serin labs

Your mini-split, on your network.

The Serin controller is a compact package that plugs into the port your Mitsubishi mini split already has, giving you real two-way control. Open firmware, no subscription.

Buy the controller — from $35 Build it yourself
  • 5.0 · 13 reviews
  • Free US shipping
  • Open source on GitHub
The Serin Controller — a compact Wi-Fi controller board with the CN105-to-Grove cable attached

I use Home Assistant

ESPHome firmware, curated configs, and a YAML generator. Every mode, vane and sensor lands as an entity.

Flash ESPHomeSetup guide →

I use Apple Home

HomeKit-compatible firmware pairs straight into the Apple Home app. Siri, scenes and automations, no bridge.

Flash HomeKit Setup guide →

Running in about fifteen minutes

  1. Check your model

    Nearly every Mitsubishi indoor unit since 2010 has the port.

  2. Flash in the browser

    Plug in over USB, pick your platform, wait two minutes.

  3. Plug into CN105

    Power off, seat the cable, tuck the board inside, power back on.

  4. Add it to your home

    It appears as a thermostat in Home Assistant or the Home app.

Check your model Read the full setup guide →

The lineup

One per indoor unit — or one Multi-Zone for the whole system.

The Serin Controller beside the optional wireless room sensor

Serin Controller

from $35

Pre-assembled, no soldering. Add the wireless room sensor to control from the temperature where you sit.

Buy →
The Serin Link rotary knob display on a desk stand, showing 74° and cooling

Serin Link

Soon

A rotary knob display that sits on a desk or shelf. Pair it with a Serin Controller — or any ESPHome climate device — and set temperature and mode without a phone.

Get notified →
The Multi-Zone Pro controller in an orange enclosure with its wiring harness

Multi-Zone Pro

Soon

M-, P- and City Multi systems: every indoor unit controlled, plus full diagnostics. Matter-compatible, so HA and Apple Home both work.

Join the waitlist →

Why the CN105 port beats the alternatives

Cloud adapters cost five times as much and stop when a server does. IR blasters fire commands into the air and never hear back.

Serin / CN105 Cloud adapter IR blaster
Cost from $35, or ~$18 DIY ~$180 ~$15
Feedback Real-time, two-way Via cloud, delayed None at all
Works offline Yes — 100% local No Yes
Firmware Open source Proprietary Varies
Serin / CN105
Cost
from $35, or ~$18 DIY
Feedback
Real-time, two-way
Works offline
Yes — 100% local
Firmware
Open source
Cloud adapter
Cost
~$180
Feedback
Via cloud, delayed
Works offline
No
Firmware
Proprietary
IR blaster
Cost
~$15
Feedback
None at all
Works offline
Yes
Firmware
Varies

Multiple indoor units? Each has its own port and needs its own controller.

Check your model → Buy the controller — from $35