Electric Baseboard thermostat control via ST

Hi all,

I have electric baseboard at home and am currently looking into remotely controlling them via ST.

I know of this thermostat:

I also know of this relay module:

If I connect those two, theoretically, my thermostat is z-wave compatible. I know this works for insteon with no problems.
My question however is the following:
For ST, how would ST detect the thermostat and how difficult would it be to send/receive messages (i.e. set temp to 68 degrees)? I think this setup is different than the regular NEST setups.

Any insights would be greatly appreciated!


I really don’t think you need a thermostat. If you have a device with a temp sensor in the room, and a device that can turn on/off your heater, you should be able to create a device type that is essentially a virtual thermostat.

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Agreed. Get the Aeon MultiSensor and then we can create a device type for you or modify the existing Virtual Therm. smartapp to get the results you want :smile:

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Interesting idea. Haven’t thought of that.

I am quite new to getting to the device level (though I am a SW developer). Could you point me to a on/off switch? The baseboard heaters have quite a few watts so I can’t use a regular on/off switch available on this page, right?


I have a multisensor (https://shop.smartthings.com/#!/products/smartsense-multi) in my bedroom already.

Would that work, too?

So what it really comes down to is making the connection from the sensor (whichever one it may be) to the heater. I guess that is the part that I am currently stuck.

You betcha! Totally forgot STs already has a app that will do this. Just go to the “green Living” section under the app section on the app and choose “Virtual Thermostat”. This will turn on and off a switch that controls the basboard heater dependent on any temp reading that STs can produce, I.E. from your STs multi.

Now you just need to wire in the MimoLite and you should be all good! :smile:

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Dang that was easy.

Thanks guys! I will check back in a few days when I hooked the relay up to the heater!

Awesome! Defniitely share your experience! The community craves this kind of stuff :smile:

There are a couple of ways to do this; both have pros and cons.

One would be to use the multisensor as is, and just associate the two with a SmartApp. The advantage to this is that you could continue to use the multisensor as is (for other things as well). The disadvantage is that you would have to go into that SmartApp’s settings to change the setpoint (or turn it off all together).

The other way would be to create a different device type, and assign it to the sensor. In this case you could create an interface for on/off and setpoint within the device, but you would dedicate your multisensor into to being a thermostat only. However, the fact that it will look like a thermostat to SmartThings means other apps could access it as a device and control it (turn on/off/adjust setpoint).

The former is already done, the latter would take a bit of work.

Just a quick question. My baseboard is 120V and the Mimolite can’t be hooked up “in-line” to it. How would I go about that?

I guess I am looking for the “on-switch” for the baseboard. Something that is z-wave compatible but can also deal with 120V/2500W.

Hmmmm… whats the wattage? We may have to find a switch that will work for this… The mimo and Linear relays won’t handle 2500W i don’t think. THe max on the LInear is 960W…

A 4ft heater consumes about 1000W (not sure why my brain just said 2500). Sometimes they are chained to 1750W (use a 4ft and a smaller 2ft heater on one breaker/line).

Whats the max on the Mimo?

It says on the spec page:

“Output Relay 1: DPDT, Max. Switching power of 120W; 10uA to 10A;”


Could I do alternatively the following:

Use one (or more) of these guys: http://www.smarthome.com/aube-rc840t-240-on-off-switching-electric-heating-relay-with-built-in-24-v-transformer.html to wire one or more baseboard heaters to one wifi/zwave thermostat. ST could take it from there, right?

It looks like there are not really many zwave relays that can power up to 2000W.

Note that you can use any Z-Wave switch or relay closure to actuate a bigger relay. If it is 120v, you just need a SPDT N.O. relay rated at the output you require. The input can be 120V or low voltage (depending on what you have available). The Mimo’s input is low voltage, so you will need another supply for it, so might as well go for low voltage on the input side of the external relay as well.

If you want to do this all with 120v, you may want to consider a LFM-20. It’s 20 Amp rating means it should handle things by itself with no external relay required. Doubtful that the 120v circuit running to the heater is more than 20 Amps (just check your breaker box to be sure).

I’d agree with Scott here :smile:

I think the LFM 20 should be ok for you as long as you can keep the wattage under the max…

Every heater is at most 20amps, just checked it.

I guess I am confused. I googled lfm 20 and it looks like it’s for ceiling lights with at most 150W? Is that right?

Dunno what you found… 20Amps @ 120V = 2400 Watts.

Not sure I follow everything that’s flying by here, but I’ve been trying to find a way to control my electric baseboard heaters in a “smart” connected way for a couple of years now. When you get this set up working, please come back and give us a detailed explanation of what you learned. Thanks!