[APP][PRO] wMBUS Water Meter — Kamstrup Multical 21 / FlowIQ 2200

Apps
1

A community Homey Pro app that decodes encrypted wMBUS telegrams from
Kamstrup Multical 21 and FlowIQ 2200 water meters via MQTT, and exposes
them as fully-featured Homey devices with leak/burst alarms, flow rate,
flow temperature, and Energy dashboard integration.

Features

  • AES-128-CTR decryption (ELL II, CI=0x8D) with CRC-16/EN-13757 verification
  • Status flags: dry, reversed, leaking, bursting (exact bit mapping from wmbusmeters)
  • Capabilities:
    • meter_water — total consumption (m³), integrated with Homey Energy
    • measure_water — current flow rate (L/min, derived from delta)
    • measure_temperature — flow temperature (°C, when available)
    • alarm_water — main leak/burst alarm
    • alarm_water.dry — dry pipe (separate, non-critical)
    • alarm_water.reversed — reversed flow (separate, non-critical)
    • alarm_water.bursting — pipe burst (separate)
  • App-level MQTT configuration (broker URL, credentials, topic)
  • Device class watermeter — shows up in Homey Energy dashboard
  • Full Danish + English localization

Requirements

  • Homey Pro (firmware ≥ 5.0.0)
  • An MQTT broker reachable from Homey (e.g. MQTT Server app on Homey itself)
  • A wMBUS radio gateway publishing raw hex frames to MQTT
    • Reference implementation: Heltec LoRa32 V3 + ESPHome (firmware available in repo)
    • Compatible with any gateway that forwards raw hex telegrams
  • AES-128 key for your meter (request it from your water utility)

Installation (current — via CLI)

git clone GitHub - KMaansson/com.koledanmark.wmbus: kamstrup multical 2200 water m3 to homey · GitHub
cd com.koledanmark.wmbus
npm install
homey app install

Submitting to Homey Community Store soon — will update this thread when available.

Repository & Documentation

Hardware tested

  • Kamstrup Multical 21, T1 mode, 868 MHz (Denmark — Greve Vandværk)
  • Should work with any MC21 / FlowIQ 2200 broadcasting T1 telegrams

Status

Stable. Running 24/7 in my own setup since May 2026.

Feedback

Please report bugs and feature requests via GitHub Issues:

2 Likes