I have a Honeywell TH83220ZW Z-Wave Touchscreen Thermostat. It is my second one and is exhibiting the same issue as the first. It works fine except when there is a power surge or outage. Once the power stabilizes it will not reset itself. It just blanks out. I have to do a manual reset each time. I’ve replaced the battery and that didn’t work. This is not a good situation considering it could happen when we are out of town and would not be reset until we return. Absent a definitive fix I’m done with Honeywell and open to recommendations for another brand with built-in battery backup.
Issue #1: if it is truly a surge knocking out your thermostat, you’ve got bigger problems that need addressed by an electrician. A surge will likely fry your furnace or air handler board sooner than later.
Issue #2: power outages are just hard on them for sure. The battery backup in a thermostat is there to keep all your settings in place and basically prevent the issues you’re experiencing. If you’re on your 2nd thermostat with the same issue, I’d have your wiring inspected to that furnace / air handler + thermostat. Some fault may be causing a brown out (low voltage) situation that is preventing the battery backup from doing its job and making the thermostat work on regular low voltage power until it ultimately fails.
As far as recommendations, it all depends on what you have for HVAC, such as humidifier, dehumidifier, fresh air intake, 2 stage heat or cool, heat pump, geothermal, etc. Not all thermostats can handle everything.
Do you have a “C” wire? This is what should be powering the thermostat, and not just the battery.
Since you’ve tried battery replacement, I’m assuming that you have a C-Wire which is causing the issue when there is an power outage. Try disconnecting the C-Wire and see if works. If not then the thermostat is defective and would explain the issue.
There are lots of Z-Wave thermostats to choose from depending on what feature you’re looking for. For example the GoControl has additional features such as limiting the max and min temperatures. Where as the CT-101 is a Z-Wave Plus, stable but basic thermostat. You can get more details about Z-Wave thermostat models and features on this topic:
Having a “C” wire connected to the thermostat is one thing. Testing it to see if it’s producing 24 volts is another. It could very well be that the thermostat this Honeywell replaced did not require a C wire, and connecting at the thermostat does not necessarily mean it is connected at his heating unit.