Masonry heater

A masonry heater (also called a masonry stove) is a device for warming an interior space through radiant heating, by capturing the heat from periodic burning of fuel (usually wood), and then radiating the heat at a fairly constant temperature for a long period. Masonry heaters covered in tile are called cocklestoves (also tile stoves or ceramic stoves). The technology has existed in different forms, from back into the Neoglacial and Neolithic periods. Archaeological digs have revealed excavations of ancient inhabitants utilizing hot smoke from fires in their subterranean dwellings, to radiate into the living spaces. These early forms have evolved into modern systems. A masonry heater (also called a masonry stove) is a device for warming an interior space through radiant heating, by capturing the heat from periodic burning of fuel (usually wood), and then radiating the heat at a fairly constant temperature for a long period. Masonry heaters covered in tile are called cocklestoves (also tile stoves or ceramic stoves). The technology has existed in different forms, from back into the Neoglacial and Neolithic periods. Archaeological digs have revealed excavations of ancient inhabitants utilizing hot smoke from fires in their subterranean dwellings, to radiate into the living spaces. These early forms have evolved into modern systems. Evidence found from 5,000 B.C. of massive blocks of masonry used to retain heat foreshadowed early forms of fire hearths that were used as multifunctional heating sources. Later evolutions came in the Roman hypocaust and Austro-German cocklestove (Kachelofen, literally 'tile stove', or Steinofen, 'stone stove'), using the smoke and exhaust of a single fire. In Eastern and Northern Europe and North Asia, these cocklestoves evolved in many different forms and names: for example the Russian stove (Russian: Русская печь), the Finnish stove (in Finnish: pystyuuni or kaakeliuuni, 'tile oven') and the Swedish stove (in Swedish: kakelugn, 'tile stove' or 'contra-flow stove') associated with Carl Johan Cronstedt. The Chinese developed the same principle into their Kang bed-stove. The masonry heater has gained renewed domestic popularity recently because of its heating efficiency. A masonry heater is defined by ASTM International as 'a vented heating system of predominantly masonry construction having a mass of at least 800 kg (1760 lbs), excluding the chimney and masonry heater base. In particular, a masonry heater is designed specifically to capture and store a substantial portion of the heat energy from a solid fuel fire in the mass of the masonry heater through internal heat exchange flue channels, enable a charge of solid fuel mixed with an adequate amount of air to burn rapidly and more completely at high temperatures in order to reduce emission of unburned hydrocarbons, and be constructed of sufficient mass and surface area such that under normal operating conditions, the external surface temperature of the masonry heater (except in the region immediately surrounding the fuel loading door(s)), does not exceed 110°C (230°F).' The stove is made of masonry such as brick (firebrick), soapstone, tile, stone, stucco, or a combination of materials, rather than steel or cast iron. It is freestanding, and usually requires special support to bear its weight. It consists of a firebox and heat-exchange channels or partitions that provide additional surface area. These absorb heat from the hot exhaust gases before the gases exit into the chimney. The fire in a masonry heater burns much hotter than in a metal stove. Very hot fires reduce emissions significantly. When not being fired, the connection from the masonry heater to the chimney sometimes has a damper to prevent heat from escaping up the chimney; the heat is then radiated from the masonry.