How to Fit a Chimney Liner

Start by measuring the length of your chimney from the top (where the liner will be installed) to the point where your fireplace or appliance connects to the chimney. This length determines how long your chimney liner needs to be. To do this, use a long measuring tape or a weighted line that you can drop down the chimney.

The flue allows smoke and gasses to travel up and out of your home. The size of your flue will dictate the diameter or size of the liner you need.

For a round flue, measure the diameter from one side to the other across the broadest part. This straightforward measurement will directly correspond to the diameter of the round liner you need.

If you have a rectangular flue, measure both the width and the length of the flue’s interior.

Keep in mind that stainless steel chimney liners typically come in round and rectangular shapes, but there are also oval options that can fit in spaces where a round liner may not work, such as flue bends.

In addition to measuring the chimney, it’s important to know the venting requirements of your appliance if your chimney connects to a wood stove or furnace. The chimney liner's diameter must match your appliance's vent size to ensure proper airflow.

Check the appliance manufacturer’s recommendations to confirm the appropriate liner size. If your chimney is too large for the appliance, you may need a reducer or adapter to ensure a proper fit.

The chimney cap covers the flue and sits on top of the chimney. It needs to be removed to insert the liner. The steps for removal depend on the type of chimney cap you have. Follow the manufacturer’s instructions or work with a local chimney repair specialist.

Start at the top of the chimney and carefully lower the liner down into the flue. It may be helpful to have a pal assist you.

If your chimney has bends, gently twist and push the liner to help it move through. If you’re struggling, try attaching a pulling cone (a unique tool that helps guide the liner) and use a rope to pull it down.

Once the liner is in place, secure it at the top with the top plate in your liner kit using a drill and the appropriate masonry bit. Then, using your caulk gun, apply a generous bead of high-temperature sealant around the edges of the top plate where it meets the chimney to prevent water from seeping into the chimney. Afterward, reattach the chimney cap. Then, apply more sealant.

With the liner secured at the top, it’s time to connect the bottom end to your fireplace, wood stove, or furnace.

Start by guiding the liner down to the appliance’s flue collar, where it will attach to the fireplace, stove, or furnace. You may need to trim the liner to fit, depending on your setup. Use your metal snips to carefully cut the liner to the correct length, ensuring it fits snugly without any excess that could cause kinks or blockages.

Next, secure the liner to the appliance using the appropriate connector. It could be a clamp, adapter, or collar that came with your purchased kit or the appliance.

Tighten the connection to ensure no gaps where exhaust gasses could escape, then add the sealant. Finally, double-check that everything is secure and properly aligned. A tight, secure connection will help maintain a strong draft, prevent leaks, and ensure your chimney system operates safely and efficiently.