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3 Different Types of Chimneys and What Affects the Draft

chimney inspection and chimney sweeps near bon air vaAll chimney types do the same job of channeling combustion gases from solid-fuel fires to the out-of-doors, though several factors determine how efficiently a chimney works. The type of appliance you have primarily determines which type of chimney is required for your home. Although there are many more design options when it comes to chimneys, there are only three basic types of chimneys.

Factors That Affect Chimney Operation

The chimney draft is what chiefly determines whether a chimney is doing its job properly. The factors that commonly affect the draft include flue size, air pressure, chimney height, and chimney obstruction.

The first three of the four are somewhat complex, and some basic information follows:

Flue Size

The flue size is crucial as regards proper operation of a solid fuel heating appliance. An equation can be used to determine the right flue size. In essence, measurements of the fireplace opening width, the opening height and the intersect of those two measurements together with the intersect line measuring height determines flue size in a uniform sizing chart for fireplace and chimney flue installations.

Air Pressure

Many new homes are remarkably airtight. As a result, a chimney will often lack the air it needs for a proper chimney draft. Varying air pressures in a home can cause the “stack effect,” which can negatively affect the draft, as well.

Chimney Height

There is also a formula regarding chimney height, to ensure proper draft. Part of that formula, as an example, is that there should be at least 15 feet from the floor of the fire pit to the top of the chimney.

Chimney Obstruction

Finally, chimney obstruction will affect the draft. A buildup of creosote in the chimney can cause blockage. Animals and debris, such as leaves or deteriorating masonry, can also cause an obstruction that reduces the efficiency of the chimney draft. It’s important to install a chimney cap for various reasons which include preventing blockage by a critter seeking warmth and by debris from outside.

Types of Chimneys

Masonry Chimney

Typically, a masonry chimney is built with a clay tile flue. The flue connects to a fireplace, a heating stove, or a furnace. Brick, stone, and cement blocks are standard materials used for masonry chimneys, which usually last for at least a century. The mortar used between the masonry, however, lasts only about one-quarter that long.

Once mortar begins to deteriorate, usually after 25 years maximum, a procedure known as “tuckpointing” or “repointing” can be used to replace the mortar and restore structural integrity to the chimney. If the mortar fails and allows water into the masonry or if moisture gets into the masonry in any number of other ways, chimney repairs are needed. Without repair of water-damaged masonry, a chimney will begin to lean and could collapse.

Metal Rooftop Chimneyhouse chimney with vinyl siding

Prefabricated fireplaces are common in modern homes and as add-ons in existing homes. The basic level of a prefab chimney includes a metal pipe that runs up past the roofline, releasing gases the same way a masonry chimney does. No flue liner is needed. A specific chimney is made to fit with a coordinating appliance, and following manufacturer’s instructions ensures that the correct chimney is installed. Safe use of your prefab fireplace and metal chimney is best ensured by scheduling professional installation.

Chimney Chase with Metal Chimney

Some metal chimneys are also known as “stick chimneys,” and an additional feature is required for their safe operation. These metal chimneys are surrounded by a chimney chase cover. The chase cover is often made of siding. It can, however, be built with real or faux brick or any other material approved for this purpose. A decorative chimney shroud will completely obscure the metal chimney, which increases the chimney’s aesthetic value.

Contact Chimney Saver Solutions

For chimney installation, chimney inspections, chimney cleaning, and chimney rebuilds, contact the certified experts at Chimney Saver Solutions, the most respected chimney company in the Richmond area. Our chimney sweeps are the best trained around, and we are proud to serve residents throughout the region. We will help to ensure proper chimney operation and can provide chimney maintenance that’s second to none, as well. Call Chimney Saver Solutions today at 804-440-5000 for the best chimney services.


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