Wood-fired or electric: which sauna heater is right for you?

Choose electric if your site has a mains supply that can take it. It heats up faster, needs no firewood, no one has to feed it, and you can set it on a timer. In a commercial setting that makes it far easier to manage, which is why it's what we recommend.

Choose wood-fired if there is no power where the sauna will sit: a beach, a field, a lakeside, an event. It runs completely off grid. It is also the more traditional, romantic option, and some people choose it for exactly that.

An electric sauna heater is a big load, so the supply matters more than anything else. These are the heaters and supplies we fit:

Build	Heater	Supply
10ft container sauna	9‑10kW	3 x 16A three-phase, or 40A single-phase
20ft container sauna	20kW	Two circuits, 3 x 16A and 3 x 25A, three-phase only

So a 20ft electric sauna needs a three-phase supply; a 10ft can run on single-phase if the site can give it 40A. Ask your electrician what your supply can take before you choose. If the answer is no, wood-fired is the way round it.

Electric. A heater runs at full power while it heats up, then at about half to hold the temperature. So for a 4-hour session with a 1-hour heat-up, at 25p a kWh:

• 10ft container sauna: 10kW x 25p x 1 hour, plus 10kW x 25p x 4 hours x 50%, comes to about £7.50.
• 20ft container sauna: 20kW x 25p x 1 hour, plus 20kW x 25p x 4 hours x 50%, comes to about £15.

Put your own tariff in place of the 25p and the sum still works.

Wood-fired. Budget about £25 of firewood for a long day in a horsebox sauna or 10ft container, and about £37 for a 20ft. Most of it goes on the heat-up. Buy kiln-dried wood from someone local and try a small bag before you order a load: damp wood smokes and can add the best part of an hour to the heat-up.

Either way, fuel is one line in the running costs. The rest is in what a container sauna costs to run.

A wood-fired heater needs someone to look after it. Lighting it is quick once you have the knack, and then it wants feeding: a refill after the first ten minutes, another after the next ten, then every fifteen to twenty minutes for as long as you are open. Keep the vent open at least a little while the fire is going, because the fire and the people both need the air.

It also needs a little upkeep that an electric heater doesn't:

• Every month: take the stones out and hoover under the little hatch. It does wonders for the draw.
• A chimney sweep: clean the flue, under the hatch and the firebox, and check the heater and flue for wear or damage.
• Smoke or soot on the rain cap usually means the flue liner has slipped up. When it's cold, lift the top section of flue off and slide the liner back level with the top, then get a sweep in.

Our video tutorials show lighting, feeding and looking after the fire step by step.

• A fixed site with mains power (a gym, a padel club, a hotel, a farm with a supply): electric.
• A beach, field or lakeside with no supply: wood-fired.
• A horsebox sauna going to events: usually wood-fired, because you can't count on a hook-up at every pitch.
• A 20ft container on single-phase power: wood-fired, or upgrade the supply first.
• You want the fire itself to be part of it: wood-fired, and plan the time to look after it.

Not sure what your site has? Start with what a sauna site actually needs, then talk it through with us.