Recommendable wired heating control system

Hi guys,

looking for a recommendation for a central heating control system that manages the valves over wires and is well (=ready made) compatible (=integrable) with OpenHab.

I have 15 radiators - a control wire goes to each - split into 8 zones and a central heating unit (boiler).

I seek wired system = no hassle with changing batteries, no radio interference or too long distance.

I don’t want to control the valves with OpenHab directly - I seek a ready-made system that will control the heating so, for example, I won’t have to program or sort out things like temperature hysteresis within the zones. One thermostat per zone and temperatures managed separately for each of the zone.

And - of course - the system to be open for integration into OpenHab. In this way OpenHab will serve as an umbrella system managing other tasks too but the heating control system will be capable of stand-alone operation.

There is plethora of choices for the wireless systems - I like Honeywell Evo Home for instance. But I insist on going wired way.

For wired solution I found TapHome looking promising - which however is more like less-open and less-customizable OpenHab and not the single-task (well tuned) heating control system.

Happily ready to defend my choices / explain more if questions come but will end here not to make to post too long. Any recommendation for what to look into by OpenHab community? Thanks in advance for any hint.

Good morning,

Have you considered a Velbus based system.

It’ll do exactly what you’re looking for, assuming that you have

  • A 4 core power cable to each radiator actuator.
    2 for power
    2 for ‘valve open’ microswitch - for Heat call

  • 4 core data bus cable to each zone for thermostats, which would be multi function glass panels.

The latest Velbus binding from the maintainer is really good -

The important questions are, where in the world are you and is there already a Velbus distributor near you?

Good luck,


UK Velbus importer

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Good morning Stuart,

thank you very much for the reference - and no, I didn’t come across Velbus till today. Looks promising too with few buts…

I do have 4 core cable to every each radiator actuator in the house as well as data cables to each place where the zone thermostat shall be mounted. The power cables aren’t really the 230V types (2.5mm2) but are fit to handle servos in “regular” remotely powered and controlled valves.The installation is ready for Domat control system. However to my knowledge Domat is closed system and not even open to north-bound integration into OpenHab or anything else - so I’m trying to figure out alternatives - with the ultimate goal of bringing all house subsystems under one umbrella “smart” monitoring and management.

Velbus would require a little bit more setup effort than I’d prefer but upon a first view it seems manageable. It is not mono-task (=heating control) only and I haven’t yet figured out how it handles gas boiler (Vaillant) but I guess it’s only a matter of digging into the matter deeper.

The mono-task and “work out of the box” preference for the heating control comes from one ultimate requirement: I want all house subsystems to be standardized consumer solutions that work stand-alone and if the “smart umbrella system” power cable is unplugged the entire house continues to function in the old fashioned way. If anything goes wrong with the smart integration (due to my lack of competence or lack of time to toy around with it) I want very easy way to get (temporarily) rid of it - the way my wife or children will handle effortlessly.

On the positive side Velbus seems like it could take over more tasks than just central heating.

So one of the biggest obstacles may be distribution channel - and maintenance/service/support should anything go wrong. The installation is to be done in Prague, Czech Rep. - and there seems to be no local partner :frowning: Or?

Other than that Velbus seems like fit-for-the-job!

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There’s essentially no such thing on the market (well, to the best of my knowledge). It’s probably not worth producing such a thing because only very few people are willing to put wires to all radiators when retrofitting.

Very much understandable. Not so many cases of existing house retrofit with a scale big enough so that wires are installed to all radiators without much of an extra effort and yet not making the extra step of redesigning the overall heating and switching to e.g floor heating. But here I am…

On the positive note - both Velbus and taphome seem as viable option = both are wired (!) and both are open to north-bound integration (are open systems).

Both however require more integration beyond out of the box solution for the heating itself. I’m pretty ok with toying around with integration to the umbrella management. But I’d wish for the basic function = centralized heating control to be “ready for use” (plug it in and set the time schedule & temperatures).

I very much like Honeywell Evohome which has a unit controlling the boiler, internet gateway and proprietary tablet handling the settings. Integration into overlay “smart” management is possible. But it is wireless (already now having issues with Somfy IO shades on the most distant window sometimes being inaccessible) and - most important for me - actuators (valves) operating on batteries. Call me crazy but I will not become a slave of replacing batteries in so many smart devices around the house.

There are lot more wired systems controlling heating (just like the already mentioned Domat) however these guys seem to live in the past and completely ignore “smart” world of homekits, ifttts and OpenHabs of these days (somehow I still feel they will however handle the heating control better with so many years of experience) and than there are the new kids on the block - smart, easy to install, wireless and battery operated. Getting a bit too philosophical here… …so if anyone else have any other suggestion I’d be grateful - if not, than be it Velbus or Taphome or Domat (need to see).

Well you eventually can apply an underfloor heating controller system to your radiators.
It’s using essentially disaggregated thermostats, i.e. valve and a thermometer per flooring loop or per radiator in your case.
Disaggregated BTW is an advantage as measurements of a radiator-mounted device are not representing the room temperature well enough.


I don’t think there is anything out that there that is “easy to setup” and worth having in your home.

Everything I’ve look at over the years require some degree of confusing setup.

To boil your setup down to the very basics.

Put a 4 wire actuator onto each radiator.
(24Vdv or 230Vac, both 3 Watt)

Power pair
Volt free microswitch pair

Back at your cabinet, join all the microswitch pairs together in parallel and connect them to the (I think) Volt free Heat Call terminals on your boiler.

(A simple isolating relay may be required)

So that should any ONE of the microswitches closes, the boiler will be triggered.
FYI, on a safety note, the microswitches don’t close the circuit until each valve is fully open and open the circuit as soon as the valve starts the close.
Which takes about 2 minutes in each direction.

Now join all the 0v / neutral feeds to the Actuators.

Which leaves only the +V or Live feeds for each Actuator.
These need to be connected to individual relay circuits ( IE a channel of a VMB4RYLD )

Next step is to hook up the Velbus Glass Panels in each zone, onto (ideally) a bus / loop / ring data cable.
(You can use radials if you wish, it just makes it messy back in the cabinet, where all the ends need to be joined together in parallel)

  • +15v
  • 0v
  • Data High
  • Data Low

After you get all the Velbus modules powered up, it’s just a matter of using the free software to give them base addresses and name the modules / channels.

The Heater channel of the glass panels just require 1 action to be assigned between it and the respective Relay channel for the actuator for that zone.

Action 0104 - Momentary / Follow - explanation

Any configuration you add after that would be purely to suit your needs.

You could stop there and let openHAB2 define target temperature / mode changes.

Or you can keep all of the scheduling within the Velbus ecosystem, leaving openHAB2 to ‘look in’ to make changes as required.

If you want to add the ability to move the valves once a day, without triggering the boiler, you’d only need to add an interlocking relay between the microswitches and the heat call connection of the boiler, then add a 0104 momentary action between the Pump channels of EVERY glass panel and the interlock relay.
Then activate the Unjamming option in each glass panel configuration.

A detailed generic drawing can be found here.

For anything more specific to your home / project, please send me a PM.

Any advice offered publicly should be verified with a local tradesperson, to ensure you comply with local regulations.

I can supply specific drawings for a project.

This short video shows the very basics of a Velbus system, including setting up a glass panel as a HVAC thermostat

For sure.
I have radiators AND underfloor heating, both on a Vaillant gas boiler.
My radiator thermostats are wireless (so not what you want) und my underflooring is not an autonomous system as I’d like it to be, that’s mainly because there was no suitable readymade system available when I recently reworked that floor level .
So I went for the disaggregated approach (OH-controlled valves and OH-connected temperature sensors with OH rules as the “virtual” thermostat). That ain’t as failsafe as an autonomous subsystem would be but on the other hand side I need to keep my OH alive and working anyway. Too much comfort we don’t want to miss any more in case it goes down.

Anyway, my solution with the Vaillant boiler was to insert common actuators between the boiler’s heating controller and the pumps that it controlled. It’s like a light with a connected switch that you retrofit to make it smart: the existing control continues to work. But I can override it at any time.
I do so when my ‘virtual’ thermostat calls for heat. If the water temperature drops below an acceptable level, the boiler starts heating on it’s own.
For Vaillant, if you like, there’s an EBus interface from a company called Esara, and an EBus OH binding, allowing for deep integration levels if you are willing to dive into programming.
But you don’t need it. You can essentially apply my scheme with any boiler, it’s working fine AND autonomously in case OH should fail.

Interesting. I found this thread as I’m in the same position, even registered to make this reply.

I tried Evohome and they were nice, if ugly, units, but back then there was no easy integration with a wider HA system. Like you I want certain key systems, heating, the alarm and lights, to work if the HA system comes crashing down.

Today I’m using Eurotronic Spirits, which are Z-Wave. Unfortunately they use batteries. I spent some time seemingly forever replacing batteries, until I got some of the mains powered battery replacers. This is far from ideal and is temporary. My HA system takes sensor readings from them, along with others, and send on/off to a Secure/Hostmann boiler switch (Similar to what mstomi does in this thread).

I really am surprised there isn’t a wired version of Evohome and all the other wireless systems. Maybe because, despite being out for a while, this sort of thing is actually fairly new to a lot of people and the strain of replacing batteries on multiple radiators and many other devices has not impacted people as much. Yet!

I even looked at Loxone as they do have wired versions of the radiator actuators, but they cost a lot for what they are and then there is the controller to also buy and program.

I’m not actually sure why retrofitting a wired system would seem to be a headache either, after all retrofitting low voltage wired devices to (most) rooms in the house is what an alarm engineer does regularly.

Must admit I had not heard of taphome. Looks interesting, but not quite reached my territory yet (UK).
I have been looking at Velbus as well, but never quite understood how it works or what I would need to buy and do to set it up.


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Hi Sam

Welcome to our community.

I’m sure you’ll find we’re all happy and supportive people.

You’re welcome to ask anything during your research.

If it’s specifically about Velbus (rather than a continuation of this thread), either start a new thread or send me a direct message.

Best wishes,


Hi, I also look for a solution to replace the controllers for my boiler and 4 zones.

I have a Grant Vortex condensation boiler with a single channel controller and 4 zones, that are controlled by thermostats turning 4 Grundfos circulation pumps on and off depending on temperature demand. This system seems to be cobbled to together by whoever put it in and is not optimal. The boiler I’ve already replaced (it used to be a 20 year old Firebird).

I have 40 radiators and those I’ve already fitted with AVM Fritz!DECT 301 thermostats. There is no wiring at these and there is no easy way to do this either. But I’ve got those integrated in OpenHAB already.

So what I’m looking to replace is the single channel boiler controller, the control of the circulation pumps of the 4 zones and preferable also integrate the control of the immersion with that. All of that should be OpenHAB integrated, yet be able to work autonomously and not require internet or cloud access. I don’t mind, if the wiring to the 4 zone thermostats and the boiler controller have to be revised.


Hi Marlow,

Can you indicate what the wiring is between your current setup?


Is it a bus or radials?

Is it 2 core or 4 core?

Each of the 4 zone thermostat has a 3 core 1.5mm2 230V power supply and then a 3 core cable back to the circulation pump in the press. So it essentially does nothing else than turning the circulation pump on and off based on the temperature in the hallway, where it is situated.

I guess, that could be bastardised into a power feed taken from the one 3 core cable and then using the other 3 core cable going back to the press for data.

The 1ch boiler controller has 4 x 3 core 1.5mm2 cables coming into it. One which isn’t connected, one which is the power feed, I’d presume, one that goes to the boiler and one which I don’t know what it does. I have very little knowledge on these things and only started reading up on it, when we moved to our current place, because the whole system is a mess.


Sounds like what you’re looking for is a way for each Thermostat to trigger (power on) its own circulation pump AND independently trigger the boiler.

You could achieve this by just adding a interlock relay to each Thermostat, the output of these linked together so that as long as 1 relay is closed the boiler will be triggered.

I did some research today, as it’s been bugging me for a while. This place is very old (build 1815) and every efficiency I can get will save me fuel. So I went and traced all the wires.

So, there is 3 core going from each zone thermostat to the press. I have also found out, that the remaining 3 core at the boiler controller also goes to the press.

From what I can see, the way it is wired, is that the circulation pumps only come on, when the boiler controller is feeding power to the boiler (the live to the boiler also is the live to the zone thermostats). The reason, the zone thermostats don’t go off, is because they also have batteries. Neutral from the boiler controller is wired to neutral of the circulation pumps.

Neutral of the thermostats is then wired to live of the circulation pumps.

In theory, I should be able move the entire setup to the press and then be able to make it smart from there using the existing wiring.


Okay, sounds like you have a plan forming

In regards to Velbus, is it possible just to bring the 2 wire data bus around and the power units locally ?


Thank you for asking.

If you can find a way to get 3 cores between each unit / module, then yes, there’s no reason at all why you couldn’t power each part / section / group with a tiny 12 to 18 Vdc supply and switch the 230Vac supplies for pumps where needed.

The actual data bus cable between modules has to consist of :

  • Data High
  • Data low
  • 0V / Ground reference

If you have to run a new data cable, you can use tiny installation grade microphone cable (assuming we’re not talking about very long runs).

For example this 3.2mm OD cable

Or the Van Dammed equivalent.

But if you have to run a new cable, you might as well use a 4 core EIB grade, but I understand your restrictions, so if you can use what you have already in place and just mark each cable core accordingly, you will very probably get a working system easily.

FYI, the ma current requirement for each module is shown on each product’s page of the website.

Let me know if you want any more information.

Good luck,


Stuart, you might enlighten here.

Is there an option to push a temperature reading from a third party sensor via OpenHAB to Velbus ?

Lets say, the temperature readout from an AVM Fritz!DECT thermostat or DECT repeater, read that out, let OpenHAB send that info into Velbus and Velbus should then react to this accordingly.

I’ve seen that there are virtual relays. But what about virtual sensors ?


I’m not sure what you’re asking, but the Current Temperature value from a Velbus Thermostat is Read_Only.

With the logic inside the Thermostat working with it.

You can Write the various Target Temperature values to a Velbus Thermostat, but I don’t think that’s what you’re asking.

Again, not sure what you’re asking.

Virtual relays = Items that appear as Full relays as far as logic & functionality are concerned, just without a connection to the outside world.

Virtual Sensors ? What would the point / objective be?

Are you trying to leverage the logic of a full Thermostat by using current room temperature from a different device?

The first generation Thermostat modules supported some kind of outboard or comparative temperature sensor, but that feature was never used by any installer (that I’m aware of) so was not rolled over to the new glass panel units.

Sorry if that’s not the answer/s you were hoping for.