Flexible Chimney Liners Explained

When chimneys get old or are not maintained properly they can deteriorate and create hazardous conditions. Cracked tiles and deteriorating masonry can allow hazardous gases or even fire to enter your house. In order to remedy these situations there are two things that can be done. The entire existing chimney can be torn down and rebuilt, or you can reline your chimney with a stainless steel or aluminum insert. To tear down and rebuild a chimney is not a small job. It's very labor intensive and can cost quite a bit of money. Sometimes it can be next to impossible, for example if the chimney runs up through the center of the house. The easiest and most cost effective way to repair a chimney is to reline it with a metal chimney liner.

Many chimneys have jogs or offsets as they rise to the top of a structure, so a rigid pipe is not always the best solution. In the event of the absense of a straight chimney a flexible chimney liner can be used. A flexible chimney liner can come in two forms. The first is a heavy flexible liner commonly made of 316L stainless steel. Its exactly what its name implies- heavy. The second type is a light flexible stainless steel liner, this is the most common. Most light weight flexible liners are made of 316ti stainless steel. Aluminum liners are also common for low efficient gas appliances.

Are you wondering what the "ti" stands for in 316ti? The answer, titanium. It ads a bit more protection against high heat and corrosion. It's not neccessary but it doesn't hurt to have it. The flexible liners are built to withstand extremely high heat, in case of a chimney fire. They are said to last a lifetime, but they haven't been around long enough to prove it. However they have gone through extensive testing at Underwriter Laboratories and other testing agencies and have passed.

What's involved in a chimney relining job?
Installation begins with clearing any obstructions that may be inside the chimney. A probe is pulled up the chimney to make sure the chimney is clear. A thorough cleaning of the chimney is not necessary because the new liner will provide a brand new flue for the chimney. It's best to install the widest liner possible to get the best draft possible.

Some chimney liners are installed by pulling them up from the bottom with a winch that is attached to the top of the chimney. It's also possible to pull the liner down the chimney. It all depends upon each unique situation, and many installers have different preferences. Sometimes the liner may need a little coaxing to get it all the way through the chimney, but its flexible nature allows for quite a bit of contorting.

Once installed the liner should be insulated. This is a step that is often avoided, but is a good idea. An insulated chimney liner will allow for the liner to get heated properly allowing for a better draft. There are two types of common insulating methods. The first is a vermiculite and concrete mixture that is poured down the chimney and dries in place. The other is a ceramic wool blanket. This requires more clearance and can result in having to use a smaller diameter pipe which can affect the quality of the draft.

In order to insulate with a ceramic wool blanket you must wrap the liner before it is inserted into the chimney. You start by laying out the insulation on a flat surface. Then the stainless liner is placed in the center of the insulation. The insulation is then wrapped around the liner held in place with a adhesive spray. (this step is optional) A wire mesh is then covered over the liner and insulation to help protect the insulation as its snaked down the chimney. A stainless wire is then spiraled around the mesh just to add a little more strength. The mesh is then held in place on both ends by large hose clamps.

Are all Chimney Liners the same?
Most flexible stainless steel liners are the same from manufacturer to manufacturer. They may vary slightly in their steel makeup, some leaving out the Titanium. They are are very closely related in their design. Some manufacturers make the "hills and valleys" of the liner a little steeper claiming greater flexibility and strength.

Most people are impressed with the strength of the leading manufacturer's liner. Does the liner need to be to withstand the weight of a 300lb man? No, it doesn't. When the liner is placed in your chimney there is no weight pushing on it's sides. So this is something that is not really neccessary, however, it may give people some added peace of mind.

Different companies provide different components with their liner kits. Some have clamps, some use screws, and some use a combination of clamps and screws. Transcontinental Equipment manufactures components that use a patented tab and clip system. The liner kit is very easy to install and can accomodate tight bottom termination areas. The liner is identical to other leading manufacturers. For more information about liner brands click here.

A job only for the pros?
This is a job that is recommended to be done only by pros. However, it is possible for a do-it-yourselfer to tackle the job. If you do decide to do it yourself, make sure to do your research and then carefully select the products you need in order to complete the job.

Reference
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