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

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
    Jamie Hall Member Posts: 23,276
    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.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,832
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • fentonc
    fentonc Member Posts: 236
    Kind of pricey, but this would work fine, right?


    It looks like the wireless version of what I currently have (and the thermostat unit uses batteries).
  • ratio
    ratio Member Posts: 3,625
    +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
    fentonc Member Posts: 236
    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).