Hot Water/Central Heating Boiler Control and Automation

Thread Starter


Joined Dec 5, 2021
I working on a number of home automation projects in Japan. I would like to be able to control the majority of the electrical systems in my house and be able to provide this as a service to others.

Currently in the house I have a seperate hot water boiler and central heating boiler. Both are running from kerosene (light oil) and have a small electronical display. Unfortunately when the power cuts out or there is an electrical fault in the house, both boilers will turn off and not turn back on again unless the button is pressed manually. This can be a huge problem during the winters in Hokkaido, Japan when the outside temperature can be -10C and some houses left attended. This can potentially lead to frozen water pipes and considerable damage. I would like to be able to restart these remotely after a power cut.

The hot water boiler is a Chofu IB-3964DF
The central heating boiler is a Mitsubishi VKH-80KU

There are similar boilers made by another manufacturer called Corona. I assume that they all use the same type of interface for communication, but this is something I don't have any experience with.

The potential difference between the two contacts is 12V. Polarity doesn't seem to matter, the display powers up and functions when swapping the wires over.

From the remote control you can turn the boiler on/off, set the water temperature and create schedules.

Does anyone have an idea of the communication used and whether it can be easily interfaced through a microprocessor such as an ESP8266 or ESP32?



Thread Starter


Joined Dec 5, 2021
Would a WiFi relay module, such as this, meet your needs?
I don't think that such a relay module would work. The display is powered by the boiler and there is some kind of digital communication between the two using the same wires. The boiler tells the display the current water temperature and the display can change the water temperature and turn the boiler on/off.

I have thought about hooking the boiler upto an ESP32, but would need an interface to bring the 12V down to 3V that the module can handle. But then I have the issue of guessing the communication protocol which is difficult without an oscilloscope.


Joined Oct 2, 2009
That is an interesting and challenging project.

If you wish to be successful with projects such as this I would recommend investing in a good digital oscilloscope.