Catalytic Fireplaces and Combustor
Catalytic fireplaces are wood burning units that contain a device similar to the catalytic converter in a car. These devices are known as catalytic combustors and are also commonly referred to as "cats". These can come as fireplace inserts which are able to be installed into both pre-fabricated and masonry fireplaces.
A catalytic combustor is a honey-comb shaped chamber made from either ceramic or glass. It is coated in a metal catalyst, such as palladium, which is then installed into the firebox near the base of the chimney or flue.
The purpose of this device is to lower the combustion temperature of the smoke and gas emissions thereby causing them to burn up before they even leave the combustor. This, of course, means fewer emissions are released into the atmosphere. It also makes the catalytic fireplace a more fuel efficient unit because it produces more heat for less wood.
Catalytic combustors are available in retrofit kits that enable consumers to convert non-catalytic wood burning units into a money saving, environmentally friendly catalytic fireplace. Unfortunately they are not available for all types of fireplaces and so the owner's manual or manufacturer should be consulted before buying a kit. These devices are generally more efficient in wood stoves but fireplace inserts can increase the wood burning fireplace efficiency by up to 30 percent. Combustors should never be directly exposed to an open flame and so a flame deflector plate should be also be installed.
Catalytic combustors need to reach a temperature of approximately 600 º F in order to operate efficiently. Starting a fire using dry kindling can ensure the fire reaches these temperatures quickly and to monitor the temperature a thermometer or heat sensor can be installed. Adding more wood to the fire may lower the temperature but the owner's manual will normally have instructions on how best to go about doing this without affecting the combustor's operation.
Plastics, colored paper, treated woods or other materials containing chemicals should never be burned in a catalytic fireplace as they will damage the catalytic metal coating. Warranties do not cover damage caused to the combustor due to burning such materials. Always check manufacturer instructions on which wood fuels are recommended.
Catalytic combustors should be regularly checked, as much as three times during the period of use, and should also be regularly maintained. When checking the combustor there are several things to look out for: peeling, thermal cracking, crumbling and mechanical cracking. Peeling can usually be seen in the ceramic or metal catalyst coating. Thermal cracking will appear as random lines in the all area of the combustor and will need to be replaced if this occurs. Crumbling occurs as either as a result of to much exposure to an open flame or being cooled to quickly. Mechanical cracking is damage normally incurred as a result of being dropped or some other direct trauma. In most of the situations described, a combustor will most likely need to be replaced as its efficiency will be affected by the damage.
Creosote, soot and ash can accumulate on the coating and in the cells. Ash and soot can be easily brushed off with a soft bristled brush or vacuum cleaner. Creosote will need to be burned off at a high temperature. Soot will is a likely result of this procedure. Catalytic combustors can also be cleaned by submerging them into a boiling solution of half distilled water (not tap water) and half vinegar. It will need to be rinsed with distilled water afterwards and should be given time to dry before using the fireplace again. A fireplace that was originally equipped with a catalytic combustor should never be used if the combustor has be removed or deactivated.