Smart thermostat for electrical floor heating system

Hi openHAB community!

I’ve got an electrical floor heating system with non-smart thermostats and would like to control them via openHAB (to be able to initiate heating when enough sun energy is coming from my PV inverter).

The manufacturer of the heating system is currently not offering smart thermostats. Therefore I have to find compatible devices.

My currently used (non-smart) thermostat device is a room temperature controller with
floor temperature limiter. Thus an appropriate smart device has to have an input for the floor temperature sensor (besides its own room temperature sensor).

The manufacturer of my heating system is Halmburger (

Do you have similar setups and can recommend certain devices?

Thank you very much for your advices!

If it’s any help, I’m looking at using SunTouch to replace my controller this winter and I plan to write a binding for it when I have it for testing.

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I’m using the “MCO MH7H Water / Electrical Heating Thermostat” with the Z-Wave binding.

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I am using smart thermostats from Warmup (one 4iE and a couple of Element devices). I wrote the binding and it has been running stably for me for a few years now. They were easy to swap in for previous heatmiser devices, and have a setting for the resistance of the heat probe, and can control based on air or floor temperature, and they also make an attempt to track energy usage if you set the wattage of your heat mat.

On the guess that you might be in Germany (it’s often useful to know for hardware questions) it looks like they have local representation, I’ve seen them sold under a range of brands in other countries. I’d check with them / Halmburger as to the suitability.

Thank you, @jamesmelville, @morph166955 and @uk59821 for your quick and helpful responses!

Do any of you have experience with the Z-Wave thermostat devices by Heatit (e.g. Z-TRM6)?

@jamesmelville Thank you very much, that you took the time to give me details about your device. I can see in your binding docs that the integration is done via Warmups web service API. Do you know if a direct local connection is also possible?

Unfortunately I’ve not found a way to connect locally, port scanning the device shows nothing open, I’ve not dug into how the mobile app interacts with the devices but everything I’ve seen of it’s behaviour would lead me to assume it’s via the cloud. I’ve been happy with the API’s stability.

I did not want to replace my thermostats since new ones might not cover up the then missing wallpaper/paint… In addition to that I was looking for a cheaper solution.

My current setup started as an experiment but has proven to be very stable and successful (in terms of energy saving) last winter:

I simply put some shelly devices in front of the motors of my underfloor heating and connected the original thermostats as a switch input for the shelly. This way I can choose between two modes in OH:

  1. Use whatever the thermostat tells the heating to do. I never do this since the thermostats are crap but this would allow me to use this as a fallback when e.g. my OH machine dies and I cannot find the time to replace it immediately.
  2. I override whatever the thermostat says and control the heating through a rule in OH. I get the temperature readings from some cheap switchbot meters that are spread out everywhere in the house. The heating rule is also rather simple. Since the heating system reacts rather slow there is no need for debouncing in the rule. I was planning to add this but it just worked so well that I no longer intend to do so.
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Need to replace one of my ZTRM-2 because the relay is bust.
Have you tried the Z-TRM6 for OH integration yet?

Yes I did and it works fine. I had to register the device in the Z-Wave database (with the help of the support of the manufacturer). Since my review request for this entry is not answered yet, I assume that the device is currently not included in the OH Z-Wave binding. So you have to manually include it there by following the guide here, like I did.
If you have questions or need assistance, feel free to contact me.

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Thanks. Ordered it Y’day. Not arrived yet …

Installed Z-TRM6 just now, and it shows up with no channels.
But, I think I just wait for it to tag along in a later OH4M release. Happy with local control for now.
You can refer me as a +1 waiting for it to be included.
I also waited for a review once, after correcting and adding to the documentation, but never heard back.
Let’s hope someone picks up on your review …

I just saw that my entry was approved on 11/19. So the configuration should hopefully be included in the next release of the binding.

So it should be part of the just released openHAB 4.1 Milestone :wink:

Yes, it was: 4.1.0.M4 :slight_smile: Kudos!

I’m not complaining, but here are some points which can make this device support even better.

Controlling the setpoint is still affected by this open Z-Wave binding issue though:
Use thermostat setpoint byte size and precision from capabilities report · Issue #1708 · openhab/org.openhab.binding.zwave · GitHub (since 2021)

For the Z-TRM3 the manufacturer issued a workaround firmware, but the problem is that the OH Z-Wave binding is not honouring the parameter capability negotiation. Other Smart home vendors have fixed this.
There is no such workaround firmware for the Z-TRM6 though.
Another workaround is to always provide a value behind the decimal point, eg 17.5, 18.5, 19.5
(Setting 17, 18, 19 is not possible)

With the introduction of the Z-TRM6, the power regulator mode, from the discontinued Z-TRM2, was re-introduced. (Z-TRM3 does not have a P mode). The database does not provide a channel for controlling this though:
Here are the channels available for the old Z-TRM2:

I can recall that back in the days, Chris helped me adding the then parameter 12 as a P setting channel.
On the Z-TRM6 this is now parameter 25:

I even think he did the Display Brightness and Eco Setpoint channels as well.

Could the Binary Switch set be made Switch channels as well?

Have you looked into the API for the SunTouch Connect? I haven’t found any docs on it yet.

There isnt any good api docs. Im going to have to MITM the app and capture it. Not horrible, did it for RainSoft.