Clean Sweeps of Michigan's Blog

Chimney Terminology: Chimney or Flue or Vent?

Despite its simple appearance, your chimney is much more complicated than it might seem. While chimneys may decorate your roofline, they serve a much more important purpose than for mere aesthetics.

Because there are a variety of different kinds of chimneys, many homeowners do not know the correct chimney terminology to use when describing their fireplace system. Below is a discussion of three of the most commonly confused fireplace terms: chimney, flue, and vent.

Chimney

The chimney is the vertical stack that extends from the top of your roofline, allowing smoke, gas, or other products of combustion to exit your home. A chimney may pass through other parts of the house before exiting your home; this is especially true in homes where the chimney is not on an exterior wall or is on the first floor.

Chimneys are typically constructed of bricks, mortar, or other masonry or are factory built and made of stainless steel. Some factory built chimneys are covered with a decorative chimney chase or siding or other roofing materials to match the rest of the house.

In a discussion of the parts of your fireplace system, the chimney tends to be the exterior portion that is exposed to the elements.

Flue

The term flue refers to the passage by which smoke, gas, or products of combustion are moved to the outdoors. Ducts, pipes, vents, and even chimneys can all be considered types of flues. The purpose of the flue is to protect the rest of the home from the heat of the byproducts of combustion caused by a fire.

Most homes with modern fireplaces have a lined flue. Many flues are lined with tiles, although they may need to be relined over time due to damage or decay. Chimneys with damaged flue liners are often repaired with cast in place or stainless steel liners to ensure the flue has no gaps or holes through with hot air, gas, embers, or sparks could escape.

Vent

Vents are similar to fireplaces and flues in that they may pass through other parts of the house and they do need temperature protection to prevent a transfer of heat from the vent to the surrounding building materials. However, vents are not designed to handle the high heat produced by wood burning fires. Because of this, vents are most commonly used with gas fireplaces.

Vents may exit vertically through the roof, but may also exit horizontally through a wall. Like chimneys and flues, vents allow the byproducts of combustion to exit the home while simultaneously drawing in outside air to fuel the fire. By drawing in air from the outside into a closed combustion system, fireplaces with vents are able to operate much more efficiently than their open hearth counterparts.

If you’re unsure as to whether your fireplace system has a chimney, flue, or vent, contact Clean Sweeps of Michigan today. Our highly trained staff can evaluate the health of your fireplace system while making sure you know the correct terminology to use for the future.

Common Replacements for Chimney Parts

It’s time to fix your chimney up. Start by replacing those parts that have not been working the way they should and those that poses a threat to your family’s safety.

Your chimney system is comprised of numerous parts, all of which are inspected by a chimney professional during your yearly chimney inspection and sweeping. To prevent major chimney system repairs, it is of paramount importance to make minor repairs as soon as problems arise. Some parts are in the line of fire more than others and are adversely affected by the heat, while other parts are exposed to the elements, thereby causing them to wear out faster. Either way, these parts need to be replaced at one point or another. Keep reading to get a better understanding of some of the more common chimney repairs that our technicians encounter.

Help—My Mortar Joints are Crumbling

The mortar used in the construction of your chimney is exposed to the elements on the outside and the heat from your firebox on the inside. This greatly speeds up the weathering process. As such, it is common for it to begin to crumble and fall away, leaving open areas between the bricks, which only exposes even more to these weathering agents. As you might guess, this leads to even more issues. The process for repairing your damaged mortar is known as repointing. During this process, the damaged, old and loose mortar on your chimney is removed from the joints between the bricks and replaced with new mortar or masonry repair caulk. Only a skilled professional should repoint a chimney, as the work requires an experienced hand.

Caps Aren’t just for Baseball

The basic job of a chimney cap is to cover the chimney’s opening in an effort to keep water, birds and other wildlife, leaves, twigs and other debris from getting into your chimney and/or house. Water is directed away from the center and off the sides of your chimney. Birds, other wildlife, leaves, twigs and other debris are blocked from getting to your chimney via the mesh screening on the side, thereby preventing it from becoming a giant trash can. If any of these things were to get into your chimney, they could damage the chimney and cause more problems for you down the road. On the other hand, keeping them all out can increase the lifetime of your chimney liner. Deciding to purchase a chimney cap and have it installed by a professional chimney technician is a choice you won’t soon regret.

Chimney Flashing is Nothing to Overlook

Chimneys are notorious for leaking, and the culprit is almost always the flashing, which lies at the point where the chimney rises above the roof. It keeps water out of the chimney, protecting both the flue and roof. Flashings are made from a variety of materials (e.g., aluminum, copper, galvanized steel, and/or tin). You’ll want to have new chimney flashing installed is it’s missing, rusted through, falling out or completely covered with roofing tar (a common short-term fix that’s sure to be hiding bigger problems). Many homeowners also opt to have new flashing installed when having new shingles put on because they want it to last as long as the new roofing (anywhere from 25-40 years).

Keeping Warm Air in and Cold Air Out

The main purpose of a damper is to seal the chimney airtight when it’s not in use. Heat rises, and if the chimney isn’t sealed when the fireplace isn’t in use, all of the heat in the house goes up the chimney. Liken this to leaving your door open in the middle of winter. You wouldn’t do that, so why settle for a damper that doesn’t seal properly. There are two different types of dampers: top sealing and throat mount. Each type has its pros and cons; in a perfect world, you’d have one of each installed, as this would provide you with the best overall performance. Dampers are one part of your chimney that you shouldn’t leave to function inadequately.

Ushering those Harmful Gases out of your Home

According to the CSIA, problems in your chimney’s flue can present serious risks to your home and family, because it’s no longer able to perform its primary function: to safely contain and vent the products of combustion to the outside of your home. If your current liner was installed improperly or is deteriorating, it is highly recommended that you either have a new one installed by a licensed professional or, if possible, have your current liner repaired. There are several different relining options (clay, stainless steel, and cast-in place liners), depending on both the type of flue liner you currently have and the overall condition of your entire flue. Because of the critical job completed by your chimney liner, it is a critical part. Every chimney needs a working liner.

As you can see, a chimney technician’s job is far more labor intensive that one might think. Chimney systems are comprised of many parts that depend upon one another to function at peak levels. A problem with one part of the system can cause another part of the system to have to work harder to pick up the slack, thereby causing that overworked component to wear out at a much quicker rate. This can become a vicious cycle rather quickly if the initial problem isn’t addressed in a timely manner. The moral of the story: repair minor problems as soon as possible so as to prevent them from becoming major problems down the road.