Challenging Rheem furnace issue.

Old 11-01-21, 06:02 PM
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Challenging Rheem furnace issue.

Have a challenge for you, I have a rheem quiet series 80 rgpn-12earjr, had a power issue. Replaced the transformer, at the moment burners will ignite (spark electrode) runs for 5-10 seconds and off. Replaced flame sensor I'm getting between 3 and 4 ua on the sensor, also tested pressure switch, and limit switches all good. No flame light. Getting good voltage into the control board, 28 out of the control board. Rewired the electrical including new grounds. Also tested polarity going to the control board also all good. Ant suggestions on what to check next?
Old 11-01-21, 09:02 PM
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Welcome to the forums.

Some furnaces can be very responsive to grounds and transformer phasing.
You just replaced the transformer. Try reversing just the 24v leads.
They aren't labeled but reversing them will reverse the phase.

Be sure the burner screws are clean and tight.
Make sure all chassis screws are tight.
Check control board ground screws.

The flame rod creates a loop from the control box.... thru the flame rod.... thru the flame to ground.... and back to the control box. You can fine tune the position of the sensor rod to increase current flow. What is the status of the amber flame status LED when burner is lit ?

Rheem manual (pdf)

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