Standard Sauna Heater Stones

When water hits stones heated to glowing red, it seeps rapidly into those pores. The intense heat forces the water to expand and burst outward, producing a thick, powerful rush of steam. In Finland, this is called löyly, the soul of the sauna, and it’s what separates a good sauna session from a great one.

Stacking Your Stones

Irregular stones stack casually, but there are two rules worth following:

• Bottom layer: Use fist-sized stones to support the weight above and allow airflow around the heating elements.
• Top layer: Place smaller stones, roughly egg-sized, on top. The increased surface area means more contact with water and better steam production.

Leave a gap of two to three fingers between each layer to allow heat to circulate freely. Every six months, remove the stones and flip them over completely. This prevents dust and carbon from building up on the underside, which can reduce heat transfer over time.

Performance

Thanks to their porous structure, these stones can boost steam production by around 40% compared to smooth, non-porous alternatives. Because they absorb and release water quickly, you’ll find yourself adding water more frequently — which is exactly how a traditional Finnish sauna is meant to be used.

Made from natural volcanic basalt, the stones withstand extreme temperatures exceeding 600°C and will typically last 3 to 5 years with regular use before needing replacement.

Before First Use

Soak new stones in water and thoroughly scrub them before loading them into your heater. This removes any dust or debris from shipping and handling.

Important: Never use crystalline rocks such as quartz in your sauna heater. Crystalline stones can fracture violently when exposed to rapid temperature changes and water contact, creating a serious safety hazard.

• Box Size: 37 x 26 x 15cm
• Quantity: ~15-20 Stones
• Weight: 15KG

If an electrical item stops working within the warranty period, we’ll send you a replacement free of charge.

Every 6 months, remove all stones from the heater, flip them over and restack. This prevents carbon and mineral deposits accumulating on the underside, which reduces heat transfer over time.
Inspect stones for cracks, crumbling or significant erosion each time you restack. Discard any stones that are breaking apart — fractured stones restrict airflow and reduce heater efficiency.
Rinse stones with clean water during restacking to wash away loose dust and debris.
Check that airflow gaps between stones are maintained after restacking. Stones naturally settle over time, so re-spacing them keeps heat circulating evenly.
Replace the full set of stones every 3 to 5 years depending on usage frequency. Commercial or heavy-use saunas may require replacement sooner.
Only use clean water on your stones. Avoid pouring essential oils, beer or other liquids directly onto sauna stones — these leave residue that accelerates carbon buildup and can damage the heating elements. Use an aroma bowl or evaporator cup instead.