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How to Install a Flexible Chimney Liner

Guide for installing chimney liners with a tee connection

This guide is to give you step by step instructions to install a chimney liner that utilizes a tee connection. These are normally used with appliances that are sitting outside of the chimney and have a thimble connection through the chimney wall.

A chimney liner should be installed anytime an appliance is venting through a chimney. This will reduce the risks of carbon monoxide leaking, creosote buildup, and chimney fire.

You will find stainless steel chimney liners available in 304 and 316 stainless steel. The 304 liners are for wood and pellet burning only and the 316 is an all fuels liner. Make sure you choose the appropriate liner for your needs.

Properly sized chimney liners also improve the efficiency of your appliance and make fireplace maintenance easier.

The chimney liner diameter needed is determined by the exhaust outlet size of the appliance it will be used with. You should always run the liner the full height of the chimney (we recommend ordering slightly more than is measured).

Forever Flex Stainless Chimney Liner Kit

Step 1: Cleaning the chimney

Prior to installing a chimney liner always have it professionally cleaned to remove any creosote or other contaminants. We recommend using only nationally certified chimney sweeps. You can find a certified chimney sweep by going to the following link and entering your information: .

Step 2: Installation tools you will need

You only need a few tools for a successful chimney liner installation. You'll need a razor knife, flat head screw driver, caulk gun, a pair of working gloves, and safety glasses. Shown in the picture is a grinder with a cut off wheel. The grinder will give you the best cut when cutting off the excess chimney liner. A sawzall or hacksaw will also work fine. A power drill will also be needed for the project but is not shown in the picture.

Make sure you wear safety glasses and work gloves to protect yourself from harm.

Step 3: Your chimney liner kit

Every basic chimney liner kit is going to come with four main components: the stainless steel chimney liner, a two part tee, top plate, and rain cap. This demonstration will show a basic installation, but a chimney liner kit can be customized to fit any particular chimney. The top plate is going to be the main variable for a chimney liner kit. For this application, a no sag/no leak top plate is going to be used.

Step 4: Prepare the chimney liner

The chimney liner will be rolled and needs to be straightened. Simply remove any wrapping or ties from the liner and lay it out on the ground to pull it straight.

forever flex chimney liner

Step 5: Insulating the chimney liner

To maintain UL Listing and most manufacturer's warranties for the chimney liner when wood, coal, or pellets are used with the appliance 1/2" of insulation wrap is required. When using home heating oil, natural or propane gas insulation is not required but we do recommend using it as it will reduce condensation.

Simply follow the installation instructions included with the insulation kit or you can purchase the Forever Flex Pre-insulated chimney liner as shown here.

Chimney Liner Insulation Kit          Pre-Insulated Forever Flex Chimney Liner

Step 6: The Tee Connection

You will be using a two part tee. The part of the tee connection with the cut out on the side is known as the tee body or vertical part of the tee. The part of the tee with the looping hose clamp is known as the tee snout or horizontal part of the tee. Start by locating the vertical part of the tee and insert the liner into the top of the female end. Tighten the clamp at the top of the vertical part of the tee around the liner with your flat head screw driver. This will give you a great, tight fit without having to drill screws through the liner.

Place the horizontal part of the tee to the side as you will be using it later.

Chimney Liner Tee Connection   Chimney Liner Tee Connection

Step 7: Insert the chimney liner down the flue

The first part of the chimney liner that will be going down the chimney is the vertical part of the tee connection attached to the liner. Proceed to lower the liner down the chimney until you reach the thimble. The thimble is referred to as the hole on the side of the chimney in the living space that allows stove pipe to attach to the chimney. Twisting the flexible liner will help you install the liner if you are getting caught or hung up on the chimney walls.

You should have someone located by the thimble in the living space ready to install the horizontal part of the tee.

Chimney Liner Install

Step 8: Installing the horizontal part of the tee

Locate the horizontal part of the tee connection. First, insert the horizontal section of the tee, hose clamp end first, into the thimble. Snake the vertical part of the tee through the horizontal hose clamp until the lips of the tee body are inside the horizontal part.

You will find when you look through the inside of the horizontal part of the tee that there is a worm screw. With your flat head screw driver, tighten the worm screw until the two parts of the tee connect. Take this step slowly. As stated above, the lips of the vertical part of the tee should be inside of the horizontal part.

Step 9: Connect the stove pipe to the tee

Once the tee connection has been installed correctly, it is time to connect the stove pipe to the stove. Most stove pipe comes with three screws per connection point. Use your drill and drive the screws into the horizontal part of the tee and through the exhaust collar of the stove.

Step 10: Installing the top plate for the chimney liner

Once the chimney liner is all the way down the flue to the point of the thimble, the next step is to connect the top plate to the top of the chimney. The main function for a top plate is to seal the existing flue from rain, wind and critters from entering the chimney. It also has a clamp located on the inside collar of the top plate to support the weight of the liner.

Start by using your caulk gun and a tube of weather resistant silicone to run a bead of silicone along the top edge of the clay flue.

Next, thread the chimney liner through the round collar of the top plate so that the top plate is sitting on the top edge of the clay flue.

Center the top plate on the clay flue and seat it firmly in the silicone that has been run along the top of the clay flue tile.

Chimney Liner Install  Chimney Liner Install Top plate

Step 11: Remove any excess chimney liner

When you have successfully installed the top plate, the next step is to cut the excess liner flush with the top of the collar of the top plate. Shown in the picture is a grinder with a cut off wheel. The grinder will give the best cut, but a sawzall or hacksaw will work just fine.

Chimney Liner Install

Step 12: Connect the liner and top plate

Once you have cut the excess chimney liner, the next step is to connect the liner to the top plate. The top plate is meant to bear the weight of the chimney liner inside the flue. On the inside collar of the top plate is a hose clamp. On the outside of the collar is a worm screw that will tighten the hose clamp. Once the liner is flush with the top of the collar of the top plate, take your flat head screw driver and tighten the worm screw so that the hose clamp tightens around the liner.

Chimney Liner Top Plate Install

Step 13: Install the chimney rain cap

The next step is to secure the rain cap to the top plate. The collar of the top plate will get inserted inside of the rain cap. There is a suspended hose clamp at the bottom of the chimney rain cap. See the bubbled-out flange on the collar of the top plate? The chimney rain cap will bottom out on this bubbled flange. The clamp will be suspended just below the bubble to ensure a secure fit. Tighten the rain cap clamp with your flat head screw driver.

Chimney Liner Rain Cap InstallChimney Liner Rain Cap



Congratulations, you have successfully installed a stainless steel, flexible chimney liner!