Smart Heatpump

As outlined previously, Mitsubishi Heatpumps don't have smart integrations built-in, and their supported solution is massively backordered, so I set out to make my own.

I already have a Home Assistant setup running many things in my house which made the bulk of this much easier.

I also had an ESP8266 lying around.

What I didn't have was the right connector.

What it should have looked like:

What I did:

The bottom left connector that looks mangled was cut with an exacto knife to fit into the port. That plus an extra jumper header made it a 5-port connector.

Wire those up to an ESP8266 on the TX and RX pins and flash ESPHome with the Geoff Davis' esphome component and you can add your heatpump to Home Assistant!

Working Too Well

After 2 months of that working it suddenly decided to give up one day. The ESP device was still controllable through the network but the heatpump stopped responding to changes. The heatpump got stuck on heat full blast and all I can say is that thankfully June was cold this year.

After a bit of debugging, I had to pull the smart device and revert back to the MHK2 solely.

Next Steps

I have more to say about my future plans and other previous work I did.

• Switching the ESP8266 for an ESP32
• Updating the library to support UART passthrough to enable dual control from the MHK2 and the smart home
• I do actually have the right JST connector now, so maybe use that instead of MacGyvering it.

But those will have to be written later.