Defining a smoke chamber:
An important part of any fireplace is the smoke chamber. For instance, it’s the area of the chimney which provides support for the clay flue tiles that make up the chimney’s liner.
According to NFPA 211, the walls of smoke chambers should be 6″ thick if lined with firebrick or 8″ thick. If no firebrick is present and the inside surface of it which should be smooth.
Another problem is an oversized chamber and in which creates problems as well. They are too large for the firebox which often causes a fireplace to smoke excessively. This is until the fire gets hot and a good draft is established. Hence, this makes it harder for a sweep to access and clean.
Uneven inner surfaces cause the smoke to move in a circular motion over each of the uneven parts which decrease the chimney’s performance and may even cause issues like smoking problems.
This is important to note it is the heat, not flame and in which it is needed to ignite combustibles. If there is not sufficient clearance between the smoke chamber and combustibles, or any part of the chimney flue system and combustibles for that matter, if the chimney flue system gets too hot combustibles near the chimney can ignite.
NFPA 211 states that the height of the smoke chamber should not be greater than the inside width of the fireplace’s front opening and that the depth of it should be less than the depth of the firebox. Keeping these codes in mind, some fireboxes are not as they should be.
In conclusion, if you still have questions about smoke chambers, check out our Ask the Chimney Blogs!
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