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heat set to 21 thermostat reading 26 and heat still on

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  • Feb 4th, 2021 8:42 am
[OP]
Newbie
Jul 28, 2019
87 posts
29 upvotes

heat set to 21 thermostat reading 26 and heat still on

Hi. I have a furnace and heat pump system in my home. I'm used to electric baseboards so I'm learning how this system works. The thermostat is set to 21 and the house is currently 26 and getting hotter. The fan is set to auto and still running. We turned off the system with the thermostat and the fan and heat are still running. According to the thermostat, the heat pump is heating the house. We had a service call last week and don't want to have to call again. Can anyone give me an idea of what to do? Thanks.
5 replies
Member
Oct 19, 2020
328 posts
189 upvotes
disgruntledmama wrote: Hi. I have a furnace and heat pump system in my home. I'm used to electric baseboards so I'm learning how this system works. The thermostat is set to 21 and the house is currently 26 and getting hotter. The fan is set to auto and still running. We turned off the system with the thermostat and the fan and heat are still running. According to the thermostat, the heat pump is heating the house. We had a service call last week and don't want to have to call again. Can anyone give me an idea of what to do? Thanks.
Does the thermostat actually display heat is running?

Which thermostat do you have?

You can remove the t-stat off the base and see if it stops heating to rule out a wiring or controls problem downstream.
If it stops, I think you're looking at a new thermostat.

Replacing it can be tricky when there's a heatpump, especially if you have a real furnace (dual fuel system) and not an air handler with aux heat strips.
[OP]
Newbie
Jul 28, 2019
87 posts
29 upvotes
Yes, the thermostat shows the heat is running. I just shut the system off and opened the door to get some cold air in to see if the temperature goes down. The thermostat is an Emerson - no more information than that.
Member
Dec 6, 2020
303 posts
275 upvotes
If you have an electronic thermostat (e.g. one with an LCD), the firmware may have crashed. Try power cycling it. If the thermostat has batteries, remove them for ten minutes then re-install them. If the thermostat does not have batteries, turn off the circuit breakers for your furnace and heat pump for ten minutes.

If this does not help, or if you have a mechanical thermostat, then you'll need a service call and possibly a new thermostat.
Member
Oct 19, 2020
328 posts
189 upvotes
The thermostat is most likely defective if it's calling for heat when the room temperature is above the setting.
Resetting it as suggested above is a good idea, however even if it works the problem will recur. Emerson and honeywell thermostats are very reliable and run for years and years without any reset unless there's a problem.

Edit: Running on dying batteries can make the electronics go wonky, so it's worth trying a fresh set.

You can remove the thermostat off the base and confirm it is the culprit - as i suggested before.

The thermostat model is usually on the back.

I would need quite a bit of information about the system to suggest the right t-stat and give step by step wiring and setup instructions.
This is something you may want to call a pro for, specifically because you have a heatpump system.

To be clear, you have a heatpump with electric backup, right? Or is it fossil fuel backup -> like an oil or propane burning furnace?
Deal Expert
User avatar
May 10, 2005
36101 posts
10198 upvotes
Ottawa
disgruntledmama wrote: Hi. I have a furnace and heat pump system in my home. I'm used to electric baseboards so I'm learning how this system works. The thermostat is set to 21 and the house is currently 26 and getting hotter. The fan is set to auto and still running. We turned off the system with the thermostat and the fan and heat are still running. According to the thermostat, the heat pump is heating the house. We had a service call last week and don't want to have to call again. Can anyone give me an idea of what to do? Thanks.
Did this just happen? After the service call? Was it working properly until the service call? What did they service?
I suspect the thermostat has crashed or the service tech did something that affects the operation. I would certainly call them back.
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