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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8327
Experience:  Furnace, A/C and heat pump specialist.
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I just changed the batteries in my honeywell thermostat, and

Customer Question

I just changed the batteries in my honeywell thermostat, and found the heat setting at 40 degrees. I pressed the up arrows to 70 degrees and the numbers slid back down to 40.
My thermostat has tree buttons on the bottom and the up and down arrows on the right with aa hold button between.
What's up?
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

What is model on the thermostat?

Expert:  airheatman replied 1 year ago.

Also try pressing the HOLD button and raising to 70 and tell me if it stays are reverts back to 40.

Customer: replied 1 year ago.
It's a Honeywell, battery powered, has three buttons on the bottom, and an up and down buttons on the right with a hold button between.
I tried pressing the hold button and raising temp to 70, but the temperature did nothing. Then I tried raising the temp to 70, then pressing the hold button. That worked for a bit, then temp went back down. It will go up and down, but wont stay at 70.
Do you have another suggestion?
Expert:  airheatman replied 1 year ago.

If thermostat will not stay at set temp with hold displayed it may have taken a power spike and have to be replaced.

There is one trick I have seen work to reset these digital thermostats that works sometimes. That is to remove batteries and install them backwards for 5 seconds, Then remove and install properly,If this does not reset the little computer board in the thermostat you will need to replace the thermostat.

Note: Occasionally , this will not work and will even cause thermostat to start smoking.If so simply remove batteries.If thermostat is not working already, it is worthless anyway, so no harm done .I have seen it work about 20 per cent of the time. So if that is something you are comfortable doing would try it.Could save you having to buy another thermostat.Otherwise, just go ahead and replace it.