Santa's Friend Chimney Service Blog

The Different Types of Chimney Liners

A masonry chimney is lined with a ceramic, clay, or metal conduit that contains the products of combustion, directs these outside the home, and protects the walls of the chimney from corrosion and heat. Most fire codes mandate use of a chimney liner due to the safety hazards presented by an unlined chimney. The National Bureau of Standards found that heat moves through an unlined chimney so quickly that adjacent woodwork may catch fire within just 3 ½ hours.

Chimney liners protect homes from heat transferred to combustible materials during fireplace use. Liners also protect chimney masonry from corrosive byproducts of combustion that can reduce chimney life and threaten home occupant safety. The three main types of chimney liners are: metal, clay tiles, and cast-in-place.

Metal liners are made from aluminum or stainless steel and typically used to repair or upgrade an existing chimney. Aluminum is used for a medium efficiency gas system while stainless steel is appropriate for gas, oil, or wood burning systems. High-temperature insulation is installed with this liner to improve performance and safety.

Clay tile is the most common type of chimney liner. It is inexpensive, easy to obtain, and performs well in an open chimney system. However, it does not rapidly absorb or evenly distribute heat during a chimney fire. Unequal expansion may cause flue tiles to crack or split. Clay tiles cannot contain liquid byproducts of combustion from modern gas systems.

A cast-in-place chimney liner is a lightweight, cement-type product. It is castable and installed inside a chimney to provide flue gases with a seamless, insulated passageway. This permanent liner can improve the structural integrity of an aging chimney. Homeowners should have a chimney inspection to determine whether a new metal, clay tile, or cast-in-place liner is required to bring the system into compliance with current fire and safety codes.

Getting Your Chimney Ready for Maintenance

If you have ready any of our posts, you know we recommend that you have your chimney and fireplace professionally cleaned and inspected at least once a year. Doing so ensures that your chimney is safe to operate and that the structure is sound both inside and out. However, before you have a professional chimney sweep come into your home, there are a few things you need to do to make sure your chimney is ready for maintenance.

1. The chimney and fireplace should not be used at least 24 hours prior to any maintenance. This ensures that the fireplace and chimney have properly cooled before the technician performs their tasks.
2. The area around your fireplace may need to be cleaned. By this we mean move your photos and such off the mantle to avoid them getting dirty or broken. While chimney sweeps take the greatest care in protecting all homes they work in, there is no need to invite and accident to happen.
3. Clear out the immediate area around the chimney so the sweep has plenty of space in which to work. If you have chairs or other furniture within about six feet of the fireplace, just move it to the side to allow plenty of space for the technician.
4. Once the chimney sweep arrives in your home, ask them any questions you may have about the process and what they will be doing. You are also encouraged to sit in the background and watch them work. This often serves as an education for the homeowner in that they can learn basic maintenance tasks from the sweep.
5. When the cleaning is done, go over any procedures again with the sweep of which you are unsure. For instance, if you want to know the best way to sweep out the chimney, demonstrate it in front of the sweep to ensure you are following the safest procedures.

What Is a Chimney Damper?

A chimney is actually a complex system comprised of multiple components, one of which is the damper. This metal spring door is located at the top of the chimney or above the fireplace. An attached metal chain runs down the chimney, allowing the user to open and close the chimney from inside the house. When the damper is closed, warm or cool air is kept inside the home, conserving energy use.

Diagram courtesy of the CSIA

If the chimney does not have a damper, at least one-quarter of the energy used in the home is literally going up the chimney. The damper enables the chimney flue to close when the fireplace is not in use. The air generated by a central HVAC system remains inside the home instead of being funneled up the chimney.

A damper also prevents insects, birds, and small animals from entering the chimney. Water and other debris are kept out of the chimney when the damper is closed. If a damper was not included when the fireplace was built, it can be installed later. The best dampers are made from material that will not rust, extending their lifetimes.

Since the damper can only be seen by looking up or down the chimney, many people forget it exists. This causes some to start a fire without first opening the damper. The result is a lot of smoke in the home and no flame in the fireplace. At some point, this is bound to happen but fortunately, opening the damper will remove the smoke.

Spend the money to have a chimney damper installed because it will quickly pay for itself in reduced energy costs. Select a non-rusting damper, not a cheap version made from inferior materials. Have a professional install it and conduct a chimney inspection in the process to verify that the system is not in need of repair.

Top Tidbits You Need To Know About Your Chimney

Whether you are buying your first home with a chimney or perhaps having one installed so you can enjoy a fireplace, there are some basic facts you should know. That new fireplace will add significant ambiance to the home, but there are also some maintenance and safety issues of which you need to be aware.

1. You chimney should be inspected and cleaned at least once a year. This ensures that the chimney is structurally sound and clean, therefore safe to use.
2. When scheduling your chimney cleaning and inspection, only use NCSG certified chimney sweeps.
3. Regardless of how often your chimney and fireplace have been used the prior year, the fireplace and chimney still need a thorough cleaning prior to the new season. Some prefer to have them cleaned in the spring (stating the benefit of having the creosote buildup removed and avoiding any musty odors over a hot summer), while others recommend an early fall cleaning (this will ensure that any birds or debris that may have gotten into the chimney during the spring and summer will be removed before the fireplace and chimney are in use again).
4. Never operate the chimney unless the damper is fully open.
5. Creosote is a substance created by flue gas residue and unburned wood particles. It gathers in the flue with usage of the chimney. As little as 1/8″ is enough to start a fire.
6. Never burn trash or plastics in your chimney. It is meant to burn wood, not become a trash incinerator.
7. A chimney cap can prevent water, debris, and animals from getting into your chimney. If you do not have one installed, consider having this done as soon as possible.
8. Chimney Swifts are protected by the Migratory Bird Treaty. If a swift makes its home in your chimney, it cannot be removed until the birds migrate south for the winter.
9. You should use some type of fireplace screen when your fireplace is in use. This can prevent embers from inadvertently escaping the fireplace as well as prevent children and animals from reaching into the fire.
10. Your chimney has a protective liner inside of it. These lines can be made from a variety of materials, such as stainless steel and clay. The liner should be checked periodically to ensure structural integrity.

Keeping Your Chimney Clean and Safe

It cannot be overstated how important it is to have your chimney regularly cleaned. With all the buildup that comes with the burning of wood, you are bound to have a lot of very flammable creosote caked on the side of your chimney flue. Regular cleaning will help prevent the possibility of a chimney fire. After all, that is the worst possible way to spend your holiday season, and it is completely preventable!

To help cut down on creosote, burning the proper wood is crucial as well. You will want your wood to be hard and to burn hot. Slow and low burns release more creosote, whereas hot fires will burn deposits up through the chimney. Be careful though. You don’t want your wood piled too high in the fireplace. There should be at least 2 inches between the logs and the chimney flue.

It is highly recommended to have your chimney swept if you have vented gas logs as well. Gas leaks could release dangerous amounts of carbon monoxide into your home. As with a wood burning fireplace, any obstructions, like animal nests or leaves, are a potential fire hazard.

That Roof Leak Could Possibly Be a Chimney Leak

Many homeowners see water dripping from their attics or upper story ceilings and immediately assume that the roof is leaking. In some cases, the chimney may actually be the source of the problem. The chimney sits atop the home, where it vents hot air and smoke from the fireplace. It is often neglected until it stops doing its job, which can prevent many homeowners from realizing that there is a problem in the area.

Chimneys may look simple but they feature intricate construction and perform complex tasks. A masonry chimney can suffer at the hands of weather conditions, resulting in loose masonry, an obstructed flue, or a damaged liner. The brick, concrete, mortar, stone, cast iron, steel, and flue tile present in many chimneys are adversely affected when they come in contact with or are penetrated by water.

After prolonged contact with water, most materials that form a masonry chimney will deteriorate. Freezing and thawing can cause masonry materials to erode rapidly because the expanding and freezing process causes undue stress on the materials. Water can also rust cast iron, steel, and other metals used in the chimney, weakening or destroying these components.

When water penetrates the chimney, it can deteriorate the masonry or metal firebox and rot wood adjacent to the fireplace. The chimney exterior and walls and ceilings within the home may develop water stains. Mortar on the chimney exterior can decay and the chimney flue liner may deteriorate or crack. Even the support for the hearth can be affected, resulting in collapse.

Homeowners who suspect a roof leak should contact a professional to ensure that it is not really a chimney leak. Chimney crown, flashing, or mortar joint repair or replacement may solve the problem. Installing a chimney cap can prevent future water penetration and has the added benefit of deterring animals from nesting in the chimney.