Heater stones should be of a material that is as heavy as possible, dark in colour and large in size for them to be able to store as much heat energy as possible. Heater dealers sell stones that are specifically intended for use as heater stones, and that come from well-known suppliers, so their composition and suitability are guaranteed. Stone materials suitable for heater use include peridotite, olivine and olivine diabase. Surface rocks collected in nature are not suitable for heater use.
Ceramic “stones” and soft soapstones must not be used. They do not store enough heat when heating up the heater. This may result in the heater overheating, which in turn leads to the heating elements breaking.
The heater stones must be stacked in the heater in accordance with the installation and user instructions of the heater. Heater stones are available in two sizes.