Flexit Nordic BACnet

Control a Flexit Nordic ventilation unit over BACnet/IP — from the command line or as a smart home device in Homey.

Features

Homey App (homey-app/)

A Homey SDK v3 app that exposes your Flexit Nordic unit as a native Homey device with full control and 16 sensor capabilities:

Controls

• Ventilation mode (Stop / Away / Home / High / Fireplace / Cooker Hood)
• Temperature setpoint
• Electric heater on/off

Sensors

• Temperatures: outside, supply, extract, exhaust
• Extract air humidity
• Fan speed % and RPM (supply + exhaust)
• Heat exchanger efficiency and rotor speed
• Electric heater power consumption (W)
• Air filter alarm

Automation

• Flow triggers: mode changed, filter polluted
• Flow conditions: is mode X, heater on, filter polluted
• Flow actions: set mode, set temperature, start fireplace/rapid ventilation, toggle heater

CLI Tool (flexit.py)

A Python command-line tool for direct device control:

python3 flexit.py status              # Full device status
python3 flexit.py mode home           # Set ventilation mode
python3 flexit.py temp home 22.0      # Set temperature setpoint
python3 flexit.py fireplace on        # Start fireplace ventilation
python3 flexit.py rapid --minutes 30  # Start rapid ventilation
python3 flexit.py heater on           # Toggle electric heater
python3 flexit.py fan status          # Show fan setpoints
python3 flexit.py filter status       # Air filter info
python3 flexit.py discover            # Scan for devices on network

Supported Devices

Flexit Nordic series ventilation units with BACnet/IP connectivity:

Model	Series
S2 RER / S2 REL	Nordic S2
S3 RER / S3 REL	Nordic S3
S4 RER / S4 REL	Nordic S4
CL2 RER / CL2 REL	Nordic CL2
CL3 RER / CL3 REL	Nordic CL3
CL4 RER / CL4 REL	Nordic CL4
KS3 RER / KS3 REL	Nordic KS3

Setup

Homey App

cd homey-app
npm install
npx homey app install

The app will discover your Flexit unit automatically during pairing. You can also enter the IP address manually in device settings.

CLI

pip install flexit_bacnet
python3 flexit.py --ip 192.168.1.128 status

How It Works

The Flexit Nordic units expose a BACnet/IP interface on UDP port 47808. This project communicates with the unit using:

• Homey app: node-bacstack for BACnet/IP transport
• CLI: flexit_bacnet Python library

Device discovery uses Siemens Unconfirmed Private Transfer (vendor ID 7) — the same protocol used by the official Flexit Go app.

Acknowledgements

• piotrbulinski/flexit_bacnet — The Python BACnet client library for Flexit Nordic units. This project's BACnet object map and protocol implementation were ported from this excellent library.
• fh1ch/node-bacstack — Node.js BACnet/IP stack used in the Homey app.

License

MIT