Themostat inaccurate


Old 02-17-04, 09:43 AM
tina b
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Question Themostat inaccurate

My furnace had been acting very speratic, but once the switch was checked, and I cleaned the fuel sensor I realized it works fine, if the temp. set is actually about 10 degrees higher than what I really want it to be. I have the thermostat set at 78 and it keeps the house at about 68. I removed the cover to the thermostat, and noticed a small mtal scale with an arrow indicator on it. The arrow is set at .4, and at one end of this scale is the word "lesser". Is there something wrong with the thermostat that I can adjust, or do I need to replace it, or call for a repairman to look at the furnace itself?
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Old 02-17-04, 02:24 PM
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this setting should match the amp draw of the gas valve, replacing a tstat is a DIY will save @ 100 bucks,,,,

you can do it

we can show you how
Old 02-17-04, 02:37 PM
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If you can see a bulb with mercury in it inside the thermostat, it is also critically important that it is level. That can throw the accuracy of by several degrees. Let us know what the thermostat looks like.
Old 02-18-04, 10:26 AM
tina b
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The tsat seems to be working beautifully now, with the cover off!
There is a mercury bulb, and it does appear to be level, but for whatever reason, with the cover on it's inaccurate.Go figure??But I really appreciate the replies, and helpful insight. Thanks!
Old 02-18-04, 10:49 AM
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Lots of times I have found where some one has hit it or push the cover on the tstat so it locks up the mercury bulb. Also the hole where the wires come out is this filled in. Some times a draft in the wall will cause it to run high and low and just a lot of dust on that bimetal coil can to. Then there is the time when there is a TV or like a light right on the other side of this wall. ED
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