Steam & Oak Holvi 350 Thermowood Barrel Sauna (Gas, Electric or Wood-Fired) - Ø2.27m, 2.38m high / Gas: Botnia 81 with safety pack

Steam & Oak Holvi 350 Thermowood Barrel Sauna The Holvi 350 is a 3.5 metre barrel laid out in three spaces: a 60cm covered terrace at the door, a 1 metre changing room with its own benches, and a hot room about 1.9 metres long behind a tempered, tinted glass door. The changing room is what makes a barrel this size work through a British winter. You undress and cool down in a dry, sheltered room, the hot room stays hot because its door opens into the changing room rather than outdoors, and wet towels stay out of the heat. It comes in two widths, Ø1.97m or the taller Ø2.27m, both in 46mm thermowood staves with stainless steel bands. Every part of the layout can be changed. The barrel can be built without the changing room for a longer hot room, or without the terrace, and we will confirm the hot room size for any layout before you order. Which width? Ø1.97m. 2.08 metres high, a 4.61m³ hot room. Quicker to heat and a smaller heater does the job. Door 70 x 160cm. Ø2.27m. 2.38 metres high, a 6.19m³ hot room. More headroom on the upper bench, which is where the heat is, and a little more room to lie down. Door 70 x 180cm. Why the bands are stainless A barrel only stays round and tight because the bands keep the staves pressed together. Timber shrinks each time the sauna is heated and dries out, then swells again through a wet British winter, so the bands work constantly and need checking and re-tightening over the life of the sauna. Ordinary steel bands eventually rust, and rust runs down the timber and stains it. Stainless steel does not, and on the Holvi it is standard. What thermowood actually does Thermowood is timber that has been heat treated at around 200°C rather than chemically preserved. The process breaks down the sugars and resins that fungus feeds on and permanently reduces how much moisture the wood can reabsorb. The practical result outdoors is timber that moves less through wet British winters and resists rot without chemical treatment, in a structure that depends on staying tight. Choose your heater at checkout Shell only. The complete sauna, you source your own heater. Harvia Cilindro PC70 6.8kW. The Cilindro pillar heater with its tall column of stones and controls built into the heater. Harvia rate it for rooms of 6 to 10m³. Harvia Cilindro PC70XW 6.8kW WiFi. The same heater with MyHarvia app control, so you can start it from the house. Supplied with the Harvia door sensor, which the electrical sauna standard requires before any heater can be started remotely. Harvia Cilindro PC90 9kW. The classic Cilindro pillar with its tall stone column, 90kg of stones, controls built into the heater. Harvia rate it for rooms of 8 to 14m³. Harvia Cilindro PC90XW 9kW WiFi. The same heater with MyHarvia app control, so you can start it from the house. Supplied with the Harvia door sensor, which the electrical sauna standard requires before any heater can be started remotely. Most sellers leave that part off the quote. Harvia M3 wood fired. The classic Finnish log burning stove, rated by Harvia for rooms of 6 to 13m³. No electrics at all, no standing charge, and the ritual of building the fire. Supplied with a stainless steel chimney, and we confirm the chimney route with you before you order. Harvia M3 SL wood fired, through wall feed. The same stove, loaded through the wall from outside the hot room, so you feed the fire without letting the heat out or carrying logs past bathers. Sizing the heater. Harvia size heaters on the room volume, then add 50% for solid log walls and about 1.2m³ for every square metre of glass, because both soak up heat that an insulated panel would not. On the Ø1.97m Holvi 350 the hot room behaves like about 8m³, and on the Ø2.27m like about 10m³. So the narrower barrel gets the 6.8kW Cilindro and the wider one the 9kW. The heater list at checkout only shows the heaters that suit the width you pick. We would rather sell you the right heater than the cheapest one. Tell us where the barrel is going and how you plan to use it, and we will confirm the choice with you before you order. Also available with gas Pick a gas option at checkout and the sauna ships gas ready: ventilation built for gas, plus a FinSteam gas heater package that runs on a standard UK propane bottle. No electrician, no chimney and no fire to tend. It heats in around 15 minutes from a dial. Botnia 81. Our standard 8.1kW gas heater. Everything you need to run the sauna. Aurora 81. The premium version of the same 8.1kW heater, with a better finish and detailing, oxygen depletion auto shut off and flame monitoring. With the safety pack. Adds the Njord heat shield and the Halo guard rail. The heat shield lets the heater sit closer to the timber wall, and the rail stops anyone brushing the hot stones. If you have children, guests, or you rent the sauna out, choose this one. Without the safety pack. Heater and stone cage only. Talk to us first, because in a curved barrel the wall leans in above the heater and we will

Product information updated: 29 Oct 2026