue, also check to be sure that the pressure switch isn't opening and shutting off the burner.

Checking to be sure that the ignition control is well grounded is another thing that can cause this problem.
 
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Old 12-03-12, 04:37 PM
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be sure flame is contacting flame rod
 
 

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