How to use a sauna heater
Updated: October 2026
The carton is in the cabin, the electrician has already connected the supply, and you are facing the first heat with a stone basket and a ladle. This is how to use a sauna heater as a stone stove: warm it, throw a little water, and stop if you feel unwell. It is not a steam generator you fill like a kettle, and it is not a wiring project. Which box you bought is on the [3–6kW sauna heater comparison](/hub/steam-baths/3-6kw-sauna-heater). Temperatures and stone sizes below are manufacturer guidance, checked on 19 October 2026. A qualifying purchase can earn us a commission at no extra cost to you.
The carton is in the cabin, the electrician has already connected the supply, and you are facing the first heat with a stone basket and a ladle.
The carton is in the cabin, the electrician has already connected the supply, and you are facing the first heat with a stone basket and a ladle. This is how to use a sauna heater as a stone stove: warm it, throw a little water, and stop if you feel unwell. It is not a steam generator you fill like a kettle, and it is not a wiring project. Which box you bought is on the 3–6kW sauna heater comparison. Temperatures and stone sizes below are manufacturer guidance, checked on 19 October 2026. A qualifying purchase can earn us a commission at no extra cost to you.
Our top picks
| Badge | Product | Stones | Stated maximum | Sauna type | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Mxmoonant Mxmoonant 6 kW digital sauna heater | 18–20 kg extra | Not stated | Dry | 6.7 | about £297 | View offer |
| Alternative |  Mxmoonant Mxmoonant 6 kW sauna heater | 14–18 kg extra | Not stated | Dry | 5.4 | about £269 | View offer |
| Alternative |  LADECNERHT LADECNERHT 3.6 kW wet and dry heater | 6 kg included | 70 °C | Wet and dry | 3.5 | about £242.99 | View offer |
On this page
The first heat is for the smell, with the door ventilated
A new electric stove often smells the first time the elements come up to temperature. Harvia’s heater manuals, for stoves in that maker’s own range, tell you to expect that smell and to ventilate. Use that as guidance for a first run, not as a stopwatch for the Mxmoonant, LADECNERHT or DMETE in this set. For the first session, ventilate, keep children and pets out, and let the heater run before you judge the room. If the carton has no manual, you do not know the clearance to the bench or the wall, so ask the seller or a fitter before you build tight to the stove. Smoke, a plastic smell that stays, or a breaker that opens goes to the electrician. Kilowatts stay on the 3 kW versus 6 kW page.
Stones carry the heat you later throw water on
The stones hold the heat and turn a small splash into the burst Finnish saunas call löyly. Harvia’s guidance for many electric heaters is a 5–10 cm sauna stone, washed so the dust is not baked on, piled so it does not wedge into the elements. The £297 Mxmoonant asks for 18–20 kg and does not include them. The £269 model asks for 14–18 kg, also extra. LADECNERHT states 6 kg in the carton, which will not fill a basket specified at twenty. If your listing never mentions stones, ask the seller for the mass and size before the first water. The buying guide is where that missing line changes the price.
70 °C and 90 °C are both used, and they feel different
InfoFinland describes a usual sauna temperature of about 70–90 °C. Harvia’s temperature note says 80–100 °C can feel sharp even when you throw water, while 50–60 °C takes more water and feels softer. Those are two honest ways to run a stone stove. LADECNERHT is the only listing here that prints a range, and it stops at 70 °C, from 30 °C. On that stove, 90 °C is outside the title. The other pages in this set state no maximum. If there is no manual and no stated temperature, stop and get the document before you invent a setpoint.
A small ladle, then a break
Throw a ladle of clean water on the stones, not a bucket. InfoFinland’s public-sauna instructions are enough for a home cabin on this point: small amounts, and you leave if you feel unwell. More water on stones that are not yet hot mostly makes a wet floor. LADECNERHT’s how-to text does talk about releasing water during use, inside a 30–70 °C title. The Mxmoonant bullets call those heaters dry. Dry, in that wording, still usually means a stone stove you can splash. It does not mean a steam room you keep soaking. The circuit itself stays on the electrical supply page.
Common questions
What do I do the first time I switch it on?
Ventilate the room and expect a smell from a new heater as the elements warm. Keep people and pets out, and do not treat that first run as a finished bathing session. These amazon listings have no measured heat-up time. If smoke persists or a breaker opens, stop and call the electrician.
How full should the stone basket be?
Use sauna stones around 5–10 cm where the heater is an ordinary electric stone stove, washed free of dust, piled loosely so they do not wedge into the elements. The £297 Mxmoonant specifies 18–20 kg and the £269 model 14–18 kg, neither included. LADECNERHT includes 6 kg. If your page never states a mass, get that figure from the seller before you throw water.
Is 70 °C hot enough?
It can be, if the stones are hot and you use a little water. InfoFinland’s usual band is about 70–90 °C, and Harvia notes that 80–100 °C feels sharper while 50–60 °C feels softer and wants more water. LADECNERHT’s title stops at 70 °C. On that stove, 90 °C is outside the printed control. A higher air temperature is not automatically a better session.
How much water do I throw?
A small ladle of clean water on stones that are already hot, then a pause. A bucket cools the stones and wets the floor. Listings that never mention water do not give you permission to soak the heater. If you feel unwell, leave the room. Children stay clear of the hot stones and the casing after the timer has switched off.
How often do stones get restacked?
Restack at least yearly and throw away stones that have crumbled. Harvia’s family-sauna example is a change about once a year when the stove is used about twice a week. Heavier use shortens that. Dust left on new stones bakes on at the first heat, so wash them before they go in. These amazon pages do not print their own service interval.
What if the listing never states a temperature?
Follow the manual in the carton if there is one. If there is no manual, you do not invent a setpoint from a neighbouring brand. The 70–90 °C description is a public account of a usual Finnish-style room, not a promise from a blank listing. Ask the seller for the data plate and the instructions before the first bathing session.
Related pages
Sources
Public UK sources and the amazon.co.uk listing files named below, checked for this comparison on 19 October 2026. Page updated October 2026.
- Harvia, how to select heater power (retrieved 19 October 2026)
- Oceanic Saunas, wall heater volume table (retrieved 19 October 2026)
- Elec-Mate, sauna electrical installation (retrieved 19 October 2026)
- Sandwich Electrical, sauna heater supply (retrieved 19 October 2026)
- IET Wiring Matters, 3 kW load and a 13 A connection (retrieved 19 October 2026)
- IET, Part P in Scotland and Northern Ireland (retrieved 19 October 2026)
- Harvia Unio 3.6 kW, stated room volume (retrieved 19 October 2026)
- amazon.co.uk, Mxmoonant 6 kW listing B0DD3HCJS1 (retrieved 19 October 2026)