[RELEASE] Stelpro releases its Maestro Line-Voltage Thermostat: The SMT402

Hi there,

Stelpro released a new thermostat, the Stelpro Maestro Thermostat (SMT402) aimed to control baseboard heaters, convectors and Fan-Forced Heaters up to 4000W powered at 240V (also works up to 2000W at 120V).


This thermostat works on ZigBee protocol.

This model includes new features:

  • Indoor humidity display
  • Overheating alert detection
  • Proximity sensing

To this date, SmartThings did not yet publish Stelpro’s device handler for the SMT402, so you may get the code here:

It is provided under the Apache 2.0 licence

The SMT402 can be purchased here:

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Where can I buy this?

Hi @jfattizzi

As stated above, it may be purchased here:

I have an oil burner furnace with baseboard heat. Is this compatible?

The thermostat may control electric baseboard, but not a furnace.

Thank you for this release.
I’m New with this thing so I don’t really know the steps to do.
I add this code on " my device handler" and I published it for me.
But after that?
I tried to add a device with the zigbee id and the device network id found on my thermostat but it’s not working.
Can you help me with that?
Thank you for your time guys

Hi @Adrien,

Once the device handler is created (by pasting the device handler code from github to your SmartThings IDE), and after doing a “publish for me”, all that is left to do is to associate your thermostat to the SmartThings hub.

To do so, click on the “add device” button, the LED on the SmartThings hub will begin to flash.
Then go on your thermostat, go in menu #1 (found in the advanced settings) and select the zigbee channel that your SmartThings hub is using.

Thank you for the answer.
When you talk about the thermostat you talking about the controller (so the black one) or the others (the white). Because for the black women I’m going on setting and zigbee system I can’t change my zigbee channel. It set at 15. So I will need to change the channel on my hub. But I don’t know where to find the channel of my hub and who to change it.

in fact it works but only with the white thermostat. and when I’m doing it I can’t control them with the Stelpro Maestro application.
But for the black thermostat (the controller) it’s not working

Hi @Adrien,

I’m refering to the “white” one, the SMT402.
This is what this thread is about.

The controller, the black one, is not compatible with SmartThings, they are both zigbee network coordinators and there can be only one in a zigbee network.

So, if your are trying to put the black one, the SMC402, in the same zigbee network as your SmartThings hub, that won’t work.

Ok. Thank you for that. So it works fine.
But I will use the application of stelpro. I paid 200$ for the black one.
Thank you anyway

Just start using it. So far so good.
Do you know if at one point the energy consumption will be part of the code?

Actually when I said ‘So far so good’, today I realized that the humidity sensor is actually not accurate at all. I’ve placed 2 other humidity sensors at the same place as the Maestro, and the Masetro is off by about 10% Which is a lot! If you consider buying this thermostat do not consider it as accurate for the humidity.
For me it is actually a big problem, as I wanted to use its sensor to trigger my dehumidifier.
I will probably return my thermostat.

Hi @vincent.barge,
Please contact Stelpro’s Customer Care so that they can help you.
Thank you

In the app when i select the Thermostat i get a Can’t connect to the device. But online i see the thermostat, temperature and setpoint. Is there anithing that i need to look ?

Hi @bperreault,

SmartThings app will report this kind of error if the device is not on the network or if the SmartThings hub is offline.

On the web page, you will always see the latest temperature and setpoint.


Found out that the App “SmartThings (Samsung Connect)” is not working getting the error message but the App “SmartThings Classic” if working fine. I switch app.

Indeed, the new SmartThings mobile app is not quite ready.
Users have been instructed to continue to use the SmartThings Classic app in the meantime.

Excellent, thank you! How can I change to Celsius?

Hi @Paybax,

Do you want to change the thermostat unit format or the SmartThings unit format?
For SmartThings, you need to go into the app preferences
For the thermostat, you may either make the change in the menu #2 or in the device handler in the thermostat’s preferences

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