Free plans for building a Masonry Heater

I came across some free plans for building a Masonry Stove. If there was ever an application where thermal mass makes sense, this is it.

Masonry Heater Definition

A masonry heater is a site-built or site-assembled, solid-fueled heating device constructed mainly of masonry materials in which the heat from intermittent fires burned rapidly in its firebox is stored in its massive structure for slow release to the building. It has an interior construction consisting of a firebox and heat exchange channels built from refractory components.

Specifically, a masonry heater has the following characteristics:

• a mass of at least 800 kg. (1760 lbs.),
• tight fitting doors that are closed during the burn cycle,
• an overall average wall thickness not exceeding 250 mm (10 in.),
• under normal operating conditions, the external surface of the masonry heater, except immediately surrounding the fuel loading door(s), does not exceed 110 C. (230 F.),
• the gas path through the internal heat exchange channels downstream of the firebox includes at least one 180 degree change in flow direction, usually downward, before entering the chimney,
• the length of the shortest single path from the firebox exit to the chimney entrance is at least twice the largest firebox dimension.

More: http://mha-net.org

What is a Masonry Heater?

A masonry heater allows you to heat your home with wood in a unique way.

The main thing that distinguishes a masonry heater is the ability to store a large amount of heat. This means that you can rapidly burn a large charge of wood without overheating your house. The heat is stored in the masonry thermal mass, and then slowly radiates into your house for the next 18 to 24 hours.

If you burn wood fairly rapidly, it is a clean fuel. If you try to burn it too slowly, the fire will change from flaming to smoldering combustion. The burning process is incomplete and produces tars. Atmospheric pollution increases dramatically. This is important if you are planning an energy-efficient house. The average energy demand of your house will be quite low. For most of the time, it may require only 1 to 2 kW of heat. For most conventional wood stoves, this is below their critical burn rate, or the point where they start to smolder. Masonry heaters fill the bill perfectly. If you need even a very small amount of heat, such as between seasons when you simply want to take off the chill, you simply burn a smaller fuel charge yet you still burn it quickly. The large surface is never too hot to touch. You have a premium radiant heating system with a comfort level that simply cannot be equaled by convection or forced air systems.

More : http://www.mha-net.org