Posted: 1/23/2014 8:13:46 AM EDT
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I'm having a problem with our natural gas furnace.
We heat primarily with wood. I mention that because it is relevant to how we use our furnace. The thermostat is set at 66 degrees, so that the house will not get too cold during the night. The woodburner will only keep the house warm for so long after I stop feeding it. So, there is often call for the furnace to kick on early in the morning. Here's what is going on. The thermostat is set to keep the house at 66 degrees. The furnace starts running at 66 degrees, and after a minute or so it shuts off, at 66 degrees. It will do this over and over and over, every few minutes. If I go to the thermostat and temporarily over-ride the setting, bump it up to 68 or 69, the furnace will run for several minutes until it hits the temp I bumped it up to, so it's not an overheating or starved for air issue. I replaced the thermostat with an identical model because it was several years old, and someone had given us an identical one new in box. It should work fine, because the problem I am describing just started a month or so ago. I opened up the furnace, checked the filter, vacuumed everything I could see or reach. Looked at the limit switch, and decided not to mess with it. Checked the wires to make sure nothing was loose, looked for a flame sensor to clean, didn't find one because the furnace is old enough it doesn't have the thin metal strip I read about as a flame sensor. The fact that it will run fine when I do a manual override of the thermostat has me puzzled. If I have the thermostat set at 66, it should kick on at 65 or so and run until it hits 68 or so, right? Any ideas? My concern is, the way it is running, it will cycle off and on 20 or 30 times an hour. That is not normal. |
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I went to the last resort.
Found the manual for the thermostat and (shudder) read the troubleshooting page. It said a loose wire might cause the situation I described. So I checked the wires and one of them was a quarter turn loose. It was making good contact, but who knows. I'll see if that cures the problem. |
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No setting on the thermostat to control range of temp differential.
If this doesn't work, I guess I'll buy a new thermostat, even though this IS a new thermostat, albeit a few years old. But like I said in the first post, this model thermostat ran the furnace fine for at least six years. |
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The thermostat did not get knocked out of orientation did it. I moved into a house and the furnace was doing the same thing as yours. The house had the old style round thermostat and it was not lined up to the arrow. Arrow is supposed to point straight up. I moved it and the furnace started to work better.
Replaced it with an electronic programmable though. |
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