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The Anatomy of Your Masonry Chimney

Can you identify the major components of your masonry chimney? If you cannot, you are not alone. Many homeowners have very little knowledge about their fireplace and chimney systems. When you do not know the names of certain parts or what exactly each part is supposed to do, it can be difficult to describe a chimney problem you could be experiencing. Knowing the details of each component of the anatomy of your chimney can help you discuss your issue with chimney professionals, like our staff at Weststar Chimney Sweeps. As part of our responsibilities as Chimney Safety Institute of America (CSIA)-certified chimney sweeps, educating our customers about the major parts of their fireplace and chimney systems is one of our top priorities. We would like to explain each component of the anatomy of a masonry chimney to help you be able to identify these parts and their specific functions.

Masonry Chimney Anatomy - San Diego CA - Weststar Chimney

As identified by the CSIA, the anatomy of a masonry fireplace and chimney system consists of the following parts:

  • Mortar Crown – Also commonly known as a chimney crown, this component is located on top of the chimney to prevent water penetration of the bricks and mortar as well as to stop water leaking down the flue and into your home.
  • Flue – Found in different shapes and sizes, the flue is the chamber that vents out the corrosive byproducts of combustion from the fireplace. A single chimney can have multiple flues if several fireplaces or stoves are connected to the same chimney. Your flue should always be clear from blockages to allow proper airflow.
  • Smoke Chamber – Located above the firebox and below the flue, the smoke chamber allows smoke to mix and rise up the flue. Commonly constructed from terracotta tiles, this part is also known as the chimney throat.
  • Smoke Shelf – Functioning with the smoke chamber to push smoke out the flue, the smoke shelf can be found behind the damper and is at the bottom of the chimney.
  • Damper – Typically located in the same area as the smoke chamber and smoke shelf, the damper seals your chimney closed when the fireplace is not in use. A very important part of the efficiency of your chimney, the damper needs to function properly to keep heated air from escaping out the chimney when there is no fire.
  • Lintel – The heavy piece of angle iron that holds up the bricks over the center of the fireplace, the lintel can be found embedded into the brick.
  • Firebox – A crucial part of your fireplace and chimney system, the firebox is a two- or three-walled structure that contains the direct heat of the fire and guides the smoke into the smoke chamber. As the firebox is exposed to such high temperatures, this component tends to deteriorate faster than other parts of the anatomy of your chimney. It is crucial that the firebox is constructed with the right materials and kept in good repair.
  • Ash Dump – Located right below the center of the firebox, the ash dump is equipped with a door. When the ash dump door is open, ashes from the fire fall into the ash dump. This component allows for simple ash removal from the firebox.

If you have any questions about any of these parts, get in touch with Weststar Chimney Sweeps. We are happy to tell you more about the anatomy of your masonry chimney.

Chimney Throwdown: Throat Dampers Vs. Top-Mount Dampers

Essential for the proper venting of smoke and other byproducts of combustion out of your home, a damper is one of the most important components of your chimney and venting system. Just as an opened window, a opened damper allows air to flow out through the chimney. When the damper is closed, it keeps warm air inside the fireplace and your house. For safety reasons, you should always be sure that your damper is opened when you have a fire burning, but when your fireplace is not in use, your damper should be closed to keep warm air out and cool air in your house during the summer and cold air out and hot air in your home during the winter. If your damper is old and worn out, it should be repaired or replaced as soon as possible to keep your home energy-efficient. To help you decide which type of damper would be best for your chimney, Weststar Chimney Sweeps would like to tell you more about the two different types of dampers and how we can assist you when it is time for a new damper in your chimney.

Chimney System Diagram - San Diego CA

Throat Dampers

Found at the bottom of your chimney (or also known as the throat of your chimney) directly above your firebox, throat dampers are generally found in old masonry chimneys. Constructed from cast-iron, steel, or stainless steel, a throat damper rests on tracks directly above your fireplace. You operate this type of damper by moving a handle on the damper along its tracks to open and close it manually. Some prefabricated chimneys also have throat dampers; however, these steel dampers are often shaped as a square or circle and are opened and closed with a pull-down handle or a left-to-right lever and do not use tracks. You can also find newer throat dampers, which are inflatable devices that seal off the flue to any extraneous air that comes down the chimney, according to eHow. To ensure you have the best sealant, you should get the correct size for your inner chimney walls. Some disadvantages to this type of damper are they can be easily punctured, are not the most energy-efficient, and do not protect your chimney from birds and animals nesting inside your chimney.

Top-Mount Dampers

When you have an old throat damper that is beyond repairing, Weststar Chimney Sweeps will recommend that you install a top-mount damper, which sits on top of your chimney and can also serve as a chimney cap. Very energy-efficient, a top-mount damper is equipped with a silicone rubber gasket to provide an air-tight seal. Constructed from iron or steel, a top-mount damper functions well as a chimney cap when closed. This type of damper will protect your inner chimney from water leaks, debris, and bird and animal invasions. Although the main disadvantage of a top-mount damper is that it is more expensive than a throat damper, you will end up saving money on your heating and cooling bills as well as on costly repairs to your chimney caused by water leaks or nesting animals. Easy to operate, a stainless steel cable runs down your chimney to the firebox, and you simply pull on the cable to both open and close the damper.

Want to know more about these two different types of dampers? Contact Weststar Chimney Sweeps to let our staff help you decide which damper is right for your chimney.