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Installation of a chimney liner

Choose your flue liner kit Installation tipsHow to connect the liner to the stove

flue liner installation

First, you must determine the appropriate size chimney liner for your specific setup. The chimney liner diameter size you will need is the same as the size of the exhaust hole on the appliance. The chimney liner length you will need will equal the height of the chimney. We recommend ordering slightly over that amount to give room for error.

The flue liner legally needs to be a minimum of 6" in diameter if you are burning wood. Unless when you instal a DEFRA-approved stove with a 5" flue outlet, in which case you can use a 5" liner.

Never go down in size along the flue road, as the bottleneck will cause smoke to back up.

If you install a chimney liner into an existing chimney, be sure to get the chimney cleaned first, as this will ensure there is no residual soot or other obstructions that could create difficulties with the installation.

Once installed, it is important to remember that when all such work, has not been carried out by a HETAS registered installer, it must be inspected as per the UK Building Regulations Document J. This check ensures that all flue liners are properly installed; that they are the right size for the appliance requirements and that they are completely free of obstructions.

Only a few tools are needed for a successful chimney liner installation. You'll need a utility knife, flat head screw driver, caulk gun, a pair of working gloves, a power drill and safety glasses. A grinder will give you the best cut when cutting off the excess chimney liner. A saw or hacksaw will also work fine.

You can install your chimney liner from either the top or bottom of the brick chimney stack. Whichever way you choose to install the liner, please ensure that you have sufficient clearance around the outside of the liner to ensure the least amount of friction, or the possibility of catching any bricks within the chimney stack, does not occur.

flue liner

Unpack your flexible liner and attach a rope at the lower end (making sure the rope is long enough to reach the bottom of the stack). Ensure the arrows marked on the liner are facing an upward direction (representing the direction of flue gases).

You will need two people to install your liner successfully, one at either end of the chimney stack. The person on the roof should be safely attached! From the top of the roof, start to push the liner, down the stack. The person at the bottom of the stack should hold the string and take up the slack. Work in tandem to feed the liner down the chimney stack, ensuring that you leave enough liner at the bottom to secure your adaptor and enough at the top to secure the top fixings.

Hang liner in potChimney pot with cowl
Attach the liner to the cowl you are going to use. Place the cowl on the pot.

No pot left
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 of top plate is to seal the existing flue from rain, wind and creatures 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.

chimney flue installation

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.

Locate the locking bolts welded on the four sides of the top plate. Centre the top plate on the clay flue and use your flat head screwdriver to secure the top plate to the side of the clay flue. Warning: Make sure not to over tighten the locking bolts. If tightened too much the clay chimney flue could crack.

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 saw or hacksaw will work just fine.

The next step is to secure the rain cap to the top plate. The collar of the top plate will be inserted inside the rain cap.

What if the liner gets stuck?

Try “turning the liner 90 degrees” whilst you and your helper attempt to pull the push as before. This works if the liner has turned one bend and is not set up for the next bend (has bent itself to point the wrong way). Then try 180 degrees. Any “spinning” is a lot easier for a double bend lower down in the chimney than high up though, due to the sheer amount of liner sticking out of the chimney and lying on the roof.

Sometimes you will have to break into the chimney from the inside or outside of the house and help the liner on its way.

Note: All installations are to be carried out in accordance with UK Building Regulations, Document J. The tips on this page are meant to help you to do so, but in no way should be considered as a replacement for the instructions and rules of Document J.