Green Building Elements

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Author’s note: the following article on home heating is the seventh in an eight-part series. If adding thermal mass to your house isn’t realistic, another approach is to install a massive heater. That is to say, the heater contains the thermal mass your house may lack.

Clean and Super-Efficient Wood Heating
Super-efficient wood burning heaters with lots of mass are called by many names: masonry stoves, russian stoves, finnish stoves or finnish fireplaces, mass heaters. Though mass heaters may look like traditional fireplaces, they’re actually very sophisticated heating devices.

Burning wood in a mass heater doesn’t involve feeding in wood a few pieces at a time. The wood is added all at once, lit, and burned as quickly and as hotly as possible. Because of the high combustion temperature, there’s virtually no smoke. Combustion is so complete that, with the exception of a bit of smoke released when the fire is first started, most of what comes out of the chimney is carbon dioxide and water vapor.Most Comfortable Wood Heat
Mass heaters have numerous advantages over other wood burning appliances. The stove contains enough thermal mass to capture all the heat of the intense, clean burn and radiate it back slowly and gently over a specific time period, usually 18-24 hours. From one firing to the next, the mass heater ranges from very warm to warm, but is never hot to the touch.

The airtight combustion pathway is made entirely from refractory materials that can take high heat. This pathway is long enough to capture as much combustion heat as is desirable. (Why not capture all the heat? It turns out that leaving some heat in the exhaust gasses is important, or the heater won’t draw, that is, direct combustion gases up the chimney rather than into your home.)

If all this sounds inviting, read further. Operating a mass heater is more involved than setting a thermostat, but isn’t hard or time consuming. The last and final article in this series can help you decide whether a mass heater makes sense for you.

Previous Articles in this Series:

• Heating Your Home: Why Woodstoves Aren’t the Answer
• Heating Your Home: Why Fireplaces Don’t Heat
• Heating Your Home: Thermal Mass
• Heating Your Home: Forced Air
• Heating Your Home: Heat 101
• Heating Your Home: Radiant Heat, Wood Heat

Photo credit: Temp-Cast Enviroheat LTD