Hi Kate

It sounds like your thermostat is using its adaptive intelligent recovery feature, which starts heating your home early to reach the set temperature by the programmed time. In this case, it’s likely attempting to reach 73°F by 6:30 am, causing the temperature increase around 3:30 or 4:00 am. To resolve this, you can disable the adaptive intelligent recovery feature in your thermostat settings.

I’ve written an article about this here for more info on how to use that feature – https://smarthomeperfected.com/honeywell-thermostat-recovery/

Turning this feature off should prevent the thermostat from starting the heating process ahead of schedule, keeping your temperature steady during the night.

Hope this helps

Daniel

Sorry to hear that.

If you have tried changing the battery and resetting the thermostat to 70 degrees, yet the problem persists, your options are either to get professional help (as there may be a wiring issue) or to contact Honeywell support (or the shop where you purchased the thermostat) as its likely still under warranty. They can help you troubleshoot further or discuss replacement options if necessary.

Sounds like your Honeywell thermostat might be experiencing intermittent electrical contact issues, potentially caused by the corrosion you mentioned.

Although you’ve cleaned the contacts, there could be residual damage affecting the connection. Try removing the thermostat from the wall plate again and applying some contact cleaner to the connectors.

Also, make sure the thermostat is fully pressed in when remounting.

If that doesn’t work it might be time to replace the thermostat, as it’s already been in use for a decade.

The Honeywell T4 Pro thermostat is not a smart thermostat, but it does have programmable features that could be causing the temperature changes you’re experiencing. It’s possible that schedule settings have been accidentally configured, leading to unexpected temperature adjustments. To rule this out, you can try setting the thermostat to “permanent hold” mode, which locks the desired temperature and prevents any changes. As for the fan switching to “no” from “auto,” this might be due to a miswired installation. Probably best to check with the heating plumbing company that installed your thermostat or refer to the installation manual to double-check the wiring.

The three in it were starting to corrode a little but cleaned the contacts carefully and replaced the batteries. When replacing the thermostat on the base, I made sure the male connectors were aligned and carefully pressed it into place. Immediately it lit up and worked fine. After a half an hour it the display went out again. About an hour it relit. It has been working that way for about a week.

Any ideas??

I’d like this problem solved or replaced. It’s been moths of try this try that. I’m f’n freezing.