Home HomeKit thermostats and electric heat

Discussion in 'HomeKit, HomePod, CarPlay, Home & Auto Technology' started by boston04and07, Jan 8, 2017.

  1. boston04and07 macrumors 65816


    May 13, 2008
    Hi everyone - I'm hoping someone here would be able to answer a question about HomeKit thermostats that I can't seem to find an answer to. I recently started Homekitting up my house with the addition of iDevices switches and Philips Hue bulbs and absolutely love how it's going. It's kind of addictive, adding new accessories to the setup and having them all work with my automations, haha. So naturally, trying to get my thermostats to work with HomeKit would come next. However, this is where I'm running into some questions...

    The heating system in my house is entirely electrical, with at least one baseboard heater in each room. The house was built in the early 80s (located in New England in the northern US if that affects anything) and the thermostats we currently have are a mix of very old school turn-dial ones and somewhat old school ones that display the temperature digitally and can be programmed (but we never use that feature currently because the means of programming is kind of annoying, haha). All of the heaters are fairly small baseboard units, usually no more than three or four feet across. In researching HomeKit thermostats, however, I've found conflicting answers as to whether you can even use the main brands at all with electric baseboard heat. Ecobee, for example, says to open up an existing thermostat to check the voltage or for any high voltage warnings, but the ones I have seemingly can't be opened without completely taking them apart and have no obvious high voltage warnings on them that I can find.

    So I guess my question is, has anyone here successfully used any homekit thermostats with electric heating systems? If so, how did you know that your system was compatible? I'd love to hear any thoughts any of you guys have on this as clearly, I have no idea what I'm doing...:rolleyes:
  2. boston04and07 thread starter macrumors 65816


    May 13, 2008
    Okay, so scratch most of the above - I found one random outlier thermostat in the house that allowed me to easily take off the front plate. On the inside I did find the high voltage warnings and a warning that it was a 120v thermostat, so I guess most of the name brand smart thermostats aren't compatible with my system. Bummer! I wish a high voltage smart thermostat were on the market, I'd totally scoop a bunch up.

    Anyway, in the meantime I did find this high voltage thermostat that's compatible with Z-Wave. Now I'm thinking I could possibly get some of those (as they're more affordable than the other low-voltage ones I was looking at anyway), and try to connect them via HomeBridge, or maybe that Mixtile hub that was announced at CES this week. Or just wait for someone to release a high voltage smart thermostat, but who knows when that will be...
  3. xraydoc macrumors 604


    Oct 9, 2005
    Yeah, you may be out of luck for the time being.
  4. boston04and07 thread starter macrumors 65816


    May 13, 2008
    After doing some more research on this I'm afraid you might be right. :( I hope someone comes out with a thermostat to fill this gap at some point...it might be more of a niche market, but electric heat is semi common in my area so I bet people would buy it. I know I would!
  5. Shockwave78 macrumors 65816


    Jul 10, 2010
    If you have a 120v thermostats and no smart stats are 120v compatible then the solution is simple. You need to use a step down transformer to bring it down to 24vac.

    The leg that is switched in the stat is either the hot or common. You need to follow this wire back to where it goes. If each room has separate stats then it most likely travels through the wall down to the heater. Under the heater cover there will be both the hot/common wires to enable the heat.

    What needs to happen at this location is two things to get this to work with all standard 24vac thermostats.

    1. Buy a 120VAC/24VAC step down transformer. Look at the nameplate data on the baseboard heat(should be on the inside cover somewhere) to find out what the current(amp) draw is at 120v. Then buy a relay that is rated for over this amount. If the baseboard heater is rated at 8 amps then buy a 10 amp relay. Chances are it's not going to be over 15 amps as that's the standard circuit breaker size.

    Anyway...the transformer is about $20 and the relay and socket is about $12. That's all you need to get it done. If you decide to do it and need more info on exactly what to do or buy let me know. I have an associates in HVAC, Bachelors in IT Management and do Building Automation for a living. I deal with these types of things all the time while programming for all types of hvac, industrial, security, and anything g else that can be controlled.

    I'm in the New England as well(southern nh) if anyone ever needed help.

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