Black+Decker thermostat keeps shutting Off and On by itself


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Old 03-19-23, 03:04 PM
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Black+Decker thermostat keeps shutting Off and On by itself

Hi, I have a Balck + Decker Smart Thermostat that keeps shutting Off and On by itself every few minutes (10-15min). I know is shutting off because the screen goes completely blank and does not respond when you press any of the buttons and when it turns back on, I can see the messages you typically get when something is rebooting. The funny thing is that when the thermostat turns Off, the actual furnace does NOT turn Off, it keeps running normally.

Any idea what could be causing the issue?

I'm not sure if it's related but it's worth noting that the furnace doesn't pass 69 degrees even if you set it to 72, it stops momentarily when it reaches 69 degrees.

FYI: The thermostat has the C wire connected and it doesn't have batteries.

Black + Decker Smart Hard Key Thermostat
Model Number: BDXHTSL1MN

Sorry I couldn't upload images.

Thanks
 
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Old 03-19-23, 04:10 PM
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The funny thing is that when the thermostat turns Off, the actual furnace does NOT turn Off, it keeps running normally.
Are you sure it's not just the blower that's running ?

Your problem sounds like your furnace is overheating.
There should be a sight glass in the blower door where you can look in and count the fault codes.
When a furnace overheats.... it shuts the 24v off to the R terminal to the thermostat and keeps the blowers running. When the furnace cools off and resets.... or if you turn the power off and back on.... the furnace resets and the R is re-powered.

First thing to do is to check the filter.
Reduced airflow is the #1 cause of overheating.
 
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Old 03-19-23, 06:32 PM
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Are you sure it's not just the blower that's running?
I have not checked if the actual heater turns Off, I'm just going by the sound.

I'll check if there are any codes. You're maybe right, your overheating assumption makes sense.

Quick question, during a very cold day I called a guy to check out the heater since it wasn't heating the house and he said that something was wrong up in the chimney, he said something about building too much ice and he said that he was going to wait until there is no snow to work on the issue. Do you think the overheating could be caused by the ice build-up?

Thank you very much for your help!

 
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Old 03-20-23, 12:52 PM
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Are we discussing an 80% gas furnace that has a flue connected to a chimney with 3-4" metal pipe ?
There shouldn't be any ice buildup in a masonry chimney to affect the furnace.

A high efficiency furnace with a PVC flue is a different matter.
 
 

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