The Causes of Chimney Problems

Each year thousands of modern gas appliances are vented into outdated masonry chimneys, resulting in poor draft, excessive water vapor and corrosion. The chimney maintenance industry considers these problems serious because their effects do not show up immediately and the homeowner may not be aware that they exist.

In cold, oversized masonry chimneys, the low temperature exhaust gases of modern appliances rapidly expand and cool. DRAFT, which depends on the buoyancy of these gases, is drastically reduced. If the flue gases stay in your chimney longer, the danger of them leaking into the home increases.

WATER VAPOR is a normal by-product of combustion with any fuel. It condenses on the cool inside surfaces of masonry chimneys, especially those on exterior walls. The resulting water is absorbed by the chimney and transferred through the walls, causing paint to peel and wall-paper and plaster to fail.

Nitric and Hydrochloric acids are often in the condensed water. (This is true when any chlorides enter the combustion process through household cleaners, bleaches, etc. Often the furnace area is right by the washer dryer area and the air is loaded with chlorides.)

In winter, wet chimneys experience numerous freeze and thaw cycles causing eroded mortar joints, cracked and spalled bricks, blocks and clay tile liners. Open mortar joints and flues blocked by debris can force carbon monoxide into the home.

CORROSION, usually associated with metals, can also occur in masonry chimneys, especially when they were previously used to vent oil and coal heaters. Chemical compounds, residue of these fuels and air pollution, combine with water to form acids capable of causing considerable damage to masonry materials.

A major industry study* identified indoor air pollution as a significant factor in the production of acidic condensation in modern heating equipment. The chemical compounds responsible for this acidic condensation originate from carpets, household bleach, cleaning solvents, laundry detergents, paint thinner, etc., ...items we all innocently use and store in our homes.

*1985 Gas Research Institute Study

What Other Problems Can Cause Chimney Damage?

Unfortunately, many times chimney problems go undetected or misdiagnosed. An oversized chimney without a liner reduces the performance and efficiency of any heating appliance.

Low chimney temperatures produce excessive acidic condensation on chimney walls, which causes deterioration both inside and out. Often times, costly repairs to a chimney are performed when a properly sized liner would solve the problem.

Water damage to interior walls caused by porous chimney liners.

Deteriorated chimney which caused the flue to be blocked.

Creosote Filled Chimney

Condensation leakage through chimney thimbles and cleanout doors

Damage from condensate
in the chimney

Acidic condensation leakage caused by a cool, oversized chimney

This costly repair will continue to deteriorate unless a properly sized liner is installed.

When burning solid fuel such as wood, dense creosote deposits left in your chimney can ignite quickly. In deteriorated chimneys, flames can escape to living space and spread rapidly throughout the home.

Damaged, blocked or improperly sized chimneys can create deadly toxins such as carbon monoxide. Leaking undetected through the smallest cracks or back drafting into your home, they can cause sickness and in some cases, even death.