Sauna stones for an electric heater
Updated: October 2026
When you buy sauna stones for an electric heater, the exposed or enclosed elements determine what will fit. A dark volcanic rock is not suitable merely because it appears beside a 230 V heater on amazon.co.uk. You need the manual’s permitted material, diameter and total kilograms, followed by a loose stack that covers the elements without bending them. Start with our [sauna stones comparison](/hub/steam-baths/sauna-stones), but reject any listing that cannot answer those three model-specific requirements.
When you buy sauna stones for an electric heater, the exposed or enclosed elements determine what will fit. A dark volcanic rock is not suitable merely because it appears beside a 230 V heater on amazon.co.uk.
When you buy sauna stones for an electric heater, the exposed or enclosed elements determine what will fit. A dark volcanic rock is not suitable merely because it appears beside a 230 V heater on amazon.co.uk. You need the manual’s permitted material, diameter and total kilograms, followed by a loose stack that covers the elements without bending them. Start with our sauna stones comparison, but reject any listing that cannot answer those three model-specific requirements.
Our top picks
| Badge | Product | Stone size | Pack weight | Electric heater named | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  SAUNOM Saunom 15 kg vulcanite | 2–3.5 in or 2.54 cm | 16.06 kg | Yes, in the title | 7.5 | about £141.18 | View offer |
| Alternative |  WILLOWYBE Willowybe 16 kg box | About 2.5 cm | 15.85 kg | Not in the bullets | 6.9 | about £128.30 | View offer |
| Preis-Tipp |  Toyvian Toyvian 1 kg 2–3 cm | 2–3 cm | 1 kg | Heater in the bullets | 5.5 | about £11.19 | View offer |
On this page
The elements set the permitted stone size
Many conventional electric heaters use stones around 5–10 cm. Harvia’s AC3000 is a concrete example: 20 kg of split-face olivine diabase in that diameter, intended to stack with air spaces. It is a useful benchmark, not a rule for every heater.
Slim heaters demonstrate the exception. HUUM specifies 3–5 cm rounded stones for CLIFF and STEEL, while DROP, CORE and HIVE use 5–10 cm rounds. Stones that are too small can settle deeply or enter spaces the designer meant to remain clear. Stones that are too large may sit above the elements or tempt you to force the coils apart. Do not hammer oversized stones into shape. If your box does not naturally fit within the manual’s range, exchange it.
One retail box may not provide the complete fill
After diameter, check mass. A small wall heater may take about 20 kg, but exposed tower designs use far more stone. HUUM’s examples run from roughly 40 kg for CORE to 55 kg for DROP, around 75 kg for CLIFF and roughly 250 kg for a large HIVE. These are manufacturer examples, not estimates for an unbranded heater.
A 1 kg bag at £11 looks cheaper than a 20 kg box at £55, yet twenty of those bags would cost about £220 before delivery. The three 2–3 cm light products in this comparison are Toyvian at 1 kg, Veemoon at about 1.04 kg and Lurrose at ten pieces with a table weight of 151 g. Each is a top-up at most, assuming the diameter is accepted. Fill to the level and mass shown in the manual. The sauna stone buying guide explains how to compare cost per kilogram without losing sight of compatibility.
Cover the elements without loading or wedging them
Heater stones should support one another, not hang their weight from the elements. Place them individually so air can pass through the charge while the elements are screened as the manual illustrates.
In many open-element heaters, correctly sized pieces naturally sit around the coils, but they must not bend, spread or trap them. Our step-by-step stacking guide covers rinsing, hand placement and commissioning.
Harvia advises against ceramic stones and soft soapstone in relevant conventional heaters because unsuitable pieces may store too little heat and allow the elements to overheat. Use ceramic media only where the heater maker explicitly approves the exact type. A UK electric sauna heater is ordinarily a 230 V appliance, but the stones themselves have no power source. Toyvian and Lurrose listing tables say “ac”, which is a misplaced catalogue field. It does not show that the stone was tested at UK voltage.
Watch for listings that miss the size in either direction
Toyvian, Veemoon and Lurrose all state 2–3 cm stones. That is below the 5–10 cm range common in many conventional manuals and below HUUM’s 3–5 cm slim-heater example. A title saying “electric sauna” cannot replace the model documentation.
The opposite problem appears in Willowybe reviews. Its table suggests dimensions around 2.5 cm, yet several reviewers describe stones too large to fit between electric elements. One UK reviewer said roughly half the box was unusable and could not reasonably be broken with a hammer.
Saunom’s listing gives 2–3.5 inches in a bullet and 2.54 cm cubes in the table. Its heavy pack and electric-heater wording are useful only once that range is confirmed. Our best sauna stones UK comparison weighs those listing and review conflicts.
Common questions
Can I use 2–3 cm stones between heating elements?
Only when the manufacturer expressly permits that size. Several amazon.co.uk listings in this comparison offer 2–3 cm pieces, but many manuals specify larger stones. Small pieces can settle into unintended gaps and alter airflow. Do not experiment on the basis that a product title says “electric”; obtain the heater’s model-specific instructions first.
Should sauna stones touch the elements?
Correctly sized stones may sit around elements in designs with an open stone space, but they must not load, bend or wedge the coils. Place stones individually so they support each other and preserve airflow. Follow the manufacturer’s diagram because element guards, supports and acceptable contact differ between heater designs.
Can I use ceramic stones in an electric sauna?
Only in a heater that explicitly approves the ceramic product. Harvia warns against ceramic stones in relevant conventional models because unsuitable media can change heat storage and contribute to element overheating. A specialist heater designed for ceramic media does not establish permission for another appliance.
Why does an Amazon stone listing say “power source: AC”?
It is a catalogue error or generic product field. A bag of stones is passive and has no electrical power source. “AC” does not mean the material was tested at 230 V, is suitable for UK installation or fits a particular heater. Compatibility comes from material, dimensions, mass and the heater manufacturer’s approval.
What should I do if the stones are too big?
Do not hammer them, wedge them between elements or run the heater with an incomplete unsafe stack. Photograph the delivered size, compare it with the listing and manual, and ask the seller for an exchange or refund where appropriate. If an element has already bent or the safety cut-out trips, use a qualified electrician.
Related pages
Sources
Heater-maker guidance, UK product-safety pages and one UK shop price. Listings checked 16 October 2026. Prices on amazon.co.uk move.
- Harvia, changing sauna stones (retrieved 16 October 2026)
- Harvia, heater stones (retrieved 16 October 2026)
- Harvia support, which stones (retrieved 16 October 2026)
- HUUM electric sauna heaters (retrieved 16 October 2026)
- GOV.UK, General Product Safety Regulations 2005 (retrieved 16 October 2026)
- Consumer Rights Act 2015, section 9 (retrieved 16 October 2026)
- Collingwood Surgery, sauna in pregnancy (retrieved 16 October 2026)
- Sauna Timber, rounded olivine diabase 15 kg (retrieved 16 October 2026)