I have finally started my home automation journey.
I installed HAOS in a thin client, got a few sensors and have been experimenting with the settings. So far so good!
I have also gotten a few iTRVs and a smart thermostat to replace my non-smart TRVs and thermostat.
I opened the installed thermostat and found 2 cables - one the live, neutral and earth and another a one-wire cable connected to port 2 on the non-smart thermostat and that goes back to the combi boiler control unit.
Only the live wire is connected to the thermostat. My understanding is that when the temperature reaches the value set on the dial, the circuit opens and control unit shuts off the boiler. Albeit maybe over simplified, is this correct?
The image below shows the back of the Moes thermostat. I understand I need to connect the neutral and live wires to ports 3 and 4 respectively to provide power to this unit.
But what about the one-wire cable? Should I connect it to port 1 or 2? Or I need to run another cable all the way to the combi boiler control unit and wreck half of the ground floor of my home and risk divorce?
Hard to say without knowing the boiler wiring and model.
This looks like these are only 2 wires, coming from boiler.
Boiler is providing voltage for the contact.
The original thermostat is mechanical does not need 220 VAC power or other kind of supply to function.
what is connected to each wire.
I would guess, it is just a guess, the two wire connected now goes to the NO contact of the new thermostat and then you need to provide power supply L+N.
I would suggest to check everything before doing anything, you may damage thermostat or boiler!!
As far as I understand you have two thermostat chained the TM4 and the mechanical one.
If i understand correctly the white wire is connected from CH3 or 4 of TM4 when switched on closes the relay.
After that the signal goes to the mechanical thermostat that if is the case closes the contact giving the consensus to boiler.
Why having that chain, I can’t say…
The only advantage I see is the TM4 has time programs, but as you are using only one channel why don’t you move and remove one of the two thermostat as these are chained and if both are not “ON” you won’t get heating.
I believe you need to investigate too many thermostat for one circuit.
Hello,
Thank you again for your reply!
The white wire is connected to TM4’s CH1. According to the Q&A in the TM4’s official documentation (4 Zone Time Clock Programmer - Heatmiser TM4-TS) it only offers time clock outputs.
I suppose I better call up the electrician who wired my house…
too many thermostat for one circuit.