How Masonry Heaters Work . . .

The masonry heater works by burning a full firebox at high temperature for a couple of hours; the flue gases passing through channels surrounded by a masonry facing (brick, stone, stucco etc.). This absorbs most of the heat produced rather than losing the heat up the chimney like traditional open fires or ‘steel box’ stoves. The stored heat then radiates gently out over the following hours giving a pleasant warming “like a rock warmed by the sun” long after the fire has gone out. One burn is usually enough but two burns in 24 hours can deal with the coldest weather. Because the wood is burned rapidly, it burns clean and flue deposits are almost eliminated (see Environment).

The flow of heat in a Tempcast masonry stove.

The flow of heat in a Tempcast masonry stove (flue omitted).
(click for a larger image)

The higher the thermal mass of the facing material, the better it works. The best material of all is Soapstone but this is not readily available in Australia. If bricks are used they must be solid or the cavities filled with mortar as work proceeds. They key is getting as dense a facing as possible to absorb the heat.

The facing is a minimum 100mm thick skin of masonry that absorbs the heat from the fire and radiates it out into the house without itself becoming too hot for comfort (see How Hot? )

It’s great to sit all day with your back against a masonry heater as we did when snowed up in an Italian mountain lodge. In Russia the top of the heater was where the children slept in the winter.

The Tempcast photo gallery shows the endless variety of materials and styles that can be used to create the facing of your heater. If you don’t wish to do the work yourself then you will need to find a good bricklayer or mason. We chose to build our own facing using double height bricks by Boral, in a colour that matched our house. There are some photos on the page showing our heater and more ideas on the Links page.

The style is something for you to decide. We raised our heater up a foot and built a bench hearth to sit or put our feet on. This is where you can exercise your creativity (within the constraints of the core design of course).