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Home/Multi-Zone Pro
The Multi-Zone Pro controller in an orange enclosure with its wiring harness

Multi-Zone Pro · Whole-system controller In development

Every zone of your system, in one place.

The Multi-Zone Pro connects to your Mitsubishi multi-zone system at the outdoor unit and brings the whole installation into your smart home platform. Every indoor unit as its own climate accessory, plus the telemetry that only the pros see.

Reservable now. We will email you when ordering opens.

Reserve yours
No payment to reserve No cloud, no account

How it connects ↓  ·  Will it fit my system? ↓

How it connects

One connection at the outdoor unit.

The Multi-Zone Pro wires to the communication wire at your branch box or outdoor unit. It draws its power from that pair, so there is no wall adapter and no extra wiring to any indoor unit. One device covers the whole system.

Multi-Zone Pro

Outdoor unit or branch box

Indoor units, every zone

Multi-Zone Pro

Outdoor unit or branch box

Indoor units, every zone

Will it work with your system?

Built for Mitsubishi multi-zone systems.

CITY MULTI

VRF systems, including installations with branch controllers. Scales from a single outdoor unit to large installations with multiple outdoor units on the same bus.

PUMY / P-series

Light-commercial systems that use the same two-wire transmission bus: the device wires in the same way, at the outdoor unit's terminals.

M-series, multi-zone

Heads wired through a branch box to a shared outdoor unit. Ported outdoor units are not supported.

Single-zone unit? The Serin Controller is the right device. Not sure which system you have? Ask us: a model number is enough.

Control

Control every indoor unit.

Every indoor unit on the system appears in your smart home platform as its own thermostat: power, mode, fan speed, and setpoint, per zone. Change one room without touching the others, automate them independently, and see each zone's live state come back from the equipment itself.

There is also a built-in web UI on your network for setup and a live view of the whole system, no Home Assistant required.

Climate · Home Assistant mode · room → set
Living RoomHeat · 72° → 74°
BedroomHeat · 68° → 70°
OfficeOff · 66°
Guest RoomOff · 64°
BasementFan · 65°

Telemetry

See what your system is actually doing.

Your outdoor unit tracks refrigerant pressures, valve positions, compressor current, and a dozen temperatures. These are readings that normally require a service visit to see. The Multi-Zone Pro reads them live and publishes every one to your smart home platform as its own entity.

HIGH-SIDE

208.4 psi

COMPRESSOR

58 Hz

6.2 A

ZONES CALLING

3 of 5

SUPERHEAT

8.6 °F

SUBCOOL

11.2 °F

Refrigerant circuit
  • discharge + suction pressure
  • LEV pulses, per branch
  • superheat + subcool
Compressor
  • operating frequency
  • compressor current
  • fan step
Temperatures
  • th1 / th2 / th3, per indoor unit
  • discharge temperature
  • room + setpoint, per zone
State & health
  • mode · run/stop, per zone
  • reversing valve + solenoids
  • fault codes, decoded

Sensor set varies by outdoor unit model. Values shown are illustrative.

Tech specs

The hardware inside.

Processor ESP32-S3 · Wi-Fi
Bus interface Dedicated transceiver for the two-wire transmission bus
Power Drawn from the transmission bus · no wall adapter
Integrations Home Assistant via MQTT discovery · more smart home platforms via firmware options
Interfaces Built-in web UI · REST API
Updates Over the air, on your network

Enclosure, dimensions, and final connector layout are published when the production run is final.

Good to know

Frequently asked questions.

Does it replace my remotes or central controller?

No. It joins the transmission bus alongside them. Your existing wall controllers, remotes, and any central controller keep working, and the Multi-Zone Pro shows their changes live.

Does it need Wi-Fi?

Yes: that is how it reaches your smart home platform and its own web UI. Everything stays on your network: no cloud, no account.

How is this different from the Serin Controller?

They take different views of the same system. The Serin Controller plugs into an indoor unit's CN105 port, one controller per unit. The Multi-Zone Pro connects once at the outdoor unit and covers every zone with a single device, plus system-level telemetry the CN105 port does not carry.

Is installation invasive?

Two wires to the transmission-bus terminals at the outdoor unit, the same terminals your indoor units are already wired to. The bus also powers the device. As with any work at the outdoor unit, power the system down first.

Will it work with the Serin Link?

Pairing with the Serin Link is planned: one knob on your shelf, every zone of the system behind it. Reserve either and we will keep you posted.

Can I request features?

Yes, please. The Multi-Zone Pro is in active development and feedback shapes it: tell us your system and what you want from it when you reserve.

In development

Reserve one from the first production run.

Tell us your system and what you would want from it: it will influence what ships, and you will be first in line when ordering opens.

Reserve yours Single zone? See the Serin Controller
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© 2026 Serin Labs · The firmware is free to install; see Licenses & Compliance.

Serin Labs is an independent business, not developed, endorsed, or certified by Apple Inc. or Mitsubishi Electric Corporation. Working on HVAC systems carries risk and may void warranties; proceed at your own risk. Apple, Apple Home, HomeKit, Siri, HomePod, Apple TV, iPhone, and iPad are trademarks of Apple Inc., registered in the U.S. and other countries. Mitsubishi Electric is a trademark of Mitsubishi Electric Corporation.