Thermostat with wireless sensor (and no c-wire)?

fentonc

I currently have a battery-powered, 7-day programmable honeywell thermostat on one zone of a hydronic baseboard system. There are only 2 wires to the boiler (and it would be a pain to run a new wire), and the thermostat functionality is perfectly fine, it's just in the wrong room. Is there a battery-powered, 7-day programmable thermostat that supports a remote sensor? I don't need (or even want) wifi, but I want to relocate the actual sensor.

One option would be to get something like a Honeywell T9 and just put it in the basement next to my boiler, and then put the remote sensor in the bedroom where I would like it. I could also get a plug-in 24V transformer and run it to where the current thermostat is in lieu of a c-wire from the boiler, but I would love an otherwise 'dumb' battery-powered, programmable thermostat that supported a wireless sensor. Does anyone have recommendations?

Jamie Hall

Your best bet is the one you suggest with the T9. The problem with either wireless or wi-fi thermostats requiring an outside power source is the same -- it takes a surprising amount of power to operate the transmitters in them, and the differing functionality doesn't affect that.

EdTheHeaterMan

https://www.thisoldhouse.com/heating-cooling/21016794/how-to-install-a-wireless-thermostat

fentonc

Kind of pricey, but this would work fine, right?

https://www.stromquist.com/itemdetail/YTH6320R1001

It looks like the wireless version of what I currently have (and the thermostat unit uses batteries).

ratio

+1 on @fentonc's TH6320. AFAIK that's the only Honeywell Redlink thermostat that is completely wireless. All the others require a common to use the radio.

fentonc

For the sake of closure - it wound up being easy to add a c-wire, so I went with a Honeywell TH8320R1003 and redlink indoor sensor. It was simple to wire up and get working, and now I can set the thermostat to use either bedroom or the average of the two (and I didn't need to add yet-another flaky wifi 'smart' device to my network).