Control central heater from HA


I’m pretty new to the whole home automation subject, but I figured that since I moved in a house, now was a good time to give it a go. During the black friday craze, I spent a few euros on a conbeeII stick and a few aqara sensors as well as a yi camera, installed docker on my synology NAS with containers for HA, mosquitto and deconz, and all this looks like its working fine together (I wasn’t able to get the conbee to work with zha, but it’s working pretty nice with deconz, so whatever).

Now, my house uses a central heating system which is designed to be connected to a climate control unit through a “TT” connector. Since I already have a few temp sensors connected to HA, I’d like the control unit to actually be driven by HA, and since I already have a zigbee dongle, it would ideally use that protocol.

So I guess my questions are:

  • What kind of hardware do I need ? I kind of understood I need a “Normally closed” switch or something like that. Pretty unsure, here.
  • Once that’s settled, does it exist in the zigbee market or should I look elsewhere ?

Thanks a lot for your help !


I use a Shelly 1 relay. You can interface it via MQTT or CoAP to HASS, it connects to your WiFi network.
I also use some Aqara sensors to get temperature/humidity information from the environment and make my heater/AC react consequently.

Hey, thanks for your reply. Indeed, the use of a switch looks promising, but I’m not enough of an electrical enthusiast to be certain I won’t mix things up and send mainline current into the heater “TT” connector.

Would you be so kind and confirm that if I connect the L et N connectors to mainline and the 0 and 1 connectors to the “TT” connectors of the heater, switching the relay on will only just connect the 0 and 1 together and nothing more (220V sent to the 0/1 connectors) ? And I’m not sure I got what the SW connector is for on the Shelly1 :-/

Thanks a lot for your help.

Just use the Shelly 1, and not the Shelly 1 PM as the first one has a “clean” contact and just open/closes the circuit between the two terminals so what comes to the I terminal is short-circuited to the O terminal and you don’t risk to send any high voltage to your equipment.
I did it at my place and it works fine.

Did not get your last question though.

Thanks for confirmation.
As for my last question, I was wondering what the connector labeled SW on the Shelly 1 was, but I believe I got that now: it allows to drive the relay with a wired switch in addition to the WiFi.
Thanks again for your help !

Yes, confirmed anyway.

Hi there.

Could you please elaborate on that? Do you mean that that part of the circuit is different in the 1 and 1PM models? And that difference would make the 1PM more liable to problems?

That would be rather disappointing to me, as I’d like to measure the power used…

Thanks and best regards, Luís

The 1PM routes your mains from L1 to L when the contact is closed.
The 1 routes whatever is connected to the I to whatever is connected to the O when the contact is closed, it’s just a relay.
If you want to measure the power drawn by something you need the 1PM.