Masonry wood heaters

A stone mason friend of mine was telling me about a new product he is building. He is a dedicated artisan with a real feel for his materials. In his own back yard he built a masonry oven that he cooks in and he tells me it retains the heat for days after the fire is removed.

He recently constructed a masonry wood heater for a client which replaces conventional oil heat which was costing the client $800.00 to $1000.00 for each heating season. In addition to the heat he also incorporated a cooking oven in the heater so that it has a dual purpose.

These days when many are concerned about air quality wood burning fires are often considered a contributor to the erosion of air quality. However, designed in a special way these wood burning heaters burn clean and do not contribute to poor air quality.

Most wood heaters damp the fire down so that the wood takes longer to burn which does cause a lot of smoke and particulate matter. Or, they might be a fast burning open fireplace where most of the heat goes up the chimney.

With these heaters you burn a hot fire that consumes all the wood in a very hot fire over a shorter period of time. Because it burns hot there is very little smoke and particulates except when just starting the fire.

The way these masonry wood heaters work is rather than the heat going up a chimney, the hot gases from the fire travels through a convoluted series of channels in the masonry on the way out the chimney. This allows the heat to dissipate into the masonry.

The numbers on this are as follows.

  • - The average house uses 200,000 to 300,000 BTU’s of heat per day.
  • - One pound of wood releases 8,000 BTU’s.
  • - One load of wood typically about 40 lb and burning in about one and a half hours, would release 320,000 BTU.
  • – With the masonry capturing virtually most of this heat there is enough stored heat to heat the typical home for a full day.

This is not a new theory but a wonderful radiant heat that has a long history including in the Roman baths where they heated floors and walls with the hot gases from wood fires. The same system has been used to heat bed platforms in China, Korea and Russia; and the Finnish have been doing this for centuries. Find out more history at this link

There are suppliers like my friend Danny from Savino Masonry (whose work you can see in the photos above and on his website) and he recently sent me photos of a Bio-Fire Tiled Masonry Wood Heater he just built. There are other forms like the soapstone wood heaters by Tulikivi which you can reach through this link.

Another supplier is Rocky Mountain Environmental Technologies at this link They provide a kit that would get you started comprising the firebox and flue. You would still require a mason to construct and finish it for you.

Another interesting addition to this that you could heat your domestic hot water would be to insert a water heating loop into the masonry of the fireplace. It could provide a preheat at least and when the fireplace is warm could provide all the hot water you might need. These stainless steel loops are available at Hilkoil by following this link.

In his own words Danny of Keystone Masonry describes it like this: “the quality of life and pleasure of having this central gathering place in the home is priceless”

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