Junkers TRQ 21 T Thermostat

Tutorials & Examples Solutions
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1

I have a Junkers TRQ 21 T Thermostat in my flat and it has two disadvantages.

  • there is an old timer clock that ticks every second which is annoying if you are not used to it (like my guests) :loudspeaker:
  • you only control specific time slots to switch between day and night mode. No differentiation between work days and weekends. :disappointed:

So I developed a controller, to connect an arduino (Wemos D1 mini) to be able to control my thermostat with openhab.

You can find my documentation here:

2

Hi Christoph,

I have the same thermostat. Perfect to find such a solution. If I understand your approach right, you are using the clock input to control the thermostat. I found out that the thermostat controls the boiler temperature by modulating 0-24V if I remember right. At the end of summer I will give it a try. Thank you to share your informations. I come back to you with a feedback … or questions:-). I am no programmer so I hope I can follow your instructions.

I wish you a nice weekend!

3

Nice to hear my solution will be useful for other people as well. :slight_smile:

Unfortunately I finished this project exactly when the “summer” started.
So I have no real life experience, yet. :smile:

At first I thought I could use the 24V modulation as well.
But I read somewhere that the thermostat does a little more than just setting the boiler to ON or OFF.
So replacing just the clock seems to be the safest solution.

4

Hey Christoph,

I have not the same but a similar thermostat. TRQ 21 (I think its just an older version.)
Did you already get some real life experience?

I think i will try to adapt your solution to my thermostat in the nearer future.

5

Yes, I had no problems in the last weeks. :grinning:

6

Hi, I have also spent alot time thinking about how to control my Junkers Heating a bit more smart. I also planed to build an Arduino based controller on my own to completely replace the existing room controller (TR100 in my case). But last year I found the Tado Smart Thermostat as replacement for the TR100 which covers all my needs out of the box.

  • Perfectly compatible to almost all Junkers Heating especially the ones which can be controlled by a TRQ21 or TR100
  • Individual Heating Plan for every day
  • Automatically Switch to Away mode by GPS Location of the Smartphone
  • Manual control
  • Early Start (start heating when I come clother to my home)
  • Perfectly integrates with Homekit, Alexa, IFTT and openHAB
  • a nice smartphone APP to configure everthing and see stistics
  • Not too expensive
  • Works out of the box without the trail and error a self build themostate would bring until it works as expected.

Especially because of the presencedetection in combination with the Smartphone app I use a very simple heating timpleplan. Only day and night, all other things like work, holidays etc works automatically.

There are also Tado Radiator Thermostats but for this I use the much cheaper MAX ones controlled by homegear. OpenHAB Switches the MAX thermostates to ECO mode if the Tado Thermostat is in Away Mode.

7

Tado might be a good alternative.

But I do not think it is cheap.
When I first heard about tado, they were only renting their devices (I think), which was a no go for me.

You can implement almost all features via openHAB.
Use OwnTracks for location tracking.

But working out of the box is a great feature, of cause.

8

The heating system in my house was replaced and my Junkers gas boiler is no more.

Now I have no need for my custom controller anymore.

If somebody is interested I would send it for 10 € + shipping in Germany. (no guarantees)

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9

Hi Christoph,
i’d be interested in your controller. I have a TRQ 21 and it doesnt suit my needs either.
Although i am quite new to this, heat controlling, smart home, openhab, i think this could help. Is it still available?
Thank you!

10

Hi Christoph @christoph_wempe! I’m reviving this old thread 4 years later because I have the same thermostat in the apartment I just moved to. I want to replicate your solution, but it seems as the code for the arduino is missing from your repo on github. Do you by any chance still have it somewhere and could push it to the github repo? That would be highly appreciated! Thanks in advance.

11

I did not use custom code.
Instead I used the Tasmota Firmaware.
https://www.tasmota.info/

Here are some information on how to configure it:
https://github.com/CWempe/Thermostat-Controller#configure-arduino-sonoff-tasmota