Wood Masonry Heaters (Russian/Finnish fireplaces)

Masonry heaters look like fireplaces, but they work differently. Their main working principle is to store a large amount of heat (from a rapidly-burning fire) within their structure and to slowly radiate it into the home all long the day.

Masonry heaters are also called Russian and Finnish fireplaces (they have been used in Europe and Asia for centuries).

Masonry heaters take advantage of their large thermal mass (tones of mass, in many cases) in the form of stone or bricks to absorb the heat and to release it slowly over a period of 12–20 hours.

How it works

Most masonry heaters are site-built and their core and surrounding walls involve high thermal firebrick and masonry components (stone, brick or tile). Their core includes a firebox and a long net of heat exchange channels, able to handle temperatures above 1,000°C (2,000°F).

Masonry heaters and environment

Russian/Finnish fireplaces are very environmentally clean appliances. Environmentally, they are much better solutions than traditional stoves and fireplaces. The relatively short-time fires in which they are based, produces very little air pollution and creosote buildup (in the chimney).

Masonry heaters typically reach a combustion efficiency of 90%, and if located in sunny places they will be able to absorb the sun's heat, which increases their efficiency.

Masonry heaters and Fuels

Most masonry heaters burn wood, though other types of fuel may also be used.

Advantages

Masonry heaters are a unique way of heating a home. They have many of the advantages of radiant heating, and are highly prized for the comfort they provide, higher than that of forced air systems, or fireplaces and stoves. Besides, they are a good environmental solution, not requiring certification from organizations as the American EPA.

Masonry heaters only require a fire or two per day (instead of multiple loads), which is also an operational advantage over other wood heating appliances.

Disadvantages

Russian/Finnish fireplaces are relatively high-cost appliances, demanding relatively high spaces. Another disadvantage relatively gas stoves, inserts and other heater is that they cannot provide a quick heating. If the house or room is cold, it will be necessary some hours before reasonable temperatures are obtained...

Operating a masonry heaters

A masonry heater demands wood (or other solid fuel…) like wood fireplaces or wood stoves. But, on the other hand, you just have to fuel a masonry heater one or two times a day. If you need a small amount of heat you just have to burn a small amount of wood…

Even in winter and in periods of high needs, you just have to make one or two fires each day, to get all the heat you need. The wood is burned very quickly, and the fire goes out, but the stored heat will continue to be released into the house for many hours.

Installation and price

There are a wide variety of masonry heater styles and designs. There are small models taking up little space (the space that a wood or pellet stove occupies), but most models are medium and large-

Besides, larger models involve a high investment: costs of $5000 and more are common, though all depends on the model, design, chimney costs…

There are multiple plans and kits available, but the installation and construction process demands experience and know-how. Masonry heaters are a do-it-yourself job.