They are very efficient and produce very little pollution. They burn so clean that they are exempt from the ban on burning wood (even in Washington). They fall into the super-low emission category. Masonry heaters are safer than wood stoves because there is no risk of fire with creosote.
Once the fire is turned off, there is no part of the outside of the heater that isn't safe to the touch, as the surface temperature ranges from 100 to 180 degrees F. In fact, it's quite safe and comfortable to sit with your back to the masonry facade to absorb the heat. Many older European stoves had a built-in sleeping platform at the top of the heater and some people today incorporate a heated corner or bench for sitting in their designs. As the outside of the heater gets hotter and hotter, it emits more and more radiant heat to the living room.
The metal-clad heater didn't become popular in Sweden, but it became the most popular type of masonry heater in Finland. Many of the most important members of the MHA have personal experience with heaters that have been turned on under these conditions. These two features, which are unique to masonry stoves, ensure that all combustible gases burn in the heater, producing heat, not creosote. Once the fire is extinguished and no more heat is absorbed, the heat stored in the mass begins to migrate to the outside of the masonry heater.
In addition, there is a long tradition of masonry heating in Europe, and the manufacturer or manufacturer of the heaters is not expected to assume responsibility for abusive operation, as may be required in the United States. Brick is still used, but in modern heaters the firebox itself is made of high-temperature refractory bricks, the rest of the heater is made of cheaper bricks. Masonry heaters channel the hot exhaust of the fire through a winding path of chimneys integrated into the mass, heating every ounce of that enormous structure. Masonry takes longer to heat up than metal; but once heated, the heater will radiate this heat for a much longer period of time and at a much lower temperature than what a metal stove would use (metal is only hot when there is fire inside the stove and for a short period thereafter).
The first mention of the use of metal to cover the heater is found in a Swedish patent application dating back to 1878.If you hire a masonry heating professional to build one for you, plan to pay what you would pay for a new car, between $10,000 and $30,000 or more for something extra large, truly personalized and one-of-a-kind. Instead of a cast-iron wood stove that would need to be constantly powered, I installed an efficient and less labor-intensive masonry heater in my house. You may have heard of masonry heaters under different names, such as Russian fireplaces, German stoves, Finnish fireplaces, or even Kachelöfen. Clay mortar was used in the construction instead of cement; the chimney outlet was often placed at the base of the heater so that the heater could be held upright due to movement caused by thermal expansion and contraction.
Recently, three series of tests have been carried out: one on masonry chimneys and 2 sets on masonry heaters. Traditional Finnish stoves closely follow the look of round Swedish tile heaters, usually built with bricks.