The Best Chimney for Wood Stoves

General Requirements

• Chimneys should be at least 14 feet high to provide adequate draft. They should extend a minimum of three feet above a flat roof and at least two feet above a roof ridge. The flue should be 25 percent bigger than the size of the stove pipe connecting the stove to the chimney, in order to provide enough room to carry smoke outside and create a draft. Your wood stove should never share a chimney with a fireplace.

Masonry

• Masonry chimneys are made from brick, block or stone. Many homeowners prefer them because of their beautiful appearance, but if you’re using an old masonry chimney, you need to have it inspected to make sure it’s safe. The National Fire Protection code says masonry chimneys should have a fireclay flue liner that’s five-eighths inch thick. In addition, the chimney walls should be at least 4 inches thick and there should be a cap to keep out moisture and animals. If your chimney doesn’t pass inspection, you may be able to reline it with a flexible stainless steel liner.

Insulated

• Double-walled chimneys have an inner and outer layer of metal and are filled with one or more inches of non-combustible insulation. Triple-walled chimneys are a combination of air and insulating material. Several types are made for wood stoves, but they all have to have the Underwriters Laboratory (UL) listed label and state that they’re “all fuel” chimney units. According to the University of Missouri Extension, tests done by the National Bureau of Standards show that prefabricated chimneys, which include double-walled and triple-walled insulated chimneys, perform the same as masonry chimneys when used in the same way. Solid pack chimneys perform better than other insulated chimneys because they contain more insulating material.

Thermo-syphon

• Air cooled thermo-syphon chimneys, which are also known as double-walled or triple-walled air-cooled chimneys, are meant to be used with certain fireplaces. These chimneys use air from the house as insulation between the inner and outer pipes. Because the temperatures are cooler on the innermost lining, creosote builds up faster on this type of chimney and it should never be used with a wood stove.