I woke up this morning and my thermostat which looks like a pocket calculator was just turned along with my furnace. I pressed both buttons and it turned back on, but my house was freezing cold. When it turned back on all of the segments on the display lit up first, and after that it worked as expected.

my thermostat

When I lived in places before I always had analog thermostats and never had them flake out like this one; the time wasn’t even set when it came back of because apparently it doesn’t keep the time; maybe the power went out and caused this, but I’m ultimately I don’t have any evidence of this.

Has anyone had experience with a thermostat like this, do I just need to buy a new one?


Here is the back of it: Back of thermostat

Here is inside the wall plate where two wires come in: Inside the wallplate

Anyway, I guess it turns on and off when bumped because the batteries aren’t held in place terribly well.

Also, to your point there isn’t much connecting it to the furnace, just two wires from plugged into a MOFSET that the thermostat plugs into via pins.

  • 3
    Does your thermostat take batteries? Can you post photos of the wiring at both the thermostat and the furnace ends? Dec 12 '19 at 12:43
  • @ThreePhaseEel How would I take it off the wall? (Sorry this is the first house I’ve ever owned)
    – leeand00
    Dec 12 '19 at 13:15
  • I wouldn’t know where to look on the Furnace end.
    – leeand00
    Dec 12 '19 at 13:19
  • 3
    We won't know either until you tell us what model they are or post photos. Most such thermostats either have a front panel that pops off, sometimes with release tabs, or the entire thing simply pulls off a backing plate.
    – isherwood
    Dec 12 '19 at 15:06
  • @ThreePhaseEel As requested, there’s my thermostat.
    – leeand00
    Dec 13 '19 at 3:34

That thermostat takes 2 AAA batteries. There is a plastic plate mounted to the wall and the thermostat can be removed from the plate by pulling up at the two bottom corners. To re-install place the top of the thermostat on the plate first then push the two bottom corners in. Upper left corner is a "Set" button. Push it and you can set the current time and day of the week using the arrows on the right. Continue pushing and you can go through four different cycles for Mon-Fri and for Sat-Sun. The cycles are Wake, Leave, Return and Sleep. When you push Set you'll see the cycle flash and either the time or temp flash. Use the arrows on the right to move the time ahead or back and the temp warmer or cooler for the cycle you want to set. Whichever one is flashing is the one you will be adjusting.

Just hitting the arrows will adjust the temperature temporarily until the next cycle occurs. If you hit hold it will hold that temperature permanently.

If you find that you need a new thermostat see if there are any rebates from the utility company for buying a programmable thermostat. I received a rebate when I bought my thermostat and if I recall it almost covered the cost of the thermostat.


99% sure this will be a thermostat that needs batteries. A fairly common approach to getting "smart" features without changing from old two-wire (heat only) mechanical thermostat wiring. I've lived with several variants - the batteries and method to get to the batteries can be less than obvious, depending on the design. If new batteries don't solve it, then it probably is new thermostat time (had that happen with one of them after 20 odd years of trouble-free service...)

Generally plan on replacing them once a year rather than waiting for them to leave the house cold. As a new homeowner, if you have not had your heating system professionally serviced annually, you might schedule a service call (for the heating system maintenance, not just for getting into the thermostat) and have the service person show you how to get to the batteries, as they will probably have a good idea how to get to them without breaking the thermostat (not uncommon to have to pull it off the wall to get to the batteries, but HOW you pull it off the wall without breaking it is not always evident.)

Otherwise, figure out what brand and model thermostat you have and look up the manual on the internet.

  • I fully agree, if the batteries are bad a minor power bump can cause problems. Normally there will be a battery symbol that is empty or the letters batt on the display when they are low. Some models like my moms will work for years on a set of batteries but with all the power outages in Northern California this year they have changed them out 2x.
    – Ed Beal
    Dec 12 '19 at 15:44

Some digital thermostats present only an up and down button. They have a display with a bunch of meaningless garf, and a big 2-digit display showing temp.

However, if you open up a little door, there are many more buttons. These are for programming. It is a programmible thermostat. At programmed times, it will reset to the programmed temp. This can be overridden by the buttons, however at the next progam time, it will again set to the program temp.

The reason I think it's programmable is that it's digital. Almost all digital thermostats that look like pocket calculators are programmable. It doesn't save much money making them non-programmable.

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