Back Button

Does an Oil Furnace Need a Chimney Liner?

John Landers

An oil furnace needs a chimney liner. The purpose of any chimney liner, or flue, is to keep the smoke, fumes and toxic gases from penetrating the chimney mortar and entering the living space. The fuel used in an oil furnace creates an oil mist. If this by-product is not correctly vented, the substance will build up on surfaces around the home; the process is called “puff-back.” Cleaning up the mist can be costly. Also, a chimney liner protects the framing and walls of the structure from extreme heat and prevents fire.


Before 1965, chimney liners were not required. So, many older homes have chimneys that had no liner install during the initial construction. Even if a liner was constructed, deterioration from chimney fires, water damage or just plain old age compromises the liner over the years. Chimney liners were made out of terra cotta tiles, which become damaged and allow combustion by-product to seep out of the chimney. The solution is to install a new chimney liner.

When lining the chimney, it is important that the liner is the correct size for the appliance. Find out what the building codes are and read the owner's manual for the chimney specifications. Whether you hire a professional or decide on doing the job yourself, understand and compare the lining warranties.

If you plan to install the liner, speak to your insurance company to find out how the do-it-yourself installation affects your policy. Some insurance companies will refuse any claims connected to projects not installed by a licensed technician.

Approaches to installing a chimney liner for an oil furnace including lining or relining the chimney with clay tiles; installing a pour-in-place liner; or inserting a stainless-steel chimney liner.

Lining Methods

Although clay tiles are inexpensive, relining a chimney with clay tiles is a labor-intensive process. This is the least popular method for relining a chimney for an oil furnace. Poured-in-place and cast-in-place chimney liner relining have gained acceptance as viable alternatives.

The installation process consists of an inflatable tube inserted through the top of the chimney. The form has spacers that separate the form from the walls of the chimney. A semi-liquid mixture is pumped down the chimney. The mixture seeps into openings, cracks and crevices. It also replaces missing mortar and secures loose bricks. The end result is a seamless lining or a new flue. The material cures in 24 hours and the form is removed.

The most common technique for lining a chimney used for an oil furnace is to install a stainless-steel liner. Stainless-steel liners are available in rigid or flexible piping. The lining is available in a variety of sizes. The installation can be handled by most do-it-yourself homeowners. A rope or winch is employed to lower the pipe down the chimney. Sometimes, a combination of flexible and rigid pipes is used to install the liner.