Thermostat Issues.

I have a oil furnace and have recently replaced the older dial thermostat with a digital thermostat. The problem I am having is that at times the furnace will not turn off when the desired temp is rached, ie, the thermostat is set at 68 but the furnace will run until it is 74. I thought that maybe air from inside the walls was causing the thermostat to read a different temp so i caulked the holes but am still having the problem. Help!
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On Jan 29, 5:13�pm, snipped-for-privacy@gmail.com wrote:

is the new thermostat located in the same place as the old one?
put the thermostat oin a outside or cold wall can cause that
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My guess is that the thermostat is turning the burner off at the desired temperature, but the blower runs independently of the thermostat and will continue to blow until the hot air is gone

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Raising the house temp from the set 68 all the way to 74? Never seen a furnace capable of doing that.
I'd re-read the installation instructions and re-check the wiring, though I can't see how incorrect wiring would result in that behavior either.
Also, remove the batteries and let it sit for awhile or follow whatever total reset procedure there is in the manual. It's possible there is a heat anticpator type setting that is whacked out. Did you by chance adjust any setting when hooking it up?

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snipped-for-privacy@optonline.net wrote:

I agree that sounds reasonable. The OP could check if the burner is off when the temp is over 68.

. Sure seems like a lot.

Maybe the digital thermostat runs on Microsoft Windows.

I agree that if there is an adjustable anticipator that has not been set, that could be the problem. The anticipator is to avoid overshoot.

*at times* the furnace will not turn off? Any pattern? If it is a setback thermostat and the temperature is returning to "normal" the temperature may overshoot. 6 degrees seems excessive.
--
bud--

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There isn't a digital thermostat made where out of the box it will go to 74 when the set temp is 68 because the anticipator was NOT set. Now, there may be one where if you screw around with it and set it wrong, it will.

.
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On Jan 30, 8:00am, snipped-for-privacy@optonline.net wrote:

...
I have forced hot water and the thermostat was put on the wall right out of the box. I didn't adjust anything. Could it be a problem oh having the wires connected to the wrong ports?
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On Jan 30, 9:03am, snipped-for-privacy@gmail.com wrote:

om...
It would seem unlikely. The thermostat is clearly able to turn the heat on and off. It seems odd that wiring could account for it going to 74 when set to 68. Did you try taking the batteries out and/or following the full reset procedure in the manual as I suggested? After that, I'd call the help line # and/or take it back.
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On Jan 30, 9:16am, snipped-for-privacy@optonline.net wrote:

.com...
i will check that out and let you know
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At this stage it would be really helpful for you to accurately and adequately describe your system. First you said you had a furnace, which turns out to be a boiler, then you said you replaced the thermostat and it turns out there are at least two thermostats. Is it a hot water baseboard system? Are there any blowers involved ? Is domestic hot water produced by the same boiler and if so, by domestic coil, or indirect tank. Are there zone valves or circulators or both and how many ? Once we have the information about your system, we may be able to help diagnose problems with it.

i will check that out and let you know
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On Jan 29, 5:13 pm, snipped-for-privacy@gmail.com wrote:

see: http://toad.net/~jsmeenen/wiring.html see: http://yourhome.honeywell.com/yourhome/Applications/Wizard/Wizard.aspx
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When I replaced my thermostat, I left a screw loose on a jumper, and because of that the furnace would not turn on. Took a couple of hours to figure out why the thing was dead. It was a factory installed jumper, and so I never bothered to check the screw. I had to take the panel off of the furnace and check it there, and when I did I found that the signal from the thermostat was not making it. Yet the screw on the thermostat was hot. Moral of the story - check all screws, even on factory installed jumpers.

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snipped-for-privacy@gmail.com wrote:

I have seen new digital thermostats just plain work bad. I have one in my motorhome. It might just be one of these bad designs. BTW, before the Honeywell, at home, I bought a unit that behaved just as you describe. I called the company. They told me to set the 'differential' to a lower setting. It was already at the lowest setting. The unit was just junk. I returned it. The Honeywell I now have works very well.
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snipped-for-privacy@gmail.com wrote:

Digital thermostats don't work, won't work, and can't be made to work.
Get a manual one, preferably the kind with the little blob of Mercury.
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I've used digital thermostats for years and years. Other then the loose screw on one, they all worked great.
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Zootal wrote:

Hmmm, I don't get it. Analog or digital, their functionality is same. Why won't it work? May need to tell the 'stat it is oil burner. Look in the system option settings per manual.
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No shop stocks the mercury stuff anymore. Environmentally toxic. Gwad. I hate the electronic stuff. And I used to fix electronics for a living. I can never remember the instructions and they are not intuitive to use or to figure out how to set. All I want is an ON OFF switch with a "just about here is right" kind of set point for a thermostat switch. Same thing with the microwave oven. All I need is a mechanical dial power setting and a clockwork timer. Nothing to read and no multiple finger stabs at the membrane switch.
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Every digital one I've ever seen will do that if you just push the HOLD buttom and then set the temp.
Same thing with the microwave oven. All I need is

The least reliable timers/clocks I've seen have all been the old mechanical ones on stoves. And they were difficult to set as well. Granted, some microwaves are overly complicated, but there are plenty that have very easy to use controls.
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After reading all the replies and additional data, I am going to guess that the overshoot might be caused by residual heat in the radiators. Many digital thermostats have a setting for hot water heat. Check the manual, as others have said. If the overshoot is more on 50 degree days than say on 10 degree days, that's a clue.
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