The heater sets the character of the room. Undersize it and the bench never gets warm; oversize it and you get sharp dry heat, a cycling thermostat and a cold foot well.
We size every heater from the adjusted room volume — glass, stone and cold external walls all count — and check the supply before an order is placed.
Sizing at a glance
- Rule of thumb
- 1 kW per m³ of room volume
- Glazed door
- Add 0.5–1.0 m³
- Full glass wall
- Add 1.5–2.5 m³
- Uninsulated stone
- Add 1.2 m³ per m² exposed
- Circuit
- Dedicated, with 30 mA RCD
What actually decides it
- 01
Stone mass matters more than wattage
Stone is what makes heat feel soft and hold through a session. A heater with a small stone bed reaches setpoint quickly and then swings.
- 02
The control unit lives outside the hot room
Every digital control we supply mounts outside, usually at the changing side of the door, on a low-voltage run kept away from the heater cable.
- 03
Clearances are not optional
50 mm to side walls, 120 mm to the front bench and 1100 mm to ceiling on a 6 kW unit. These are published on every product page so your electrician can plan around them.
Where to go next
Further reading
Questions
- What size heater do I need?
- Calculate the internal room volume, add for glass and uninsulated surfaces, then pick a heater whose stated range covers the adjusted figure. Send us the dimensions and we will do it with you.
- How much electricity does a sauna heater use?
- A 6 kW heater draws about 6 units for a first heat-up and roughly 3 units per hour held at temperature. A 90-minute session for two is under 10 units.
- Can you supply a heater without installing it?
- Yes, with the sizing calculation and installation drawing. We would rather you install it correctly than buy it cheaply and email us later.
Tell us the room.
Dimensions, the supply you have, and what you want to happen in it. We will come back with a system list and an indicative budget.