Wood burning stoves basics


Wood burning stoves are the most popular, flexible and economical wood heating option. They can be located almost anywhere there is enough space and where a chimney can be properly routed. A perfect installation has it located centrally in the main floor living area of the house and the flue pipe running straight up into the chimney.

As it is defined as a space heater, it is intended to heat a space directly, unlike a central heating furnace, which supplies its heat to the house through a system of ducts. But because modern houses conserve energy more effectively than older houses and need less heat to stay warm, it is now possible to heat an average-size modern home with a single space heater, provided it is located in the main living area.

The heater should be located in the part of the house you want to be the warmest. This is usually the main floor area where kitchen, living and dining rooms are located and where families normally spend most of their time.

A basement is not a good location for effective space heating. Although the heated air from wood burning stoves does tend to rise to higher levels of the house, this movement is normally too slow and limited to provide comfort on the upper floor. Usually, in an effort to keep the main floor living spaces comfortably warm, the basement is overheated. This can render the basement quite uncomfortable, and may even damage the structure of the house if it’s made out of wood.

Correct wood stove sizing is important because a too large one for the heat demand of the space will be operated with slow, smoldering fires much of the time to avoid overheating the room, and an undersized one can be damaged by frequent over-firing to keep up with heat demand.

The bottom and rear of all new wood burning stoves are shielded to prevent overheating of the floor and to permit close clearances to combustible walls. The more shielded one is, the more of its heat is delivered to the room by warm air convection than by direct radiation from the stove surfaces.

The internal design of wood burning stoves has changed entirely in the past 15 years, as the result of the U.S. Environmental Protection Agency regulation established in the 1980s. The EPA’s smoke emission limit for wood burning stoves is 7.5 grams per hour. Today, they all must meet this limit. Combustion technologies have improved over the years, and now some newer space heaters have certified emissions in the 1 to 4 g/h range. The two general approaches to meeting the EPA smoke emission limits are catalytic and non-catalytic combustion. Both approaches have proved effective, but there are performance differences. In catalytic combustion the smoky exhaust is passed through a coated ceramic honeycomb inside the stove where the smoke gases and particles ignite and burn. Non-catalytic ones do not use a catalyst, but have three internal characteristics that create a good environment for complete combustion. These are firebox insulation, a large baffle to produce a longer, hotter gas flow path and pre-heated combustion air introduced through small holes above the fuel in the firebox.

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