Masonry Magazine February 1983 Page. 23
BIA Technical Notes
on Brick Construction
Brick Institute of America 1750 Old Meadow Road, McLean, Virginia 22102
19D
1983
BRICK MASONRY FIREPLACES
PART I-RUSSIAN STYLE HEATERS
Abstract: Brick masonry heaters may be used instead of conventional fireplaces to provide efficient supplemental heating for residential buildings. The design, detailing and construction of brick masonry fireplaces with baffle systems for combustion gases are discussed. Information regarding building code compliance, operation and the accessories required is presented with the basic principles by which these heaters provide supplemental heat for buildings.
Key Words: brick, buildings (codes), design, energy, fireplace, heating, masonry, mortar.
INTRODUCTION
There are many ways of improving the energy efficiency of fireplaces. Fireplace energy efficiency may be increased by providing glass screens or exterior air for draft and combustion; altering the shape of the firebox for increased radiant heating; incorporating baffles within the mass of the fireplace through which room air may be circulated for increased convective heating; or combinations of these features. These features, along with the proper design, construction and operation are discussed in Technical Notes 19 Revised, 19A Revised, and 19C, and are used to increase the efficiency of the wood-burning fireplace for heating the building or room. By altering the design of the fireplace to change the fire- box shape and to replace the smoke chamber with a baffle system, greater heating and wood combustion efficiencies may be achieved. These alterations in the fireplace design result in a baffled brick masonry fireplace or brick masonry heater.
The brick masonry heater is a concept that has been used for centuries in Northern and Eastern Europe. Various styles of brick masonry heaters are often referred to as "Finnish" or "Russian" stoves, although they are used in many other countries such as Belgium, Germany, Switzerland, Sweden, The Netherlands and Norway. The basic principles used to obtain the high heating and combustion efficiencies are: 1) controlled air intake to the combustion chamber or firebox; and 2) a baffle system through which hot combustion gases are circulated. The combustion gases circulated through the baffle system heat the walls of the heater, which in turn heat the room. The basic concepts of design, construction and operation are simple, but there are several concerns which must be addressed to insure safety and durability. Two basic designs of brick masonry heaters are discussed in this Technical Notes: the "Russian Stove" with a horizontal baffle system, and the "Russian Stove" with a vertical baffle system. Other Technical Notes in this Series address the "Finnish" or "Fountain Style" brick masonry heater and modifications which may be applied to result in contemporary designs of brick masonry heaters.
These heaters are often referred to as stoves because as originally designed and built, they had provisions which permitted portions of the heater to be used for baking and cooking. This was done by circulating the hot combustion gases through baffles surrounding a brick oven and under exposed metal plates which were used for cooking. Such provisions are not practical for modern lifestyles because of the difficulty in controlling temperatures, thus the baking and cooking features are not addressed in this Technical Notes. However, the cooking features may be a consideration for designing and con- structing an outside barbeque or cookstove.
GENERAL
Operation
Operation of a brick masonry heater is simple. The firebox is loaded with about 20 lb (44.0 kg) of wood. The fire is ignited. Once good combustion of the wood begins, the firebox door is closed and the air intakes are adjusted to the proper setting so that good combustion is maintained. The combustion gases exhaust from the rear of the firebox, circulated through the baffle system, warm the entire mass of the brick masonry heater and then are exhausted to the exterior of the building through a conventional chimney constructed on top of the heater. The fire usually burns about 30 min when properly seasoned wood is used, and thus the firebox should be reloaded with 20 lb (44.0 kg) of wood four times in a 2-hr period for maximum heating. This procedure usually results in the brick masonry heater being sufficiently heated to keep a room, about 2 400 ft³ (68 m³) warm for 8 to 12 hr. The operation will vary slightly, depending upon the size of the heater, the size of the room and the amount of heat needed to be comfortable. During the
See Reference 5.