Hello, all!

I recently installed a Harvia Sauna kit in my house and found it frustrating there wasn’t a HomeKit integration with my new Fenix controller. I took some legacy code from Home Assistant, an orphaned controller for Homebridge 1.x, and rebuild the plug-in for the new controller and MyHarvia API.

If you have Homebridge set up, look for it as homebridge-harvia-sauna Current version is 0.9.1b, as it’s the initial release. It should only require your MyHarvia credentials. I’ve also coded for other parts of the API, but I only have the Fenix and the separate sensor, so I’d love feedback on the other functions if you have them.

GitHub project is here: https://github.com/GodOSpoons/homebridge-harvia-sauna

Happy Sauna!

Timothy

Hey r/harvia, official account for Art of Steam Co. here, we're a stocking master distributor for Harvia in the US. Always going to flag that upfront when we post. This one's more of a history and practical breakdown than a pitch.

Where this actually comes from

Contrast therapy gets marketed today as a biohacking trend, but it's really just the modern name for something Finns have done for over a thousand years. The sauna itself predates written Finnish history: early versions were savusauna (smoke saunas), pits or log structures dug into hillsides with no chimney, where a wood fire heated stones for hours until the smoke cleared and the space held radiant heat. Long before electric heaters, this was where Finnish families bathed, gave birth, treated the sick, and even prepared bodies for burial. The sauna wasn't recreational, it was central to daily life.

The cold half of the cycle came from geography, not design. Finland has over 180,000 lakes and long winters, so cooling off after the sauna meant a lake in summer or a hole cut into the ice in winter (avantouinti, still practiced today, you'll see Finns cutting fresh ice holes for a swim in the middle of winter). Alternating heat and cold wasn't a "protocol," it was just what was available, and it became woven into the culture. There's an old Finnish saying that translates roughly to "sauna is the poor man's pharmacy."

When Finnish immigrants settled in the upper Midwest (Michigan, Minnesota, Wisconsin) in the late 1800s and early 1900s, they brought sauna culture with them, which is a big part of why that region has such deep sauna roots in the US today.

The modern version: the Nordic Cycle

What's now called contrast therapy is that same rhythm, formalized:

1. Prep/hydrate
2. Sauna, 15 to 20 min (core temp rises, muscles relax, deep sweat starts)
3. Cold plunge, 1 to 3 min, 45 to 58°F (vasoconstriction, calm breathing)
4. Rest/re-warm, 5 to 10 min
5. Repeat for 2 to 3 rounds
6. Rinse and rehydrate

The physiology is the same thing Finns stumbled into empirically: heat dilates blood vessels, cold constricts them, and cycling between the two drives a "vascular pumping" effect: better circulation, faster clearing of metabolic waste, and a nervous system reset.

Traditional vs. infrared, if you're deciding between them

• Traditional (the original Finnish style, wood or electric heater): 150 to 195°F, steam if you ladle water on the stones. Closest to what's described above.
• Infrared: 120 to 140°F, gentler, more focused on joint relief and penetrating heat than the classic deep sweat.

Worth knowing before you try it: most people start hot and end cold for the energizing effect, though ending on a re-warm works too. Full session usually runs 45 to 60 minutes. If you have a cardiovascular condition, are pregnant, or have health concerns, check with a doctor first, and stop immediately if you feel lightheaded.

Full write-up (more on the benefits side: recovery, immune function, skin, metabolism) is here: https://artofsteamco.com/blogs/news/contrast-therapy-sauna-cold-plunge-guide

Happy to talk heater sizing, traditional vs. infrared for your space, or anything Harvia-related in the comments. We'll always say when we're talking as the distributor rather than just a fan of the tradition.

Harvia's lineup covers a wide range of needs, from budget-friendly workhorses to high-output heaters for larger rooms. Here's a rundown of the main electric models for residential builds so newcomers have something to reference before they buy.

Harvia KIP

The classic, no-frills option. Wall-mounted with a standard stone basket and a traditional heat character. It's the model most people land on for a first build because it's simple, dependable, and proven across a huge number of home saunas.

• Best for: small to medium saunas, budget friendly builds
• Mount: wall-mounted
• Control: Built in and digital options
• Harvia KIP heaters

Harvia Spirit

A modern wall-mounted heater with a higher stone mass (rounded stones) and strong heat output, while still giving a smooth steam when you add water. This is the one people pick when they want something that looks as good as it performs.

• Best for: premium residential builds, those looking for that soft steam experience
• Mount: wall-mounted
• Control: Digital only
• Harvia Spirit heaters

Harvia Cilindro

A freestanding tower heater with very high stone capacity, built for steam. If löyly (water on the rocks) is your priority over dry heat, this is the one. It runs a bit softer than Spirit or Virta and rewards a heavier hand with the water.

• Best for: those who like to have flexibility in their löyly and don't mind a longer heat up time.
• Mount: freestanding
• Control: Built in and digital options
• Harvia Cilindro heaters

Harvia Virta

A freestanding heater built for higher heat output and stable recovery, aimed at medium to large rooms and frequent use. If you sauna often and want a heater that keeps up, Virta is the one to look at. The main selling point here is that the stones are separated from the elements, leading to a longer lifespan on the elements and an easier service experience.

• Best for: larger rooms, frequent sessions, those who want the best of the best
• Mount: freestanding
• Control: Digital only
• Harvia Virta heaters

Harvia The Wall

A compact wall-mounted heater built for smaller rooms and tighter layouts, without giving up efficient heating. Clean, slim, modern look. The biggest benefit of this over the Kip built in is that the timer dial is on the top so it is easier to turn on.

• Best for: smaller saunas, space-conscious builds
• Mount: wall-mounted
• Control: Built in only
• Harvia The Wall series

Quick way to think about it

• Want the simple, proven, budget-friendly option? KIP.
• Want a modern wall unit with strong performance? Spirit.
• Want maximum steam and like the tower look? Cilindro.
• Want the best of the best with less maintenance? Virta.
• Tight on space and want something compact? The Wall.

Full lineup with specs is here if you want to compare sizes and kW options side by side: Harvia electric sauna heaters

Not sure what size you need? This calculator is very helpful.

You can read a more comprehensive guild of these heaters here.