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1434 Sag Harbor Turnpike
Sag Harbor, NY, 11963

(631) 725-0636

For fireplaces in the Hamptons, we're the Hamptons' - Long Island's East End - Hearth Specialists! Sag Harbor Fireplace offers quality service for your chimney, fireplace, and wood stove and an outstanding selection of hearth products. The most recognized and trusted name in the hearth industry for the Hamptons, Long Island, New York.

The Necessity Of A Properly Lined Oil Burner Flue

Frequently Asked Questions

The Necessity Of A Properly Lined Oil Burner Flue

Diane Hewett

A chimney sweep should service your furnace flue after each heating season. When he removes the connector pipe and opens the cleanout door, he can find one or more of the following:

  • Small particles of the chimney liner that have fallen to the base of the chimney
  • No chimney lining
  • A cracked or broken flue tile
  • A wet chimney

These are just some of the problems that can cause poor chimney performance. Most of them can be corrected by relining your chimney.

Old Appliances

The long term effects on the clay tile flue liners venting ol fired appliances can be gradual deterioration of the liner due to acidic nature of the chimney residue. This process can occur over many years. The liner walls can soften and flake off material opening holes through the liner walls. If this happens, the flue must be relined.

New Appliances

New high efficiency oil fired appliances require smaller flue sizes than older units. Where an old unit may require an eight inch flue, the replacement unit’s installation instructions may call for a five inch flue. This is a 60% reduction in flue size. Couple that with lower glass temperatures of new units and the flue size becomes much more critical to the proper operation of the present day oil fired appliance.
In cold, oversized masonry chimneys, the less hot flue gases of modern appliances quickly expand and cool even more.

Draft is drastically reduced because it depends upon the buoyancy of the hot flue gases. The cooler the gases become, the slower they move up the flue and the more the draft is reduced. This will reduce an appliance’s efficiency and increase fuel consumption. The longer the flue gasses remain in the flue, the greater the risk of leakage into the home.

Water Vapor, a normal by product of combustion, condenses on the cool internal surfaces of oversized flues. This problem is worse in exterior chimneys and cold climates. The resulting moisture can be absorbed by the chimney and transferred through the walls. It may cause paint to peel, and wallpaper and plaster to fall. In winter, wet chimneys experience numerous freeze/thaw cycles causing bricks and clay tile liners to spall or flake, mortar joints to erode, and water leakage at te bottom of the chimney.

Dangerous Carbon Monoxide gases can be forced into your home through open mortar joints, cracked flue liners and flues blocked by debris.

Deterioration Of The Flue Liner can occur when venting oil fired appliances. Chemical compounds such as sulfur residues from oil chlorides from the laundry area, when combined with water, form a highly aggressive acids, capable of causing considerable damage to flue tiles in masonry chimneys.

How Can These Problems Be Solved? 

Retrofitting a chimney with a UL Listed, properly sized and properly installed chimney lining system is the most important and easiest way to prevent these problems.


A properly sized chimney lining system will insure correct draft by preventing the flue gases from expanding and cooling more than they should. Properly sizing a chimney liner will greatly reduce condensation within the venting system. The hot and buoyant flue gases will remain hot, exit the flue quicker, cool less and be much less likely to condense on the chimney or liner walls.


By using a watertight flue liner any condensation that might form is contained within the liner, thereby avoiding further damage to the chimney from freeze/thaw cycles and corrosion from the highly acidic condensate. 

A UL Listed stainless steel flue liner or a UL Listed, cast in place chimney lining system designed to vent the flue gases of oil fired appliances should be installed.

A Final Point Concerning Equipment Performance And Efficiency

A new chimney lining system for your oil fired appliance can improve its performance and increase the life of your chimney. Increased oil burner efficiency means less oil is required to heat your home. This reduces your phone bill.