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Heating and cooling · Choose and design your heating · thermal-8Consider a masonry heater or rocket mass heater
Masonry heaters burn a short, very hot fire and store the heat in a large mass that releases it slowly, which suits well-insulated houses with steady loads. Rocket mass heaters are a DIY variant with much less regulatory recognition.
How
- Understand the trade-off: DOE notes masonry heaters reach about 90% combustion efficiency and release heat over 12 to 20 hours, but cannot heat a cold house quickly.
- Plan the foundation: a masonry heater is very heavy and needs structural support designed in from the start.
- In earthquake areas, ask the structural engineer to design the heater's foundation and restraint for seismic loads.
- Note that in the US masonry heaters currently do not need EPA certification, but they still must meet building and fire codes.
- For rocket mass heaters, confirm with your building authority and insurer before building, as many have no approval path for them.
- Pair either one with a quick-response heat source for cold starts.
Safety: Same fire and CO risks as any wood appliance. Some insurers ask about wood heaters; check with yours.
Do these first
Sources
- Wood and Pellet Heating. U.S. Department of Energy, Energy Saver, accessed 2026-11
- Choosing Wood-Burning Appliances. U.S. Environmental Protection Agency, accessed 2026-11