The Harvia Fenix Controller: Is Smart Sauna Control Actually Worth It?
If you are choosing an electric heater, sooner or later you have to pick a controller. Harvia's newest one is the Fenix. It is a glass touchscreen with WiFi built in, and an app that can have your sauna warm by the time you get home.
It is a nice bit of kit. But whether it is worth the money for your build is a different question. A lot of it comes down to where your sauna sits, and how much patience you have for app software. So this is an honest look at what it does well, where it struggles, and whether you actually need it.
The Fenix in place. Glass touchscreen, live temperature, WiFi built in. Photo: Harvia.
What the Fenix actually is
The Fenix is Harvia's smart controller. It replaces the older Xenio as their top model. The main difference is that WiFi is built in, so there is no separate module to buy and wire up. On the Xenio you had to add that yourself.
The panel is a 4.3 inch glass touchscreen. From one screen you control temperature, humidity (on Combi units), the heater, ventilation and lighting. There are three presets, called Mild, Cozy and Hot, and you can edit them or make your own. Harvia also gives it a "self-learning" function. It watches how your heater warms your room, and adjusts the timing so the sauna is actually ready when it says it is.
A quick spec rundown:
- Temperature range: 30-110°C (86-230°F)
- Display: 4.3 inch glass touchscreen, IPX4 (splash resistant)
- Connectivity: 2.4 GHz WiFi only. No Ethernet port, no external aerial
- App: MyHarvia 2 (iOS and Android)
- Panel size: 131 × 93 × 20 mm
- Door sensor: optional (FX002XW), enables the safe remote-start interlock
One more thing. If you already have a Xenio, the Fenix panel is a straight swap, with the same wiring. If you are building from scratch, you buy it as a full control unit. That means the panel plus a power unit, sized to your heater's kW.
What it does genuinely well
Two things stand out. They are the reason to buy a smart controller in the first place.
The first is preheating from your phone. An electric sauna needs 30 to 45 minutes to heat up. Starting it on the drive home, instead of walking down the garden, pressing a button, and walking back 40 minutes later, is genuinely useful. For most people this is the main reason to get one.
The second is the door sensor. If you buy the version with the door sensor (FX002XW), the app will not let you start the heater remotely unless the door is shut. That is good safety design. It stops the heater turning on with the door open, or with a towel left on the stones. If you have children, or other people use the sauna, I would treat the door sensor as a must.
The touchscreen itself is fine. It looks better than the old button panels, the presets are handy, and humidity control on a Combi unit is well integrated. None of it is life-changing, but it is done well.
Presets like Mild, Cozy and Hot are one tap on the panel. Photo: Harvia.
Where it struggles: reception and the app
This is the part the product page will not tell you. It is also the part that decides whether you will be happy.
First, a common myth. 2.4 GHz WiFi is the right choice here, not a weakness. 2.4 GHz travels through walls and over distance better than 5 GHz. For a building down the garden, it is exactly the band you want. Harvia got that right.
The real problem is what is missing. There is no Ethernet port and no aerial socket on the panel. So if the signal reaching your sauna is weak, and at a garden building 15 to 20 m from the house it usually is, you cannot plug it in with a cable, and you cannot add a better aerial. The only fix is to bring the network closer. That means a WiFi repeater, an extender, or a separate access point near the sauna. Budget for one, because most garden saunas will need it. Harvia's own troubleshooting notes say the same thing.
The reliable fix. Run a wire out to an access point by the sauna, then let the panel make one short WiFi hop.
Then there is the app. Here I would keep expectations low. Harvia's older app, MyHarvia for Xenio, sits at about 1.5 stars on the Apple App Store. Almost every review says the same thing. It connects for a second, then drops, and stays disconnected. One reviewer put it well: "very frustrating when you've paid for the WiFi add-on".
To be fair, the Fenix uses a new app, MyHarvia 2, not the one those reviews are about. So it is not fair to pin 1.5 stars on the Fenix itself. But an app is only as good as the connection under it. If you have not sorted the signal, the app is what you will stare at while it says "disconnected".
One smaller thing worth knowing. The panel can switch itself off during a session if it gets too hot, and will not come back on until it cools down. Mount it somewhere sensible, not high on a hot wall, and it is a non-issue. But it is in the manual.
The cost, and the licence nobody mentions
The standalone Fenix panel (FX001XW, the Xenio upgrade) costs around $666 USD. That is a good bit more than a basic controller. A full control unit with a power unit costs more again, depending on your heater's kW.
Then there is the licence. The touchscreen and on-site control work straight away. But the remote features, meaning starting the heater from your phone, scheduling, and the weekly timer, sit behind Harvia's MyHarvia Control licence. The good news is that it is a one-time fee, not a subscription. It is tied to the panel for its life, and the whole household can share it. New units come with a 3-month free trial, so you can test the remote features before you pay. Still, budget for it. A WiFi controller where the WiFi does not do the useful part for free is not quite the same thing.
None of this is actually new
It is worth saying plainly. The Fenix is not a breakthrough. App-controlled saunas have been around for years. Here in Poland, FFES (ffes.pl) has sold controllers with a phone app for a long time. Remote start, temperature, timer profiles, aromatherapy, evaporator and ventilation, all from your phone. The Fenix does the same job with a nicer screen and tighter integration.
And if you like doing things yourself, you can build the same thing for a fraction of the price. A Raspberry Pi Zero 2, a small Waveshare screen, an enclosure, a few temperature sensors and some cable will get you a networked touchscreen controller for well under $100. You get full control over how it behaves, no licence to buy, and no cloud service that can drop you. I built one for our own rental sauna. You can see how in how I built a smart sauna controller with a Raspberry Pi.
Nicely made, no question. But the touchscreen is the finish, not a feature only Harvia can offer. Photo: Harvia.
None of this makes the Fenix a bad product. It just means you are paying for convenience and finish, not for something only Harvia can do.
So do you actually need it?
Honest answer: probably not, but you might want it.
A sauna does not need a smart controller to be a great sauna. A plain Xenio, or even a basic timer and thermostat, heats the room just as well, costs less, and has nothing to disconnect. For many DIY builds, especially a sauna a few steps from the back door, you press the button, you wait, and you have your löyly. The phone never comes into it.
The Fenix earns its place in one situation. Your sauna is far enough from the house that preheating on the walk down is a nuisance, you will use remote start most sessions, and you are willing to sort the WiFi out properly. Get that right and it is a real comfort upgrade.
Worth it if:
- The sauna is a decent walk from the house, and preheating from your phone saves you a real trip
- You will add an access point near the sauna
- You want the door-sensor safety interlock
- You like the touchscreen and the humidity control
Skip it if:
- The sauna is a few steps from the back door
- Your WiFi barely reaches the garden, and you will not fix that
- You want the cheapest reliable way to heat the room
- Flaky app software would annoy you
If you do buy one
Two things will save you most of the trouble people complain about.
- Sort the signal first. Put a cheap access point near the sauna, ideally fed by a cable or a good mesh node. Do not rely on the house router reaching across the garden and through a foil-lined wall.
- Get the door-sensor version. The remote-start interlock is what turns a convenience into something safe. It is worth the small extra.
And keep it in perspective. The controller is the least important decision in your sauna. Ventilation, insulation, bench height and heater size all matter far more to how it feels. Get those right first. The controller is just how you turn it on.
If you are building the sauna this controller goes in, our architect-designed plan sets include heater sizing, ventilation and full construction drawings, so the important decisions are made long before you pick a controller.
Running a Fenix, or an old Xenio, in your own build? I would like to know how the app has held up for you. Leave a comment below.
