RHEEM Model # RGDG-10EAUER intermittent problem

[waskojim]

Furnace - RHEEM Model # RGDG-10EAUER

Here are the symptoms of what I'm seeing:

- Furnace comes on and runs for a while, but doesn't continue to heat to the level the thermostat is set to.  (Matter of fact, if I cycle the thermostat down to where you hear the contacts click and separate then turn it back up to where the contacts close, the furnace starts up and runs for a while, but still under temp)

- I turned off the circuit breaker at the power panel in order to remove some sensors so I could read the part numbers.  Once I put everything back together and turned on the breaker, the furnace works normally for a few days, then the above symptom returns.

I'm suspecting it's the small sensor (47-22861-0), but am no furnace expert.  Any recommendations?

[ACtechGUY]

The absolute simplest answer would be you have a dirty filter. Or maybe you have one of those "Super Duper" filters that stop everything including AIR.

If you don't have enough airflow then the furnace WILL over heat and shutdown alot and not heat the home enough.

Besides that I need more info on the heater to help.(Sorry, I have no access to rheem info)

[waskojim]

Thanks ACtechGUY. I should have mentioned that I did replace the air filter, so it has a new one in it. Problem still exists.

[ACtechGUY]

Can you maybe post some good photos of the furnace control section and of the on the door?(macro setting on the camera for schematic)

Furnaces are pretty simple beasts, but without knowing what is there , it is kinda tuff to troubleshoot from afar.

[waskojim]

Here's a view into the furnace.

[waskojim]

Here's the part I'm suspecting.  Seems to be a sensor.  Part number 47-22861-0

[waskojim]

Here's the flow diagram from inside the lower part of the furnace, if it helps

[ACtechGUY]

Here's the part I'm suspecting. Seems to be a sensor. Part number 47-22861-0

That part is not your problem. That is a manual reset rollout switch. This part is there to stop the gas to the burner if there would happen to be a big flash of flame that ROLLsOUT from the burner box. The gas would be stopped and you would have to push that red button on the top of it to reset it.

(Your furnace would be bad if this happened!!!)

My second Thought is that the thermostat may have a problem.

IF you have a mercury bulb thermostat then maybe the heat anticipator in Stat is set wrong. If digital Stat then maybe thermostat is just bad.

IF it is a bad Overtemp switch in the heater, then it would be the one above and to the left of the draft inducer fan.(2 red wires)

[waskojim]

Good tip. I did swap out the thermostat a week or so ago and got the same result. So it looks like the next step is to try the overtemp switch in the heater. I have found that if I shut off power at the breaker to the furnace for an hour or so, that the furnace works properly for a day or two, before the symptoms return. Would a complete power cycle reset the overtemp switch?

[ACtechGUY]

I suppose that if the furnace was running alot because it was cold outside , then by shutting down the heater for several hours let everything come down to ambient temperature.

Lets say that the over temp switch was weak. Each time the heater cycled on the heater gets hot and the switch trips. it then resets but is still pretty warm and then the heater comes back on , this time it may run a slightly shorter time, and so on....

It is not likely that the electronic control in the heater is responsable for what is happening.

Here is what you need to do . Look at the temp rating on that switch. (MAYBE 140 degrees). Turn off power. Remove the switch from the heater. Insert a thermometer in the hole. Run the furnace for at least 10 minutes. If the temperature you read exceeds the rating on the switch, then the switch is ok. you have an airflow problem.

If the temp stays way under the rated temp, then it is very likely the problem is in the switch.

[Guest]

if you find your temp is exceeding the rating check your evaporator coil that can slow down your air flow also. you say you changed fikter . what type is it?

[waskojim]

Filter is just one of the standard 16"x20"x1" disposable filters.

After the last power cycle (about 8 days ago) where I cleaned off the manual reset rollout switch, the furnace has been working normally again. I'll continue to monitor for another week or so and post the results here of the final fix. No parts replaced to date, except the air filter and a cycling of the power twice from the circuit breaker.