Thermostat Restarts during Heat Stage 2 Usage and Testing

One of my (3) Wyze thermostats restarts every time it engages Heat Stage 2. Has anyone else experienced thus? Heat Stage 1 and Cool Stage 1 test, and run, just fine… but Heat Stage 2 is not working. This might be coincidental - but this has been an issue in the past 24 hours… within a day of updating to the most recent firmware for the device: 1.2.4.a2.

Here is a folder with some pictures of the thermostat and furnace wiring.

I have tried resetting the unit, a handful of times now. I have called support and talked with them… submitted a case for the engineers…

In the original Honeywell wiring picture, the green wire was attached to “G” prior to the picture.

I will say - before yesterday - the thermostat acted normally… I also might have selected “O/B” during the initial setup, instead of “O.” I was originally prompted to identify the type of furnace I had, or whether or not I had a heat pump. When I set up the thermostat this time, the setup procedure did not require this information.

I did try to swap one of my functioning units for this unit, and Heat Stage 2 restarts that unit as well.

The voltage going to the thermostat (tested at the transformer in the furnace) is 27V… and should allow it to hit 24(ish [not tested at thermostat]) as it gets to the thermostat, which is probably 35ft of wire away…

I didn’t recognize any issues prior to yesterday, however we really didn’t get super cold weather in this area up until this week… so I’m beginning to wonder if Heat Stage 2 is Emergency Heat? The temperature dropped into the low 40’s at night over the past two nights.

Not sure…

Any help or knowledge would be greatly appreciated!

Stage 2 heat on a heatpump is heat strips or emergency heat. It is possible that the inrush current to the heat strip contactor coil is pulling the voltage to the thermostat low enough that it is turning off on low voltage.

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