HUUM UKU Sauna gives you full control over your HUUM sauna heater, including
the settings the official HUUM app for Homey leaves out — target humidity
above all.
What is this app?
An unofficial, third-party companion app for HUUM sauna heaters with the UKU WiFi controller. It talks directly to HUUM’s cloud API — the same one the official HUUM mobile app uses — so everything that API exposes is available on Homey too, not just the subset the official Homey app covers.
Why this app exists
The official Homey app for HUUM can’t set target humidity, even though HUUM’s own mobile app can. I reported that gap to Athom in June 2025; as of today it still hasn’t made it into the official app, so I built this one instead.
What can it do?
- Settable target humidity (the official app only shows it, can’t set it)
- A no-water alarm for the steamer
- A safety cut-out / fault alarm
- A remote-start-blocked sensor — separate from the door sensor, shows when the UKU’s own remote-safety confirmation is blocking a start
- A time-remaining readout, plus a Flow trigger shortly before the UKU’s own auto shut-off
- 3 profiles (temperature + humidity presets), startable from the device tile, a Flow, or the dashboard widget
- A scheduled start with optional auto-off. HUUM’s API has no booking endpoint, so this runs entirely on Homey — it survives a restart, and a start missed by more than 30 minutes is dropped rather than fired late
- Per-session energy and cost, fed by a kW estimate or by a measured-power value you push in from a Flow (e.g. from a Shelly)
- A dashboard widget with live status and quick-start buttons
- Steamer and light are auto-detected during pairing, so you only see the controls that actually apply to your setup
Flow Cards
When (triggers):
- The sauna reached its target temperature
- Remaining time drops below (x) minutes
- Maximum heating duration almost reached (based on the UKU’s own auto shut-off timer, not the target temperature)
- The current temperature changed (Homey’s own measure_temperature defaults
only offer threshold cards, not a plain “changed” one — this app adds it) - Remote start became blocked / available
- A sauna session ended (with duration, temperature, humidity, energy and
cost tokens)
And (conditions):
- Remaining time is / is not below (x) minutes
- A start is / is not scheduled
- Remote start is / is not blocked
Then (actions):
- Start the sauna at a temperature and humidity
- Start the sauna with a profile
- Schedule a sauna start today / tomorrow at [time] with a profile
- Cancel the scheduled start
- Save the current settings as a profile
- Set the sauna’s measured power (for the energy statistics, e.g. from a Shelly via a Flow)
(Plus everything Homey generates itself from the standard capabilities — turn
off, set temperature/humidity, the light, door/alarm triggers, and so on.)
Setup
Pairing uses the same email and password as the HUUM app. Everything runs against HUUM’s cloud (sauna.huum.eu) — there is no local/LAN protocol for the UKU, so this can’t be a fully local app. The app requests no special Homey permissions; no data leaves your Homey beyond what talking to HUUM’s own API requires.
About this app
I built this for my own sauna after reporting the target-humidity gap to Athom and not seeing it get picked up. Built with Claude’s assistance.
Available in the Homey App Store:
Support the development
Building, testing and maintaining this app takes a lot of time, and I’m happy to keep doing it. If it helps your smart home run smarter and you’d like to say thanks, a coffee (or a beer) is always appreciated.
