With the cost fossil fuels and electricity constantly rising, many people have returned to more natural home heating systems. Firewood is plentiful in this part of the world, but there are legitimate concerns about air pollution from burning wood. Also conventional metal stoves get very hot and can be a fire hazard.

Northern Europeans long ago developed a more efficient and safer way of heating with wood. The contraflow masonry heater was designed to provide safe and reliable radiant heat. A quick hot fire for a few hours each evening warms a large mass of masonry, which provides steady radiant heat throughout the night and into the next day. There are numerous designs for this type of heater, but the main idea is an unimpeded supply of combustion air and a somewhat convoluted path for the exhaust gases to transfer as much heat into the masonry as possible before exiting the chimney. A damper on top of the chimney is closed before going to bed to keep the remaining warmth from continuing up the chimney after the fire is out. The entire unit must be centrally located and the chimney kept within the heated space as much as possible. If properly designed and operated, it is a very efficient and minimally polluting heat source. An unobstructed air intake ensures clean burning and a well built chimney ensures a good draw, which greatly reduces creosote buildup in the chimney. Also, a secondary combustion chamber helps burn all the combustible gases driven out of the wood when heated. These gases normally go right up the chimney and add to the creosote buildup and air pollution.

The refractory core for a masonry heater is available in prefab kit form from a few different suppliers and can be faced with brick or stone to suit the homeowner. It could end up weighing several tons, so a properly built foundation is essential.

Combined with intelligent passive solar design and a solar in-floor radiant heat system, a masonry heater can be a big part of the heat source in a natural home and a joy to gather around on a cold winter night. Nothing says home quite like a fire in the hearth.

Keary Conwright is a natural home designer and builder living in Otter Point

Published in the Rural Observer, December 2012