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AndrewJ -

Originally Posted by AndrewJ

I've just finished reading a book on the topic of home heating. "Natural Home Heating" by Greg Pahl

I think the best idea in the whole book was using masonry heaters. I've long wanted to build a passive solar home, but even then you need a backup heat source. Masonry heaters sound like the best option.

They were invented in Europe after traditional wood-stove use got rid of most all of the usable firewood on the continent. They're essentially a really HEAVY woodstove made of masonry. Most weigh in at 1-10 tons

The great thing about them is that you only fire them up twice each day. You simply burn a load of small wood (even twigs work!) with a lot of air (making a short hot fire) and all that masonry stores and releases the heat throughout the rest of the day.

Unfortunately, with all that weight they require a very solid foundation, and they're apparently pretty tricky to design.

Thanks for mentioning this. I heard about this maybe 18 years ago. Supposedly wood has the highest energy content *if* you can burn it efficiently.

While looking on the website you provided I found a software simulation page :

Simulation Software
http://mha-net.org/html/software.htm

And here's another masonry heater website that has the history I remember :

http://www.tempcast.com/

The Birth of the Masonry Stove
http://www.tempcast.com/planninguide/plan01.html

By the 15th century, wood shortages had begun to develop and European governments of the day realized an energy crisis was upon them. In the following two hundred years, efforts were made to conserve wood, with little success. However, as the energy crisis worsened into the 17th and 18th centuries, kings in Prussia, Sweden, Norway & Denmark ordered their craftsman and architects to produce better wood stove designs. This concerted effort produced radically new heat-storing masonry stove designs, which showed enormous improvement in efficiency and corresponding wood conservation.
Many of these designs survived and are still in use today in countries such as Sweden, Austria, Finland and Germany. Temp-Cast fireplaces closely follow original Scandinavian designs, which were later refined and used extensively in Finland.
Masonry stoves are still in widespread use throughout northern Europe and are highly regarded for their excellent heating abilities, safety features and environmentally positive aspects.
...
Recent testing in Finland shows that masonry heaters typically attain combustion efficiencies of 88 to 91%. The Temp-Cast 2000 fireplace was tested by an independent lab in April 1992, showing combustion efficiency of 94.4%, and heat transfer efficiency of 65.4%. (Ref. Omni Environmental Services Inc., "In-Home Evaluation of Emissions from a Temp-Cast 2000 Masonry Heater", May 8, 1992)

CarloSW2