I've seen some posts on line about smart thermostats for electric baseboard heaters but they all seem to be about installing Nest with relays and some complex electrical work.

Is there a method of controlling 240V electric baseboard heating using remote programable thermostats without cobbling together a makeshift system? I am asking about an approach, not a brand recommendation.

Maybe I'm missing something but I can't find any information out there!

Any help here is appreciated. Thanks!

  • 1
    Unfortunately, product recommendation questions are off-topic, as they're often only regionally useful and they become obsolete fairly quickly. – isherwood Feb 20 '17 at 18:40
  • "Line voltage wifi thermostat" and "line voltage smart thermostat" both seem to be excellent Google searches. If you specifically want Nest branded product, you need relays and proper encloser's to make that magic work, AFAIK Nest does not yet have a line voltage model. Nest's support department has chat tho, so I'd ask them... – Tyson Feb 20 '17 at 20:02

A proper transformer-and-relay system is not cobbled together and not makeshift. It is not particularly complex, and is an excellent and safe way to control electric heaters.

Relays, readily available in several packaging types, are easily installed at/near the service panel. This gives a short and simple run of the heavy power wires: breaker to nearby relay straight to the heater. This also allows both sides of the 240V to be switched, so the heater is fully de-energized when off.

With a line voltage thermostat, heavy power cables must make a lengthy detour first to the thermostat location, and then to the heater itself. (Which hopefully is not too near the thermostat). Those thermostats leave one leg of 240V connected at all times.

Heavy cables and heavy power switching makes heat. It is better to make that heat at the relay, rather than at the thermostat where it can affect the thermostat's calibration. You may have heard line voltage thermostats being very sloppy at holding temperature... this is why. A smart thermostat does nothing to fix this fundamental flaw.

24V thermostats handle only a tiny switching current, so they do not get warm from the wiring.

Lastly, line voltage thermostats lock you into only a few products. Once you go transformer/relay, you can use any modern thermostat, e.g. the Nest.

  • Yeah -- I suspect that your typical A/C compressor contactor would be happy as a clam controlling a rather tame heater instead of a nasty ol' motor load... – ThreePhaseEel Feb 21 '17 at 23:28

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