Original message
| mneal
 |  "Intertherm Furance Cycles/Trouble Starting Up"
, posted Wed 30 Jan 08:51  
I have a Intertherm RSH-MS-065 fuel oil furnace in a older 900 sq ft house I bought about 3 yrs ago. The info I can find on the web it seems like it is Mobile Home furnace but???
Occasionally when you 1st turn furnace "on" it seems like it cycles power and shuts off and on rapidly. It does this even during the initial purge cycle ,the furnace pump, pilot, and blower all cycle on-off. It seems to be affected by moving the mechanical thermostat slightly either direction, making me suspect of that. There is just two wired from control board to the thermostat (red and white). Can I replace it will digital non programmable t-stat? Since I am in FL I do not use furnace often so do not have any desire for programing.
Am I even troubleshooting in proper area to suspect the t-stat?
I am hoping it is that since it seems the rest is done with the control board, and I bet t-stat is cheaper then board. I saw thru searching here that the sense probe is sometime a culprit, but since the entire power (blower , pilot etc. ) turns on & off I think that means my trouble is on the control side. I was thinking if the sense was the culprit the fan would still run...true?
Thanks, great site BTW, in a coupe hours I have learned a great deal about my new found furnace.
Cheers
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Replies:
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| djgilbert
| "Re(1):Intertherm Furance Cycles/Trouble Start" , posted Wed 30 Jan 16:52
If you feel the thermostat is the culprit, then you can remove the 2 wires from the thermostat and wirenut them together and see if it continues to cycle rapidly. If it continue, then you can take a voltage reading at the black wire going to the cad cell relay, normally a grey box with a red reset button, if power does not drop off there while thermostat is calling for heat, you most likely have a bad cad cell relay, that sounds like what it most likely is, but make sure your power isn't dropping off to the box.
Don
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| | mneal
| "Re(2):Intertherm Furnace Cycles/Trouble Start" , posted Sat 16 Feb 09:39
quote:
If you feel the thermostat is the culprit, then you can remove the 2 wires from the thermostat and wirenut them together and see if it continues to cycle rapidly. If it continue, then you can take a v
...
I replaced the T-stat, kinda wanted to upgrade the appearance anyhow, and the furnace seemed to work OK the 1st couple times. Remember I am in Florida so it does not get used very often or for long periods of time. Anyhow this morning I turned it on to remove the night chill from house and although furnace light and ran fine I could hear the relay inside the flame control box clicking, oddly the furnace stayed lite and fan ran . Perhaps the timer portion keep it running thru the relay hiccups? Anyhow it is a White&Rogers TYPE 668-410. I "Googled" it and found a place on the web that sells it for ~150. Before I start throwing more parts at it I wanted to ask the proes they opinion. I saw there are other types of burner controls that appear to be solid state, can I upgrade my control unit?
Cheers
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