Wired hardware components for smart radiators

I´m not sure you can get an electronic thermostat for radiators, which isn´t wireless. So I guess the only option is an actuator only… It can be a little noisy when it opens, which takes a coupple of minutes, (small clicks I assume). I´m not sure if there is any actuators which doesnt clicks.

I guess I’ll give them a try then. I actually have those in my office (and many other rooms) at work, so I can ask the building manager which type / specific model number they use. Here are hundreds of radiators, so I assume they chose an inexpensive one, and I never noticed any noise since moving into the new office 5 years ago when the building was finished. So I assume I could use those also at home.

Btw I just noticed Salus has made a new fast very low energy actuator. I´m not sure if they can fit on a raditor though. But since they are self-balanced, and opening takes aprox 30 seconds, it might be worth a try if anything else fails. They come on both 230volt as well as 24volt. They´re quite expencieve though :frowning:
Type/model is: THB23030 (230volt) and THB2430.

Salus would have wired room thermostat (230volt and 24volt) with option of programming as well.

Well radiators but no radio and no batteries AND no sound - that’s a problem. Everybody to have a retrofit scenario like you uses radio controlled thermostats so there’s essentially no (mainstream) vendor to offer wired thermostats.
You have two choices:
A) deploy wireless thermostats but omit batteries and instead “fiddle” connect them to 3.3 or 5VDC power lines (to match battery voltage). Noise usually ain’t a problem.
B) deploy dumb valves used in underfloor heating and daisy chain them to an actuator of your choice. There’s systems to run on 24VDC or 230VAC but few actuators to run on 24VDC so I’d suggest the latter. Note they’re silent but binary (open or closed only) and you need to do the programming in OH yourself then, and you will also need OH-connected temperature sensors for this to work.
These valves are available as NO (normally open) for your “out of power” scenario or as NC. In theory there’s also valves that can do 1…100% but I wouldn’t use those as they are way more expensive, less reliable and programming is much more complex. Don’t underestimate the effort to get that right.

I have deployed both in my home, using MAX! thermostats on radiators and dumb valve/actuators on underflooring.

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they are not dumb, they are quite smart, but indeed you cant change them remotely.
but… is it a problem?

Yes indeed I got your point what you wanna do, but there is no valves which do the job properly as such, you simply have to sacrifice something, either battery or sound or local adjust etc.
I’m not convincing you to not to do it, but more like giving you some thoughts because I was at similar pathway.

Setting manual valves to certain level so non of your rooms will be cold as hell or hot as hell and then set certain measuring points and rules and time schedules can do basically what those “smarts” do as well.

If you wanna have one room heated to 25 while other at same time to 13 and next day other way round it definitely won’t work, and you need smart ones…, but other than that regular setup can cover all variety of situations just fine

The Salus ones look quite nice. But I guess something simpler and cheaper would do… Apparently the size is standardized to M30*1.5mm, which is what I find for most suppliers.

I guess I would go with B, since A would still need some way to attach a wire for remote control. With B, I can probably decide whether I connect them directly to OH and do the temperature dependent switching logic in OH, or have, e.g., an Arduino per room that does the switching logic, and have OH talk to the Arduino to set / read target temperature, read current temperature, read valve status etc.

In my case yes, it is, because 1. two radiators are physically inaccessible for me and 2. the remaining radiators are inaccessible while I’m traveling. Exactly as I explained.

As far as I see, having 1. an input panel in each room to set the target temperature in that room only and 2. using the binary NC or NO valves that mstormi mentioned (and which I have in my office) would do the job for me - no batteries, no wireless control, no noise, both remote and local control.

What kind of valves are you talking about? The ones I have are simple mechanical thermostats. A knob one can turn from 0 to 5. No measuring points, rules, time schedules or any kind of electronics inside.

Some or all of this may be appropriate My Central Heating Solution using Thermal Actuators

Yes - I’m using mostly WiFi stuff, but these could be replaced with non-WiFi (or, add a WiFi network purely for IoT) options - like a Raspberry Pi with multi-channel relay board hooked up to the GPIO instead of my Sonoff 4ch devices, as just one example of how to remove a WiFi component.


if those are thermo valves they close itself when room temperature is high enough (setpoint) so water flows around (2 pipe system) and open itselfs when temperature is below setpoint, so water can flow in. There is indeed no electronic needed as this is based on physics.

Anyway, as you said you need smart electronic ones, that’s fine

Indeed, that sounds like the kind of setup I would choose (except for replacing wifi with wired components, but indeed, that should not be difficult). In fact, I have read your post before posting this topic, and it was one of my sources of inspiration for the “one room is one temperature zone with a sensor and some actuators” way of solving things.

Of course, that much I know about thermostatic valves. What I meant is that there are no “time schedules” (which you mentioned in your post) or anything like that. So no chance to change the setpoint from its constant value unless I physically access the device.

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that’s why am talking about complex system. valves itselfs are not so crucial.
if you like, take some info in post of mine

Which indeed can be way different from your situation and that’s fine

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Thanks for sharing your setup as well. Indeed, that is quite a different situation. In my case I have no access to or control over the central heating unit. This is a building with around 20 apartments and central heating, so the only point where I can control something is the radiator valves.

I just noticed that your link to the actuators seems dead… They look like EAZY Drive Series 1.1 to me - at least as far as I could figure out.

ah, I’ve missed this bit somehow… then yes, your approach is the only possible tho

It appears so - the actual item isn’t too critical, it’s an M30 threaded, NC (Normally Closed), 230v 2-wire Thermal Actuator.

Here’s an alternative which is what’s throughout my new house: https://www.amazon.de/gp/product/B01HBCW5ES/

No all of these you can buy are radio controlled and don’t have wire inputs. ZWave or proprietary 433 or 868MHz. With a radio gateway or Zwave stick you can remote configure and override target temp from OH.
On B you can do OH on top of Arduino but doing so is over the top. Keep it simple.

I see, so then B it is for me. Thanks for the advice! Then my next step is to figure out how I will wire it up, i.e., where to place my OH central unit and how to connect the actuators, temperature sensors and per-room input units (if I decide to have such).

The reason why I was thinking about Arduino is that I thought of having a unit consisting of

  1. Arduino
  2. suitable temperature sensor (as suggested by Confused)
  3. rotary encoder / buttons for setpoint input
  4. LCD for local setpoint / current temperature display
  5. 230V relay (or optocoupler / triac combo) switch for valve actuators
  6. ethernet shield

in every room which has radiators (there are 3 such rooms), since each of these rooms has ethernet plugs anyway, and so it seemed the easiest way how to connect to the OH central unit in a different room. Of course, for a simple setup and testing I can start with just a temperature sensor and valve actuator connected directly to OH in one room, and then decide how to extend from there.

Hi @xenos, I recommend the Tado system.

It is wireless, and it does use batteries. I have five of these Thermostatic valves in my house. They provide actual temperature and actual humidity measurement, as well as target temperature control, with time schedule, and home/away function.

They have their own very nice app, and they also integrate very nicely in OpenHAB.

I have personally worked on the OH binding to add channels for battery low alarm monitoring, and open window detection.

The batteries are two AA cells, and in my house they last about one year.

Apparently you missed the point that I am not using wireless control / wifi or batteries, and so this does not match my requirements at all.

After some research I came up with the following per-room solution that should satisfy my requirements:

  • Arduino Uno or Mega (work better with ethernet than Nano)
  • Arduino power supply
  • ethernet shield for Arduino (or use Arduino with integrated ethernet)
  • DHT11 or DHT22 temperature + humidity sensor (has better resolution)
  • solid state relay with 5V control input and capable of switching 230V~ (Omron or similar)
  • radiator actuator (one per radiator)
  • 16 * 2 character I2C LCD display to show current temperature / humidity + setpoint
  • rotary encoder or buttons to set temperature locally

All of this hardware should fit into a small case used for electric installation (except radiator actuators).


  • local temperature regulation
  • publish temperature, humidity, setpoint via MQTT
  • listen to MQTT to change setpoint remotely (possibly with timer) via OpenHAB

No I did not miss your point. Why do you think that I specifically mentioned that in my post?

With that attitude, I wonder why you post it at all :roll_eyes: Also I wouldn’t call it an “intelligent suggestion” to recommend a wireless system in a topic that is specifically about wired components, and even says so in the title, instead of posting it somewhere where it is more likely to be found by readers who do use wireless systems and might be interested in your solution (even if you don’t care).