Everyone can name some parts of a chimney system. The hearth, the mantle, the dampers, the flue, the chimney cap – you probably know what part each of these plays in burning a fire in your fireplace. Some parts are lesser known. Take the smoke chamber, for example. Most homeowners wouldn’t know where this is found or what role it plays in having a safe, crackling fire and a smoke-free room. Read on to find out more about this important part of your chimney system.
Purpose of the Smoke Chamber
Even though the name isn’t so well-known, the smoke chamber is a critical part of your chimney system. It is located above the dampers, but below the flue of your chimney, and its purpose is to receive the exhaust gases from the firebox and send them on up into the chimney flue, compressing the gases without creating a backdraft; this will promote good draft and help to avoid a smoke-filled room.
Smoke chambers are present in mortar fireplaces, not factory built fireplaces. The smoke chamber generally has sloped sides and front, but a vertical back. In a well-designed smoke chamber, the sides and front will have the same degree of slope, which will contribute to a good draft. The walls of the smoke chamber should be as smooth as possible, and this is sometimes where the problems starts. In some cases, the smoke chambers were built with a corbelled design, which basically means they were staggered so that the higher bricks stick out further than the lower bricks. This can cause a problem because the uneven pattern can cause resistance as the smoke tries to flow from the firebox to the flue and then out the top of your chimney.
The National Fire Protection Association (NFPA)-211 Code Book (2006) states that “The inner surfaces of the smoke chamber shall be parge coated smooth, with an insulating refractory mortar…” Referring to a corbeled design, the 2006 International Residential Code (IRC) states that “the inside surface shall be parged smooth” (R1001.8). If the walls of your smoke chamber are corbeled, you will need to have them parged.
Parging your smoke chamber refers to the process of applying a coating of mortar to give your smoke chamber walls a smooth finish, which will reduce drag on the smoke released by your fire. There could also be gaps in your smoke chamber that need to be sealed. Parging can take care of that, as well. Bob Fish, a veteran instructor of the National Chimney Sweep Training School, says that when you parge your smoke chamber, you are also adding an insulating layer to it.
Who To Call
If you’re looking to have your smoke chamber repaired, resized, or parged, the place to call is Old Dominion Chimney. Their team of professionals has over twenty years of experience in restoration and resizing of smoke chambers. They offer experience, expertise, and great service not just in smoke chambers but for all of your chimney and fireplace system needs.