Connect Gas boiler and A/C to Sonoff NSPanel PRO

Hi, I’m new to this and I would like to receive some advice from all of you.

Currently, I have a Google Nest Thermostat Learning (I’m from Spain, so I have the European version with only 2 wires) connected to my gas boiler. However, I would like to replace it with a Sonoff NSPanel Pro and use it as a thermostat. Additionally, it would be nice if I could connect the panel to my A/C.

I’ve read about relays, but I’m a bit confused, as I’ve never worked with them before. I’m unsure if it needs to have Wi-Fi, eWeLink, Zigbee… If I have to choose, I prefer something that does not rely on the cloud and can operate on my local network, but I’m open to any option.

I believe I need to purchase the Sonoff SNZB-02 to control the room temperature, but I’m not certain.

I would prefer to exclusively use Sonoff products to avoid mixing different brands, and I’m uncertain if I also need a hub or similar device to control everything.

If you can assist me with this, I would be very grateful. Also, if you could explain how to connect the wires (in the cases where it is needed) with some diagrams or something similar, I would appreciate it.

In the future, I plan to incorporate light control as well, but that will be a later addition after I’ve successfully connected the gas boiler and A/C.

Thank you in advance!

The old NS Panel had a built in temperature, but no Zigbee and I don’t think the built in temperature was accurate enough.

I don’t know about AC but many boilers/heat-pumps have “EBUS”. I think it’s a German system or something so if you have a German boiler it is more likely. I have a Vaillant and it is connected to my iHost. Then you just can connect it via an EBUS adapter.
There is a daemon that needs to run all the time on a local computer to convert the EBUS to MQTT. I think this can be run on an iHost but not an NS Panel Pro.

It then sends out MQTT messages that the NS Panel Pro can see in Node Red. Alternatively you can just use standard switches (Zigbee is a bit better than wifi, but only a bit). More detail is very much dependent on how things are wired in Spain. If the boiler and AC just turn on/off when power is sent to a trigger like here then all you need is NS Panel Pro, ZigbeeTempZebsor and two switches.

Hi eerke, thanks for your fast response!

Wow, that looks so complicated for me.

My gas boiler is an Ariston (Italian), but I think it is probably similiar to a German boiler. I know that the Nest Thermostat acts as an “on/off” button with the two wires of my boiler, so maybe I just need a relay to do that. ¿Could you help me to find one that works with the NSPanel? I can attatch a couple of pictures of the instalation of my Nest Thermostat.

Note:”Caldera” means gas boiler in spanish.

(Connection to Nest Thermostat)

(Heat Link)

Also, do I need a Sonoff POWR3 High Power Smart Switch? I have read about it, but I don’t know if in my case I have to use it.

Thank you!

I have a nest learning thermostat ?3rd Gen. In fact 2. They don’t just connect with on/off but can do “OpenTherm” too, but if you’re not aware of that it probably isn’t used. I spent ages reading on it and ended up learning more about it than their support knows. You can daisychain devices under OpenTherm but you need a way for one to be a master and Nest don’t do that, so you end up having to decide between having multiple or OpenTherm and can’t do both at once.

I’m guessing where the diagram says NEST it is the wires to the front piece. I use it wirelessly and don’t have anything there, but I do have it controlling hot water.

Assuming you don’t want to mess about making it smart with an EBUS, in which case you’d need to read the manual for the device then all you need for the boiler is to put a Sonoff switch near the boiler (just power the switch with the power supply to the boiler; you may need wire splitters [I like WAGO rather than messing around with screwdrivers] and send the switches live from the switch output to the boiler switches live) and have a NS Panel Pro and thermostat. Is the AC control as simple too?

Is there any reason to replace it with a switch? Are you not satisfied? What is your ultimate goal?

Can you explain me whats is the difference between OpenTherm and “On/Off”. My gas boiler works to heat the water and also to control the heating of the radiators in my house.

You guessed right abou the NEST wires.

The problem that comes to my mind with putting a switch in the power supply of the boiler is that I need it to be always on to heat the water. Is there any problem with that? Or are you saying that I have to connect the switch to the 2 wires that are now connected to the Nest and a power supply to the switch? Could you put any link to a Sonoff swtich or relay that does that?

At the moment I don’t have the A/C (it’s a Daikin) connected to any thermostat, but I found this wire scheme in the manual to connect a thermostat:

I think it can also work with a switch, but I prefer to be able to control the temperature (and heat/cool) if it is possible:

Should it have something special to control that?

Thank you!!

The problem with the Nest Thermostat is that I can not control the heating and cooling system from the same device (at least with the european version).

My goal is to be able to control the gas boiler and the A/C with the same device/software.

OpenTherm is just slightly cleverer. Most boilers don’t have it. The main thing is that if the difference between target temperature and real temperature is greater the boiler will work harder and if the temperature difference is small it will relax, so you end up with a smoother temperature curve and use less energy. In your photo the Nest-Heatlink has connections named “OT” for OpenTherm, I think that is where the controls would attach, but most boilers lack it, it’s not used in the photo and unless you deliberately turned it on I don’t think it is relevant.
I’m guessing at your boiler you have

  1. Permanent Live
  2. Neutral
  3. Ground
  4. switched Live
    If so just
  5. add branch to Sonoff input
  6. add branch to Sonoff Input
  7. ignore
  8. cut/cap input end and connect boiler switches live input to the Sonoff output

You just need 2 of these: 1 for the heating and one for the AC.

Just keep in mind the intention is for lights so the current is limited to 6Amp and if the AC is more than this you might need a different switch and it is intended to go in a plastic back box and light so you need a box.

If you can find a Zigbee Basic they are ideal but they were often out of stock and I think they’ve stopped making them. I tend to resort to Zigbee Mini plus box.

If you can stick with Zigbee, rather than wifi, then the rules can be entirely local within the NS Panel Pro and its Zigbee network. You can set back up rules to turn off the AC when the heating turns on and turn off the Boiler when the AC turns on.

Perfect! I think I understand you, I will work in it and come back if I have any other doubt.

Just one last question, is there anyway to connect the 2 wires that are now connected to the Heat Link from the boiler and power the Sonoff Switch from a wall socket? At the moment, the 220V of the HeatLink is coming directly from a wall plug/socket (Neutral and Live-N/L) and the two wires coming from the boiler are connected to “ports” 2 and 3 in the HeatLink. I don’t know if doing that I can use the the two wires that are now controlled by the Nest as “On/Off” and keep the installation more simple.

Thank you for all!!

Yes. Just check there is a permanent live and neutral going to the boiler. If there is and as you don’t have a hot water tank attached I doubt you do you don’t need the wires. You may need to bypass the nest-heatlink if you don’t have permanent ones. In most cases I would just label the current wires and cap them. The Sonoff zigbee mini can take over the function of the Switched live but needs permanent live and neutral as does your boiler (probably). I am guessing that hot water appears if you turn on a tap so the boiler must need its own power supply.

Yes exactly, when I open the tap on hot water the boiler starts working. Right now I can only see that the boiler is connected to a wall socket, I don’t know how to check if I have a permanent live and neutral going to the boiler. Should I open the circuits of the boiler to check it? How can I identify those wires?


I found the electric scheme of my boiler:

Seeing that, I think that I can totally use what you told me.

Thank for all the help!!

If you have a plug you don’t need to do anything as you definitely have a permanent live and neutral. You do need to figure out where the switched live is though so you can connect the Sonoff output to it. It’ll be one of the two connectors that the Neat-Heatlink wires connects to. Probably the black and not blue one, but people do odd wiring so I’d read the manual. The other option is just to buy a 230V relay that is capable of controlling 230V too. connect input to Sonoff output and the two wires from the boiler to the relay output (normally open) in either direction). That might be easier if the boiler manual isn’t clear and they’re cheap. You could put the relay in the same box as the Zigbee Mini. I like putting relays in stuff when I am not sure about the original wiring.

Upon further reflection, I have the feeling that the solution you have planned is not the best idea. There is a high probability that it will not work as expected. What if there is damage to the boiler? Have you consulted a specialist about this?