A problem recently developed with my furnace. I increase the thermostat and I hear the furnace "click" on. I see the orange ignition light turn on and the flame begins to flow within 10 seconds or so and then the orange light fades away and the hot air flows - which I presume is normal.


The heat continues until reaching the desired temperature. However, when the house cools, the ignition light turns on, the flame starts to flow and as the ignition light fades, the flames stop and cool air blows.


If I power off the furnace, it always works correctly the first time the heat is on, but when it goes off, it never works correctly.


Rheem Criterion II gas furnace.
Model RCBA-2457GG14
Serial M2897
Forced air
Approx 12 years old

Please excuse me for the lack of technical terms.

Thanks for any help.

Check diagnostic light. If amber light "flashes" after the flame is established, the flame sensor is dirty. Flame sensor is a small metal rod located in front of the far left burner. Disconnect power, remove it with a 1/4 inch nut driver you'll probably need an extension. Clean it with fine steel wool or sandpaper, reinstall it, turn on power and watch diagnostic lights again.

Thanks. Are the diagnostic lights located inside the furnace?

Yes, on the circuit board in the blower compartment. There is a safety door switch that turns off the power when you remove the door. Often on Rheem furnaces there is a small viewing window in the door to see the lights through.

NorthernHeat - thank you very much. It was indeed the flame rod causing the problem. Cleaned it off and now everything works fine. Thanks again for the good, accurate advice.

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Originally Posted by Eric in Mahwah

A problem recently developed with my furnace. I increase the thermostat and I hear the furnace "click" on. I see the orange ignition light turn on and the flame begins to flow within 10 seconds or so and then the orange light fades away and the hot air flows - which I presume is normal.


The heat continues until reaching the desired temperature. However, when the house cools, the ignition light turns on, the flame starts to flow and as the ignition light fades, the flames stop and cool air blows.


If I power off the furnace, it always works correctly the first time the heat is on, but when it goes off, it never works correctly.


Rheem Criterion II gas furnace.
Model RCBA-2457GG14
Serial M2897
Forced air
Approx 12 years old

Please excuse me for the lack of technical terms.

Thanks for any help.

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Hi there ,

Had the same problem with my 3 year old Rheem Criterion II and found that cleaning the flame sensor did the job perfect . Yellow LED would flash 3 times on statup then flame would go out , this would happen 2 to 3 times before the flame would finally stay on and the yellow LED would remain solid till the tempature was attained . Thanks to all for your helpful advise

Best wishes
Mark