Sauna Home Assistant – How to Integrate Your Sauna
Connecting a sauna to Home Assistant is one of those projects that sounds niche until you do it, then you wonder how you lived without it. You get remote control, temperature monitoring, automated preheating, and the smug satisfaction of your sauna greeting you when you walk through the door.
Not every sauna makes this easy. Some heaters have native Home Assistant support. Others need creative workarounds. This guide covers all of it so you can figure out where your setup falls and what to actually do.
Can You Add a Sauna to Home Assistant?
Short answer: yes. Longer answer: it depends on what you want and what heater you have.
Home Assistant can connect to your sauna in two broad ways. It can control the sauna (turn it on, set a target temperature, schedule preheating). Or it can monitor the sauna (know when it’s running, alert you when it reaches temperature, track usage over time). Some setups do both. Others only do one.
If your heater is from HUUM, Harvia, or Saunum and was manufactured in the last few years, you’re probably in native integration territory. If you have an older electric sauna or an unsupported brand, you’ll need one of the workarounds covered below. Either way, some level of Home Assistant sauna control is achievable for nearly every electric sauna on the market.
Safety First: What Can Go Wrong
Before you touch anything, understand what you’re dealing with. Electric saunas run on 230V or 400V mains voltage. The heater’s built-in control unit exists for a reason: it prevents overtemperature conditions, manages duty cycles, and keeps the bather safe. Bypassing or modifying that control chain is not a trivial hobby project.
European-manufactured electric saunas are certified to SFS-EN 60335-2-53, the standard covering heaters for sauna cabins. Modifying the control unit can void your warranty and affect insurance coverage. Start with non-invasive methods: they’re safer, reversible, and they’ll teach you how your sauna behaves before you commit to anything more involved.
Your Integration Options, Ranked by Effort
Here is how the main approaches stack up, from cleanest to most hands-on.
1. Native integrations (HUUM, Harvia, Saunum)
Your heater talks directly to Home Assistant via its own API or local network protocol. No extra hardware on the heater itself. This is the best experience if your heater supports it.
2. Infrared control (BroadLink RM4)
A BroadLink hub learns your sauna’s existing IR remote signals and lets Home Assistant fire them on demand. Works with any infrared-controlled sauna. No wiring changes required. Limitations: no temperature feedback loop, so Home Assistant cannot confirm the sauna actually responded.
3. Temperature sensor detection
A Zigbee or WiFi temperature sensor placed near the sauna vent detects the sauna running by temperature rise. Home Assistant uses this to infer state, trigger automations, and send notifications. No control, but full awareness. Completely non-invasive.
Native Integrations: HUUM, Harvia, and Saunum
HUUM
HUUM electric heaters are among the most Home Assistant-friendly options available. The UKU control unit supports local API access, which gives you on/off control, temperature setting, and current state. You can tie sauna control into the rest of your home: preheat based on calendar events, sync with solar production surplus, or trigger from a voice assistant. HUUM also supports a door sensor, which is useful for safety automations and usage tracking.
Harvia
Harvia’s Xenio WiFi gateway exposes a local HTTP API that Home Assistant can hit directly. Unlike cloud-only solutions, this keeps your sauna on your local network without depending on a vendor server. Harvia supports multiple control points (sauna door, control panel inside the cabin, the app), and the Xenio gateway pulls all of that into one interface.
The Harvia integration gives you scheduling, on/off control, and temperature readouts. The main limitation is that Harvia’s API is less documented than HUUM’s, so some reverse engineering may be required depending on your specific model.
Saunum
Saunum takes a different approach with its climate sensor integration. The heater is named and tracked by sauna type, which lets Home Assistant apply different heating profiles depending on whether you’re running a Finnish dry sauna or a more humid session. If you want granular control over climate conditions rather than just on/off, Saunum’s approach is worth exploring.
No Native Option? Try Infrared Control
If your heater doesn’t have a documented Home Assistant integration, infrared control is the most widely applicable workaround.
The BroadLink RM4 Pro (or the older RM Mini3) sits outside the sauna, learns your existing remote’s signals, and lets Home Assistant fire them over the network. The setup process is straightforward: put BroadLink in learning mode, point your sauna remote at it, capture the power-on, power-off, and any temperature commands you use.
What you get: on/off control, basic scheduling through Home Assistant, and integration with presence detection. You can set your sauna to start preheating when you leave work, for example.
What you don’t get: temperature feedback. Home Assistant fires the command and assumes the sauna responded. If the remote has line-of-sight issues or the signal doesn’t reach, you won’t know until you physically check.
One safety note: some enthusiasts add a thermal-rated relay between the IR blaster and the heater as a hardware failsafe. This is worth considering if you’re using IR control for something you leave running unattended.
Detect Sauna State Without Touching Wiring
This approach is the safest starting point, and honestly the one I recommend for most people.
Mount a Zigbee temperature sensor (Aqara T1, Sonoff SNZB-02, or similar) on or near the sauna’s vent. The sensor reads ambient air temperature outside the cabin. When the sauna heats up, vent exhaust temperature climbs noticeably. When it cools, the temperature drops.
A Home Assistant template sensor or trend sensor watches this number and infers state. A simple example: vent temp 5°C (9°F) above ambient means heating has started. Vent temp above 60°C (140°F) means ready to use. Home Assistant can trigger lights, send notifications, or log usage automatically.
This gives you zero control over the heater. You cannot start or stop the sauna this way. But you get full awareness: you know when it turns on, when it’s ready, when it’s been running too long, and when it finally cools down. For most people who just want to know their sauna is running and be notified when it’s ready, this is enough.
The Aqara sensors are small, cheap (around 15-20 euros), and run on a coin battery for months. Placement matters: position the sensor where it catches direct exhaust air, not in a draught-free corner where temperature changes are muted.
Practical Automations to Set Up
Once your integration is running, here are the automations worth the five minutes they take to set up.
Preheat before you arrive: Trigger the sauna to start heating when you leave work or enter a geofenced zone. If you use the vent sensor approach, add a precondition: only trigger preheat if vent temp is below 30°C (86°F).
Notification when target temperature is reached: Home Assistant watches the temperature sensor and sends your phone a notification when the vent temp crosses your threshold. Walk straight to the door knowing the sauna is ready.
Hallway lights signal sauna state: A smart bulb or LED strip shifts to warm red when the sauna starts heating, then to warm white when it reaches target temp. You can see sauna state from anywhere in the house.
Auto shut-off after extended cooling: If the vent temperature stays elevated past your typical session length, Home Assistant sends an alert. Native integrations can also shut off the heater directly.
FAQ
Can I control any sauna with Home Assistant? In some way, yes. Native integrations cover HUUM, Harvia, and Saunum heaters with full control. Infrared covers any sauna with an IR remote. Temperature sensor detection works universally. The question is whether the method matches what you want to achieve.
Does using Home Assistant void my sauna warranty? It depends on the manufacturer and what you modify. HUUM and Harvia explicitly design their systems to allow third-party integrations, so using Home Assistant through their documented APIs does not void the warranty. Bypassing the control unit entirely (infrared, temperature sensors) means zero modification to the heater. If you start rewiring the control board, you are on your own.
What’s the cheapest way to make my sauna smart? A BroadLink RM4 Pro (15-20 euros) plus your existing remote. You get on/off and scheduling with zero installation. Add a 15-euro Zigbee temperature sensor if you want status awareness. That’s a 35-euro smart sauna setup. Native integration is free if your heater already supports it, but the hardware (HUUM UKU, Harvia Xenio) costs more upfront.
Can I put a temperature sensor inside the sauna cabin? No, and you shouldn’t try. Standard consumer sensors are not rated for sauna temperatures, which regularly exceed 80°C (176°F) at the bench and 100°C (212°F) near the ceiling. The vent sensor approach gives you everything you actually need without subjecting your hardware to conditions it was never designed for.
Where to Start
If your heater is HUUM, Harvia, or Saunum: install the native integration and skip the workarounds. If it’s older or unsupported: start with the vent temperature sensor approach. It’s safe, reversible, and teaches you how your sauna behaves before you commit to anything more complex. Add a BroadLink later if you want control on top of awareness.
Don’t start with a direct wiring modification on a brand-new heater without understanding what the safety standard covers. Read the SFS-EN 60335-2-53 section on third-party controls. Ask your manufacturer whether their warranty is contingent on using only their control unit.