Fireplace - Heating Efficiency

Heating Efficiency

Some fireplace units incorporate a blower which transfers more of the fireplace's heat to the air via convection, resulting in a more evenly heated space and a lower heating load. Fireplace efficiency can also be increased with the use of a fireback, a piece of metal that sits behind the fire and reflects heat back into the room. Firebacks are traditionally made from cast iron, but are also made from stainless steel.

Most older fireplaces have an efficiency rating near zero of less (negative effect that actually cools indoor home temperature) . Standard, modern, wood-burning masonry fireplaces. have an efficiency rating of as high as 15% . To improve efficiency, fireplaces can be modified by inserting special heavy fireboxes designed to burn much cleaner and can reach efficiencies as high as 80 % . These modified fireplaces are often equipped with a large fire window, enabling an efficient heating process in two phases. During the first phase the initial heat is provided through a large glass window while the fire is burning. During this time the structure, built of refractory bricks, absorbs the heat. This heat is then evenly radiated for many hours during the second phase. Masonry fireplaces without a glass fire window only provide heat radiated from its surface. Depending on outside temperatures 1 to 2 daily firings are sufficient to ensure a constant room temperature.