What Are Chimney Liners?
Chimney liners are conduits made of clay, metal or ceramic material that are installed inside chimneys with three main objectives; to contain combustion products, to safely guide them outside and also to protect walls of chimneys against corrosion and heat.
Even though building regulations may differ, installation of chimney liners has been strongly recommended since the beginning of the 21st Century. As a matter of fact, most fire regulations make it mandatory to install flue lining.
Are you aware that in the 1940’s and 1980’s, the United States National Bureau of Standards routinely tested masonry chimneys because of increased concerns about the liners’ safety and performance?
The scientific tests revealed that chimneys with no liners were very unsafe, to the extent that inspectors proposed that building owners who constructed masonry chimneys without liners be treated like criminals.
What Do Chimney Liners Do?
Chimney liners usually serve three primary functions:
1. Prevent The Transfer Of Heat To Combustibles
In the tests carried out by United State’s National Bureau of Standards, unlined chimneys freely allowed heat transfer through chimneys so fast that woodwork in adjacent areas caught fire within 3 minutes.
2. Provide Flue Of Correct Sizes For Maximum Efficiency Of Appliances
Are you aware that modern oil / gas furnaces as well as wooden stoves can only perform well if the chimneys are of correct sizes?
Incorrectly sized liners may cause excessive accumulation of creosote in stoves that burn wood. In stoves that burn gas, incorrect sizes may cause production of dangerous levels of carbon monoxide.
3. Protect Masonry From Caustic Combustion By-Products
According to the tests run by the National Bureau of Standards, a chimney’s usable life significantly reduces if flue gases penetrate into the building’s brick-and-mortar.
High levels of acid found in flue gases can corrode mortar joints. Erosion of the mortar joints allows rapid heat transfer to combustibles located nearby, and leakage of carbon monoxide and other harmful gases into the home’s living areas as well.
Classification / Types
Chimney liners can be broadly classified into three:
1. Clay Tiles
2. Metal Chimney Liners
3. Cast In Place Liners
These are the most popular type of liners. They are not only affordable, but also readily available. Additionally, clay tiles perform exceptionally well when installed in open-plan fireplace chimneys, especially if the chimneys are well maintained.
However, they are incapable of even distribution and rapid absorption of heat when temperature rapidly rises. Rapid increase in temperature usually occurs when chimney fires occur. Consequently, the flue tiles may crack and separate.
Metal Chimney Liners
Metal chimney liners are usually used whenever there’s need to repair and/or upgrade existing chimneys. They’re made of aluminium or stainless steel.
There are several advantages of installing this type of liners. In case of proper installation and maintenance, they provide maximum safety and can also last for up to 70 years.
Stainless steel is ideal for appliances that burn wood, oil or gas as fuel, whereas aluminium is recommended for appliances with medium-efficiency. The only disadvantage is that metal chimney liners are more expensive that those made of clay.
Cast In Place Liners
They are lightweight products that are usually fixed inside chimneys to form passageways for flue gases that are not only smooth, but also insulated and seamless.
The main advantage is the liners’ capacity to boost structural integrity of old chimneys. Additionally, they are suitable for use in masonry chimneys that burn all types of fuel.
Benefits Of Chimney Liners
1. Chimney liners prevent leakage of carbon monoxide and other harmful gases into living spaces.
2. Nearly all homeowners’ insurance providers are always willing to meet the costs of relining chimneys. This is because the liners offer a lot of protection to homeowners.
3. Gas-burning appliances that ventilate through chimneys usually lead to condensation. In the event that a chimney has no liner, the condensation can significantly enhance masonry deterioration. As a result, the condensate may start leaking back into the house.
4. There are homeowners’ insurance policies that limit insurance coverage for particular cases if renovations are conducted with no improvement in the chimneys.
5. If wood is used as fuel, but the chimney contains no liners, condensation can lead to accumulation of creosote and tar. Since the two products are highly flammable, fire accidents can often occur. Chimney liners therefore help to minimize incidences of fire.
6. Installation of liners helps homeowners adhere to strict building and fire safety regulations. Violation of the codes can force homeowners to part with hefty fines and penalties.