Thermostat burnt!

Installed a thermostat around a year ago.

Was working fine until 2 days ago.

I pulled it out and tried to push it back in and smelled a burning smell.

I pull it out and the entire back of the thermostat is in soot!

Have no idea what it is but called a HVAC guy he said to check the fuse on air handler fuse is indeed burned.

What can it be?

Afraid to put another Wyze thermostat. Don’t want the house to burn down…

Need to see pictures of the wire connections at the Wall Plate. That is most likely where the short occured.

The fuse on the board is the safety when there is a short so the thermostat wires don’t cause a fire. When there is a short, the fuse blows and the power is cut.

Replacing the fuse will restore power, but you don’t want to do that until you identify the short.

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It worked for a year and then shorted because the wires were connected wrong? Why wouldn’t it short right away?

Here’s the wires on the plate:

No. Not saying that. The Thermostat stopped working for some reason. May not have been a short or the fuse at that point. It most likely wasn’t.

We’re there any indications of the thermostat having power when it stopped working just prior to removing it from the wall?

The short seems to have happened when you reinserted the unit to the wall. Since you didn’t smell the burning until after you reinserted it, it leads me to believe that the unit had power when you pulled it from the wall and then reinserted it. That is when the short happened and blew the fuse.

From the looks of the wires and the wall plate (which both show no evidence), as well as where the soot pattern is on the back of the thermostat, I would suspect that the RC pin on the back of the thermostat was the likely origin. It may have not been making appropriate contact when it was inserted and therefore caused some arcing. Perhaps it may have been inserted crooked or not fully seated.

My inclination would be to turn off the breaker to the HVAC and replace the fuse. It should be a 3 amp regular automotive blade style available at any auto parts store (pull the fuse and take it with you, the amp # will be printed on it… Buy extras).

Replace the fuse with the breaker off and do not mount the thermostat. Turn the breaker on and monitor for any shorts without the thermostat mounted. Turn the breaker off again and check the fuse. If it is still good, mount the thermostat taking care to insert it squarely and fully seated. Then turn the breaker back on and monitor. If it powers up, keep an eye on it. If it doesn’t, turn off the breaker and check the fuse. If it is blown again, you either have a bad thermostat, or more likely a damaged mounting plate.

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Yeah, I would contact an electrician or HVAC guy. You may need new wiring or something. This is not a problem of the Wyze Thermostat, it would most likely be a concern with other Tstat’s too. Your wiring/Furnace, etc should not have this problem with proper wiring, etc. Get it checked out just to be safe.

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I just now had the same exact issue as the OP did. This is not a known problem?? Exactly to the T as his.

Did you figure out the issue? I just had the same exact thing happen. Been running for over a year or two, no power, but when I took it off and reinserted it, it fried just like yours

For what it is worth, I recently had my thermostat do something similar, but it wasn’t the thermostat’s fault. We had a power surge hit our house and it fried my Wyze Thermostat and our HVAC/furnace needed something replaced too. So, I do know that a power surge can cause this as well as happened to me this spring/summer.

I didn’t even try to get a warranty replacement, it was definitely not Wyze’s fault when I know it was a power surge that took it out. I just went to Home Depot and bought a new one. Maybe I should’ve tried to see if my insurance or home warranty would cover it, but I suspect the copay would’ve been roughly the same cost, so I just did it myself.

I’m not saying that’s what happened in the case with anyone else in this thread, I don’t know what happened for anyone else, I just know that mine was a power surge and that those can kill it too. The power surge also killed a baby monitor.

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