HUUM sauna heater stones are rounded olivine diabase stones made to go with HUUM electric heaters and wood-burning stoves. They store heat and make soft steam (löyly) when you pour water on them. HUUM recommends rounded stones for its open-frame heaters because they let the air flow through the stone bed, give milder steam, and heat evenly. Each box holds 15 kg (33 lbs) of stones, and you can choose between two sizes: Extra Small (Stones 12) at 3-5 cm (1-2 in), and Small (Stones 24) at 5-10 cm (2-4 in). The right size depends on your heater, so check the list below or your heater's manual before you order.
Rounded olivine diabase stones
HUUM describes its stones as made of olivine diabase, an igneous rock with a high thermal capacity that holds up to the extreme temperature swings inside a sauna heater. The rounded shape lets water evaporate gradually, which gives milder steam than sharp-edged stones. The stones are also designed to resist cracking, and the rounded finish suits the clean look of HUUM heaters.
Pick the right size and quantity for your heater
The Extra Small 3-5 cm stones are for the CLIFF and STEEL heaters, including their Mini versions. The Small 5-10 cm stones are for the DROP, HIVE, HIVE Mini, CORE, and HIVE Wood stove models. Quantities depend on the heater: for example, HUUM lists about 75 kg (5 boxes) of Extra Small stones for the CLIFF, about 150 kg (10 boxes) of Extra Small stones for the STEEL, and about 55 kg (4 boxes) of Small stones for the DROP. See the tables below for more. These are approximate, so always confirm the stone size and amount in your heater's manual. Please check with us if you are not sure which size your heater takes.
Preparing and laying the stones
According to HUUM's care guide: wash the stones before first use, because dust from manufacturing and shipping can affect air quality and heater efficiency. Rinse them under running water, and let them dry fully before you place them. Put the larger stones at the bottom for airflow, mixing sizes in layers, and place smaller stones on top for even steam. Do not over-pack the heater, so that air can flow. Before the first real use, heat the stones once to normal sauna temperature and let them cool slowly, without throwing water on them, to protect against thermal shock. Remove and inspect all the stones from time to time, and replace stones that are eroded or noticeably lighter than before. HUUM suggests replacing all stones at the same time. Use natural stones made for sauna heaters, not decorative stones.
Rounded olivine diabase sauna heater stones for HUUM heaters. Choose Extra Small (3-5 cm, for CLIFF and STEEL) or Small (5-10 cm, for DROP, HIVE, HIVE Mini, CORE and HIVE Wood). 15 kg (33 lbs) per box. Rounded stones give milder steam, high heat capacity, and resist cracking.
1 box of rounded olivine diabase stones, 15 kg (33 lbs)
Your choice of size: Extra Small 3-5 cm or Small 5-10 cm
Milder, softer steam
The rounded shape lets water evaporate gradually, which gives the milder steam HUUM recommends for its heaters.
High heat capacity
Olivine diabase is an igneous rock that stores a lot of heat and holds up to the extreme temperature swings in a sauna heater.
Resists cracking
The stones are designed to resist fracturing, which matters because broken pieces can block the heater's air holes.
Two sizes to match your heater
Extra Small 3-5 cm stones suit the CLIFF and STEEL, and Small 5-10 cm stones suit the DROP, HIVE, HIVE Mini, CORE, and HIVE Wood stoves.
Built for open-frame heaters
Round stones let air move through the stone bed in HUUM's open-frame heaters, which gives more even heating.
Packed by weight in 15 kg boxes
Each box holds 15 kg (33 lbs), so it is easy to work out how many boxes your heater needs. We are an authorized HUUM dealer.
