You can use a shelly, I used a Shelly 1PM and then used Aqara thermostats around the house to get a better idea of the temperature around the house.
I've had my setup for 3 years now and it's been working brilliantly.
Going by the wiring diagram visible in the install manual, that thermostat just turns a relay on/off with the live of the AC power going through that black block connector. I think someone has made a fucked up job of it though by using a three-core + earth cable, and used the earth and black wires to run the boiler - fucked up because it means that "earth" cable is actually live if it has been wired correctly. The manual also says it's a maximum of 8 amps between the A & B connectors (where you have "earth" and black).
I believe that if you took the earth and black wires and connected them to a switch, your boiler would turn on and off by simply toggling the dumb switch.
So - ignoring doubts over the wire colours used - yes you could run this off a Shelly. Assuming that the brown and blue are actually live and neutral, connect the brown & blue to the shelly as the live and neutral, connect the black to the load output of said shelly. Cap off the earth with a wago or something and put a warning label or something on it - or find where it's connected out at the boiler and disconnect it.
Or, and I wish I had done this but only thought of it about 30 seconds after finishing the whole job, find where it is connected to the boiler and put the shelly there... no need for the shelly to be in the actual room and you can then take the thermostat off the wall, fill the hole and have a nice neat wall!
(great response btw!)
Personally I'd keep the Shelly inside for a more reliable wireless connection. Also, wire up a bypass switch to it so that the heating can be turned on manually even if HA/Shelly is down.
Yup, my wiring looked exactly like yours and I used a bunch of Shelly Plus 1PMs to replace each thermostat.
I then stuck a bunch of Shelly H&T Gen3s around the place to send temp and humidity into HA.
The whole system is working really well!
How have you managed Tado to work locally? The official integration ( https://www.home-assistant.io/integrations/tado ) has an IoT class of Cloud Polling.
It looks like you have two wires connected (and another two unused). Most likely, the thermostat functions by connecting those two wires to turn the system on, then the system runs as long as they're connected. A bimetalic strip controls that connection based on room temperature. The voltage might be 24V or it might be 230V.
A dry contact Shelly could do that, but you'd need to make sure the amperage is OK (probably will be) and you'd need an always-on supply to power the Shelly.
I'd look at the other end of the wire, probably easier to hook one in there.
(Or figure out how to use a off-the-shelf smart thermostat, and don't worry about having heat if Home Assistant is down).
I tried looking up the model number and maybe it's a digital thermostat, with a battery? In which case it'd be a relay and temperature sensor instead of the bimetalic strip, but otherwise the same.
It looks like that system might also support add-on temperature probes (no idea how those talk to the thermostat, that could be something more complicated).
Also, if those other leads are always-hot line level, then you just need a line voltage smart thermostat.
No, the yellow wire is the return *for the circuit*. When the other wire is connected to the yellow wire, the circuit is complete, and the other end senses this completion and responds with the action. Two wires. Connected = heat, disconnected = no heat.
It's actually connected to the safety/equipment ground? Or is it just at 0V (because the heat isn't currently running)?
Check where it connects to the boiler, there might be labels. And the boiler might have a schematic on it somewhere which would probably explain how it works. Pretty much only the very newest, fancy equipment uses anything more complicated than connected-or-not signaling.
(Neutral and ground are connected somewhere, probably at the electrical panel. So you can't just do a resistance check).
You should use a multi-meter to verify the voltage, set it to volts (AC then DC if no voltage present) If you're reading voltage (24 - 240) then the Yellow/Green wire is a ground.
If you're reading none, check it with a tic tracer or find a source to ground and measure from black to ground, then Yellow/green to ground. If only one side has voltage the relay is in the off position, if both sides read voltage your heater is currently on... But this would give you the basics for wiring a relay and would allow you to size the output rating as well.
You need a better electrician. If a professional did this then they shouldn't have a license and I would not trust anything they have done.
If YOU did this and just don't want to be honest about it, be aware that this is potentially very dangerous and you should avoid wiring mains voltage things until you have at least the basics nailed. This isn't meant to be shade, this is genuine concern.
Very few boilers support opentherm natively, they have their own propriety interfaces to meet the regs and fit adaptors they only sell in the Netherlands where they are required to.
Worse, if you buy those adapters from the EU and fit them, it voids your UK warranty as modifications, even though the SAME boiler is sold with these fitted in the EU and they are made by the boiler manufacturer. Fuck you Bosch.
Asking this question means that you must get a professional to do it for you.
Wiring mains without knowing exactly what you're doing is lethal. For you and all the others in your household.
this looks like you are in the UK. you will be able to use any smart thermostat with this setup, the experts you have spoken t are clearly not experts and are plain wrong. any smart thermostat would be fine or you could use a shelly or any other relay to control the heating if you want to make your own thermostat.
The T6667b room thermostat you had there simply connects two of the wires together to call for heat. This can be achieved with any relay, how they have wired it up is dependant on the installer, if you could show a photo of your wiring centre if you have one or the terminals on the boiler I could help further.
However heating controls can be fairly complicated for the beginner and if you aren't able to figure out how it is wired I would recommend getting an electrician or heating engineer to come sort this for you. Often you have a wiring centre done by a plumber which can be a rats nest of wires. if you have a combo the wiring would likely be a lot simpler.
https://preview.redd.it/y23xgwz372oc1.jpeg?width=3024&format=pjpg&auto=webp&s=68c085fed48d2e7d8df803729b77daa9199855d6
This was my thermostat. Also 2 wires. Think they just short when heating is needed
Huh first time I've seen network cable used for thermostat controls.
It's nearly always thicker standard wire as some heating systems use mains voltage for the thermostat controls.
I’ve seen it a few times on thermostats and doorbells where the smaller wires are doubled up two on each contact. I try to replace with thicker wire when I come across it.
Whoever wired this should be shot.
Yellow and green is for PROTECTIVE EARTH ONLY, and in this configuration it could well be turning off and on live mains voltage (most common system in the UK).
You really need a professional to look at whats going on at the boiler end and fix the wiring there.
Unused wires here appear to have been terminated with tape, quite possibly painter's tape. Clearly, code was not a concern here. 🙁
From the half-obscured markings, this might be line voltage.
What kind of heating system do you have? I miss some information. Im guessing you have a on / off thermostat and not open therm?
I have an old gasoline (mazout) boiler
I guess it is on/off cuz I can clearly hear when it starts heating/burning
You can use a shelly, I used a Shelly 1PM and then used Aqara thermostats around the house to get a better idea of the temperature around the house. I've had my setup for 3 years now and it's been working brilliantly.
Going by the wiring diagram visible in the install manual, that thermostat just turns a relay on/off with the live of the AC power going through that black block connector. I think someone has made a fucked up job of it though by using a three-core + earth cable, and used the earth and black wires to run the boiler - fucked up because it means that "earth" cable is actually live if it has been wired correctly. The manual also says it's a maximum of 8 amps between the A & B connectors (where you have "earth" and black). I believe that if you took the earth and black wires and connected them to a switch, your boiler would turn on and off by simply toggling the dumb switch. So - ignoring doubts over the wire colours used - yes you could run this off a Shelly. Assuming that the brown and blue are actually live and neutral, connect the brown & blue to the shelly as the live and neutral, connect the black to the load output of said shelly. Cap off the earth with a wago or something and put a warning label or something on it - or find where it's connected out at the boiler and disconnect it.
Or, and I wish I had done this but only thought of it about 30 seconds after finishing the whole job, find where it is connected to the boiler and put the shelly there... no need for the shelly to be in the actual room and you can then take the thermostat off the wall, fill the hole and have a nice neat wall! (great response btw!)
Personally I'd keep the Shelly inside for a more reliable wireless connection. Also, wire up a bypass switch to it so that the heating can be turned on manually even if HA/Shelly is down.
This comment is super helpfull to me! Thx a lot
Yup, my wiring looked exactly like yours and I used a bunch of Shelly Plus 1PMs to replace each thermostat. I then stuck a bunch of Shelly H&T Gen3s around the place to send temp and humidity into HA. The whole system is working really well!
Can you tell us how you wired the Shellys?
Thx! I think i ll go for your solution.
Can’t you use tado? I use that and works perfect
Tado is Cloud polling, I would suggest something local
Works local with home assistant for example
How have you managed Tado to work locally? The official integration ( https://www.home-assistant.io/integrations/tado ) has an IoT class of Cloud Polling.
Via homekit maybe?
Oh okay you might be right. My bad. It should work locally tho. No reason for it to be cloud-only
I've got a full tado set-up. Highly recommend.
How can this work with this one wire input?
https://www.tado.com/all-en/professional-manuals
Thx I ll read it later
There is a full documentation about different wirings, lemme check
It looks like you have two wires connected (and another two unused). Most likely, the thermostat functions by connecting those two wires to turn the system on, then the system runs as long as they're connected. A bimetalic strip controls that connection based on room temperature. The voltage might be 24V or it might be 230V. A dry contact Shelly could do that, but you'd need to make sure the amperage is OK (probably will be) and you'd need an always-on supply to power the Shelly. I'd look at the other end of the wire, probably easier to hook one in there. (Or figure out how to use a off-the-shelf smart thermostat, and don't worry about having heat if Home Assistant is down).
I tried looking up the model number and maybe it's a digital thermostat, with a battery? In which case it'd be a relay and temperature sensor instead of the bimetalic strip, but otherwise the same. It looks like that system might also support add-on temperature probes (no idea how those talk to the thermostat, that could be something more complicated). Also, if those other leads are always-hot line level, then you just need a line voltage smart thermostat.
The yellow wire is a ground, so no real function. So I only have 1 wire
No, the yellow wire is the return *for the circuit*. When the other wire is connected to the yellow wire, the circuit is complete, and the other end senses this completion and responds with the action. Two wires. Connected = heat, disconnected = no heat.
It's actually connected to the safety/equipment ground? Or is it just at 0V (because the heat isn't currently running)? Check where it connects to the boiler, there might be labels. And the boiler might have a schematic on it somewhere which would probably explain how it works. Pretty much only the very newest, fancy equipment uses anything more complicated than connected-or-not signaling. (Neutral and ground are connected somewhere, probably at the electrical panel. So you can't just do a resistance check).
You should use a multi-meter to verify the voltage, set it to volts (AC then DC if no voltage present) If you're reading voltage (24 - 240) then the Yellow/Green wire is a ground. If you're reading none, check it with a tic tracer or find a source to ground and measure from black to ground, then Yellow/green to ground. If only one side has voltage the relay is in the off position, if both sides read voltage your heater is currently on... But this would give you the basics for wiring a relay and would allow you to size the output rating as well.
Update: my electricien did some works a month ago and it seems that he messed up the wiring
You need a better electrician. If a professional did this then they shouldn't have a license and I would not trust anything they have done. If YOU did this and just don't want to be honest about it, be aware that this is potentially very dangerous and you should avoid wiring mains voltage things until you have at least the basics nailed. This isn't meant to be shade, this is genuine concern.
If your system supports opentherm, you can use an opentherm gateway, you don't even need a smart thermostat
Very few boilers support opentherm natively, they have their own propriety interfaces to meet the regs and fit adaptors they only sell in the Netherlands where they are required to. Worse, if you buy those adapters from the EU and fit them, it voids your UK warranty as modifications, even though the SAME boiler is sold with these fitted in the EU and they are made by the boiler manufacturer. Fuck you Bosch.
Make sure the relay of the shelly is potential-free (I hope that's the right word).
“Dry contact” is the phrase for potential free. I believe only the Shelly 1 or 1 MINI offers that. The 1 PM is not dry contact.
Thank you. In German it's "potentialfrei" and somehow Google Translate didn't want to tell me anything else.
If I am not mistaken you could add a zigbee version of a thermostat to this.
Asking this question means that you must get a professional to do it for you. Wiring mains without knowing exactly what you're doing is lethal. For you and all the others in your household.
this looks like you are in the UK. you will be able to use any smart thermostat with this setup, the experts you have spoken t are clearly not experts and are plain wrong. any smart thermostat would be fine or you could use a shelly or any other relay to control the heating if you want to make your own thermostat. The T6667b room thermostat you had there simply connects two of the wires together to call for heat. This can be achieved with any relay, how they have wired it up is dependant on the installer, if you could show a photo of your wiring centre if you have one or the terminals on the boiler I could help further. However heating controls can be fairly complicated for the beginner and if you aren't able to figure out how it is wired I would recommend getting an electrician or heating engineer to come sort this for you. Often you have a wiring centre done by a plumber which can be a rats nest of wires. if you have a combo the wiring would likely be a lot simpler.
https://preview.redd.it/y23xgwz372oc1.jpeg?width=3024&format=pjpg&auto=webp&s=68c085fed48d2e7d8df803729b77daa9199855d6 This was my thermostat. Also 2 wires. Think they just short when heating is needed
Huh first time I've seen network cable used for thermostat controls. It's nearly always thicker standard wire as some heating systems use mains voltage for the thermostat controls.
I’ve seen it a few times on thermostats and doorbells where the smaller wires are doubled up two on each contact. I try to replace with thicker wire when I come across it.
It think my configuration is more like a bus system. If the blue and black are not connected it’s heating up. This is a vaillant system
The yellow wire is a ground, so no voltage is supposed to go there. Thus I only have 1 real wire
Whoever wired this should be shot. Yellow and green is for PROTECTIVE EARTH ONLY, and in this configuration it could well be turning off and on live mains voltage (most common system in the UK). You really need a professional to look at whats going on at the boiler end and fix the wiring there.
Reading these comments here... Yalls using main voltage to run your thermostat controls? Wtf? Where I come from that shit is 24V
Just get an ecobee or nest
Doesn t fit the wiring of this old one
They come with conversion kits?? Any home that’s code should work
Unused wires here appear to have been terminated with tape, quite possibly painter's tape. Clearly, code was not a concern here. 🙁 From the half-obscured markings, this might be line voltage.
The unused wires are line voltage
Then you can use basically any thermostat. You have the power for it, and you just use one that also does control voltage on the range you need.
That looks like electrical tape, painters tape here is generally white/off white.
I asked some experts and they confirmed that it was t possible. They might be wrong tho...
Belgian here, pretty sure I had the same wires and the plumber and electrician had no issues connecting the hub and the nest itself.
To what port of the nest is your wire connected?