Flexible Chimney Liners Explained - Stainless Steel Flex Flue Liner Info

Typical Chimneys

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 chimney liner.

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 stainless steel chimney liner.

Many chimneys have jogs or offsets as they rise to the top of a structure, and some do not. In either case a flexible chimney liner may be the best solution. A flexible chimney liner can come in different forms. The first is a 316Ti flexible liner and is the most common. Other options include AL294C for high efficiency appliances (83% and up), and Smooth Wall 316Ti liner. Rigid liner is also available: 304L liner for wood and wood pellets, and Rigid 316L. For most applications the Flexible 316Ti is the most economical and comes with a lifetime warranty for both solid and liquid burning appliances.

Are you wondering what the "Ti" stands for in 316Ti?

The answer is titanium. It adds a bit more protection against high heat and corrosion. It's another improvement to the older 316L and costs about the same. The flexible liners are built to withstand extremely high heat, in case of a chimney fire. They last a lifetime, they have gone through extensive testing at Underwriter Laboratories and other testing agencies and have passed UL1777 and ULC in Canada.

What does the "AL" stand for in AL29-4C?

The AL in AL294C stands for Allegheny Ludlum, the company that designed this special alloy. AL29-4C chimney liners resist corrosion from acids in the flue exhaust produced by high efficiency appliances.

What's involved in a chimney relining job?

Installation begins with clearing any obstructions that may be inside the chimney. A test tube, pulling cone or short piece of liner is pulled up or down 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 fit the liner to the appliance rather than fitting the existing flue to the appliance. The only exception would be if the chimney was being relined for a pre-existing masonry fireplace with no appliance i.e. NO wood stove, insert, new furnace, etc.

The liner should be insulated. This is a step that is often avoided, but should not be. An insulated chimney liner will allow for the liner to get heated properly allowing for a better 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 wrapped around the liner and held in place with a adhesive spray (this step is optional). A wire mesh is then clamped at one end of the liner and insulation and pulled to the other end and clamped there as well. This will help protect the insulation as it is snaked down the chimney. 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.

Are all chimney liners the same?

No, be sure the liner you purchase is 316Ti if flexible, and UL rated. If rigid is used be sure it is 304L for wood and wood pellets and 316L for any type of fuel. If your appliance has an efficiency of 83 percent or higher you should consider the AL29-4C flexible chimney liner. Do not be mislead by low price, usually this indicates made in China. They vary in their steel makeup, some leaving out the Titanium and some leaving out the AL for high efficiency appliances. Most people are impressed with the strength of Forever Flex liner and Rock-Flex Lining systems.

Does the liner need 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 its sides. So this is something that is not really necessary, and is more marketing than anything else.

How are the parts of the chimney liner kit connected?

Different companies provide different components with their liner kits. Some have clamps, some use screws, and some use a combination of clamps and screws. Rockford Chimney Supply only uses components that use a patented quick connect system which requires no screws or rivets. The liner kit is very easy to install and can accommodate tight bottom termination areas.

A job only for the pros?

No, this is a job that is recommended to be done by anyone who is handy, detailed, wanting to save big dollars, and willing to spend a short afternoon doing it the right way as detailed in the instructions provided with the kit. A do-it-yourselfer can tackle the job, and Rockford is available for support 7 days a week.

Rockford Chimney supply stocks a complete selection of chimney liners, chimney parts, chimney flue liners, and more.

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Our 316Ti flexible chimney liner and chimney liner components have passed the rigorous testing at the Underwriters Laboratories with best in class status and are UL Listed. So if you are looking for UL listed chimney liner sold directly to homeowners, then look no further than Rockford Chimney

Customer Testimonials

Back in July you gave me excellent advice re. sizing/purchasing a flue liner for the chimney associated with my wood stove. I'd like to thank you once agai... More

—AE Northfield, MN

A few weeks ago I ordered a chimney liner system for my fireplace insert. Your salesman recommended the liner system plus the insulating blanket. I just wa... More

—AH Happy customer

Just got around to installing my new smooth flexible liner and deluxe terra cotta cap (wow). The quality of your product is second to none. Very pleased an... More

—B.B. from Massachusetts

Thanks so much for the great tech service from Dennis, very knowledgable, friendly and proffessional.Your website is the best, beats your competition by fa... More

—Bill in Knoxville

Sue and Dennis, I received the final part of my order yesterday (the chimney cap that actually fits over the chimney chase). It looks wonderfu... More


Hello, I was shopping for an fireplace insert and called RCS to ask why they were so much cheaper than my local guy, the reply was " we sell thousand of th... More

—Chris, PA.