I have a Lennox electric furnace (heat pump w/ aux heat I believe) that's about 10 years old. The thermostat is a basic Honeywell digitial. The problem at hand is that the furnace only shuts off it you lower the temp setting 2-3 degree's below the room temp. It eventually kicks back on though and continues running until you repeat the process again of turning lower the temp setting. Plain and simple, it just keeps running and well after the room temperature is what we've set it for. (Ex. I set it to 68. It reaches 68 and then just keeps running.) Would replacing the thermostat with a newer one fix the problem or is it something more complex than that?

Need the model numbers of both the tstat and the furnace

Pulled the thermostat off the wall. Honeywell (number on the back read T8411R 1028 and then under that 9827 E). I believe that the model number of the outside unit, which is a Lennox, is HP290241P. Is that what you were looking for?

Here's the deal. Installed a new thermostat as a test. (Honeywell RTH3100C) Set desired temp, unit turned on as it should, house warmed up to the set temp but five minutes later it was still going. Had to knock it down a few degrees just to kick it off. What now?

If you have a heat pump system, does the outdoor unit run? Try this: Set the thermostat to operate in the emergency heat mode. Does the system shut off when the setpoint is reached? If so, the heat pump is not satisfying the 1st stage demand.

I know this sounds weird, but it's doing a few odd things. If I crank it up to 70 on regular heat and it reads as though it's reached the set temp in just a short period but as mentioned before, keeps going until I manually lower the temp setting... I did the test though. It's set on them heat. Room temp is the same as set temp and has been for almost 10 minutes now but it's still running. Doesn't seem to shut off on them mode either. My thoughts are that something is getting "satisfied" as you said, or a rely isn't sending the message to shut it off. Even wondering if it's just the fan (which is on Auto) that's continuosly blowing or is that not even a possibility?

Sure, the fan running on is a possibility, but lowering the thermostat setting to shut the system off doesn't support a strong case for that scenario. Does the supply air feel warm when you experience this "run-on" condition?

Read another post and my problem sounds very similar. Unless I mannually drop the temp setting to turn off the heater/fan, it just keeps going. The problem there seemed to be a fan relay. How do you know if the heat is still going or just the fan and if it is a fan relay is that something that can be changed out by me or should I call up someone in the field to come out and fix it?

Sorry, posted that before I saw your response. Honestly, no. The air seems a bit chilly. Always been told that "electric" heat doesn't always feel as warm to the touch as "gas" so I just assumed that was normal.

Try this: set thermostat system selector to "off", wait for system to stop. Set fan selector to "on", wait for blower to run, then back to auto. Does blower stop? Repeat a few times, system action should be consistent.

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Originally Posted by KC13

Try this: set thermostat system selector to "off", wait for system to stop. Set fan selector to "on", wait for blower to run, then back to auto. Does blower stop? Repeat a few times, system action should be consistent.

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First and foremost, thanks for helping me out with this one... Did as you said. With the thermo system selector "off" I changed the fan to on and it kicked on, then to auto and it kicked off. I tried it several times like you said and it consistently turns on with on and off with auto.

That pretty well rules out a sticky fan relay. Did you ever check to see if the outdoor unit runs when the heat is turned on?

Yes, the outside unit does run when the heat is on.

Does the insulated refrigerant line feel warm when the system runs? Slide back the insulation if necessary, to feel the copper line.

Manually kicked the heater back on (had it off to save power) and went outside to check. It's not hot to the touch by any means, but not freezing over either. You can tell there's some warmth to it.

"Some warmth" suggests that the system components are functioning as they should, but perhaps the heat pump is not operating at capacity. Did you notice any excessive ice build-up on the outdoor coil?

No, there's no ice buildup anywhere on the unit outside.

I would recommend a check of the system refrigerant charge. If it is found to be low, the system has developed a leak.

Really, that could cause the thermostat to not shut off once it reaches the desired temp? We had to get it serviced a while back because it was low only last time the problem was that the house temp just wasn't able to reach the desired temp setting. The fact that it could so this time and just wasn't kicking off made me think it had to be something different.

I have same probllem with heatpump. Had hvac to lo OK and he find link and freon and left have sam problem still

Heatpump keeps running after select temp met