Replacing Honeywell cm907


I want to replace a Honeywell CM907 by a hestia pi device (I live in Europe), does anyone got some feedback ? Should I take the hestia pi HVAC or the normal one ? At the moment, have not air conditionning at home (but maybe in the future), I think that the HVAC could fit but I need confirmation …

Thanks in advance for your help/answers


Could you provide a diagram or schematic of the wiring. A photo of the wiring would also help :slight_smile:


You can find some info on this pdf (info on wiring are on page 7) :

Thank you

CM907 is a battery operated device. HestiaPi is not. It needs mains connection (110-220V AC).
You need to check that these wires are available behind your existing thermostat. They usually do.
If you have mains then, yes, HestiaPi will probably work with your home too.

OK, I can get the mains connection so I can buy the HVAC version of hestia pi, it will work ?

Thanks for your help !

Page 7 shows various wiring options for various houses. All are supported but we can give you detailed wiring instructions for HestiaPi if you know which is your house option. A photo would help too. How many wires come out of the wall?

Ok this is what I have at home :


The switch down is for the light so nothing to deal with the cm907

Yes it looks good. If you have a multimeter please select the AC Voltage option and measure voltage between Black and Blue. It should be around 220V.
Next short Black and Brown and wait to check if the heating turns on. Please note that some systems have a delay before the heating actually turns on.
If you don’t have a multimeter we are still pretty certain that any HestiaPi (HVAC or EU) would work.
Ask any questions here before you proceed with your purchase and read the full product page in advance :slight_smile:


I have received my hestiapi touch, if I have well understood the Black wire should be connected in the L contact on the hestia board and the blue wire should be connected in the N contact. My question is : where the brown wire should be connected (is it the first contact on the top on the 4 other connectors on the other side) ?


The brown wire should go to the H (Heating) contact.
Good Luck!


I received this PCB and I do not see where the H contact is. I have already tested the two contact on the left for L and N and everything works, the device boot and load the OS. So where is the H contact is ? I suppose on the right side, the first from the top ? I did not find info on this PCB on the website. Most of the PCB only have four contacts with H/W/L/N on the same line. So there is twice L/N contacts on this board ? Please it will be nice if you can me the pinouts for these 6 contacts.


Sorry, I didn’t realise you have the HVAC version. The documentation is incomplete, thats why it is not published yet.
You will need first a short wire between L (top on the left side) and the top of the right side (labelled R below).
Then connect the heating wire (Brown) to the third from the top of the right side (labelled W below).

Second (Y) and fourth (G) are for cooling and fan control respectively.
Sorry about that.