Furnace Safety Information

The incomplete by-product of the combustion of fuel oil is unburned carbon & sulfur – called oil soot. Oil soot accumulates on the walls and at the base of the chimney, which should be inspected and cleaned annually by a CSIA Certified Chimney Sweep™.
The best time of the year to clean an oil chimney is in the spring time, after the heating season. During the winter, the oil furnace is subjected to long running cycles which will produce oil soot that may adhere to the sides of the chimney. The accumulation of these soot deposits will fall to the base of a masonry chimney, or directly into the top of the oil furnace if a metal chimney is located directly above the appliance. It will restrict the flow of flue gases which consist mostly of nitrogen, carbon dioxide, and water vapor. Combustion will also produce carbon monoxide (which is a dangerous gas when not vented properly) which will spill back into the house instead of going up the chimney when the chimney base is not properly cleaned.
A big misconception on many homeowners’ part is that the oil service company takes care of the chimney. The oil burner company may shovel out the base of a brick chimney and brush out the connector pipes, but they will not clean the chimney. Many oil furnaces service men tell the homeowner that the chimney is OK without even inspecting the entire chimney, which includes going to the roof and inspecting the interior as well as the exterior masonry (if applicable), flashing, chimney cap, etc.

The National Fire Protection Assoc. 211 codes state that “chimneys must be inspected and cleaned if needed annually” – just like the oil service man services the furnace annually, so should the chimney system be serviced annually.

Many homeowners also may not be aware that the chimney’s interior, when not maintained, will decay and break down – just like neglecting your teeth and not having them checked annually may result in cavities. (Or if you don’t change the motor oil in your car for 50,000 miles, you can be sure something in the motor will break.) It’s the same thing with your chimney. As stated earlier, the incomplete by-product of combustion is soot, which contains carbon and sulfur. Sulfur, when mixed with rainwater (from a missing rain cap) or moisture from the flue gases themselves is absorbed into the flue tile and starts a deteriorating process called flaking or spalling. Just like tartar on your teeth, annual brushing will remove these soot deposits and keep the deterioration process to a minimum.

In metal chimneys, the interior lining is made from stainless steel, which will not rust but will corrode from the oil soot’s sulfuric acid reaction. This corrosion makes small pinholes which will ruin the integrity of the liner, which will not be able to hold the by-products of combustion. When a clay lining in a masonry chimney flakes or a metal chimney’s insides corrode, they are unable to contain the heat and the flue gases, thus creating a fire and health hazard.

Annual inspection and cleaning by a CSIA Certified Chimney Sweep will find these problems and give you recommended corrective actions. When the sweep arrives at your home to do the annual inspection and cleaning of the oil chimney, he will set up his equipment (vacuum, etc.), remove and inspect the connector pipes (the pipes from the oil furnace to the chimney) – careful as not to spill soot into the home. The chimney connector will be cleaned and closed off so that when the chimney is swept, no soot will enter the home. An inspection of the exterior chimney will be made, the chimney swept, and then the interior of the chimney inspected for deterioration and soundness. The sweep completes the exterior work and next returns inside and removes the soot that was brushed down the chimney. When the connector pipes are re-installed, the furnace will be restarted and checked for proper chimney draft.

Relining Your Oil-Fired Appliance Chimney

The oil burner technician is at your home doing his annual servicing of your oil-fired appliance and when he removes the connectors piping, he notices one of the following conditions:

  • Small particles at the chimney base, a condition known as chimney liner flaking.
  • There is no chimney lining, causing poor draft conditions.
  • The cracked fire clay flue tile at the base of the chimney.

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

But why do these problems occur?

In cold, oversized masonry chimneys, the low-temperature exhaust gases of modern appliances quickly expand and cool.

  • Draft, which depends upon the buoyancy of the gases, is drastically reduced. This will greatly 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 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 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 and thaw cycles causing bricks and clay tile liners to spall (flake) and crack, mortar joints to erode, and water leakage at the chimney base. Open mortar joints and flues blocked by debris can force dangerous carbon monoxide gas into your home.
  • Corrosion of the flue liner can occur when venting oil-fired appliances. Chemical compounds, residues sulfur, and air pollution combined with water to form a highly aggressive acid capable of causing considerable damage to flue tiles in masonry chimneys.

How can we solve theses problems?

Fitting a chimney with a properly sized and installed chimney lining system is the most important way to prevent these problems. It will insure a good draft by preventing the flue gases from expanding and cooling. The warm, buoyant flue gases will exit the flue faster and have less time to leak into the home or condense on the chimney walls or liner. Water vapor contained in the flue gases can’t be eliminated but it can and must be reduced. By properly sizing the liner this goal can be achieved. Any remaining moisture must be contained within a watertight conduit. Keeping any excess moisture in the liner inhibits further damage to the chimney from freeze and thaw cycles and corrosion. The liner should also be resistant to these corrosive acids. A cast-in-place liner or a UL Listed stainless steel chimney lining system that will resist the corrosive acids contained in the flue gases should be installed.

Equipment – Performance and Efficiency

A new chimney lining system for your oil-fired appliance will improve its performance. Efficiency will be increased by keeping more available heat within the home rather than sending it up the chimney resulting in substantial savings.

Gas Furnace Chimneys

A properly functioning gas furnace with a well-designed chimney and venting system produces little soot that must be cleaned. However, gas furnace flues, like other operating chimney systems, need an annual inspection for other safety reasons.
Gas burns so efficiently, under proper conditions, that the primary byproducts of combustion are fumes and moisture – both of which are of major concern to the homeowner.

The higher the efficiency rating of the furnace, the more important it is that the chimney and venting system be properly designed and installed. Mixed with the moisture condensation from gas is a high level of chlorides that can rapidly cause the deterioration of a masonry chimney. Newer furnaces mandate installation with an approved chimney liner system when the connection is made to a masonry furnace as these chlorides can cause SPALLING or flaking of the brick or tile liners in the chimney. Eventually, these little flakes not only compromise the thickness of the chimney flue wall, but they also can accumulate and cause a blockage within the chimney. When a blockage occurs, dangerous carbon monoxide fumes can enter your house and threaten your family’s safety.

The gas furnace’s flue should also be checked for bird and animal nests, which can cause blockages that also may prevent the ability of gas exhausts to properly exit the atmosphere.

All furnace flue inspections should be done during the warm months when the furnace is not operating, as the furnace must be turned off during the inspection process.

For the same reasons mentioned above, gas and oil water heater flues need to be inspected annually as well.

Dangers of Carbon Monoxide

Symptoms of exposure include shortness of breath, headache, dizziness, nausea, disorientation, and suddenly feeling sleepy.

The only way to know if your home is being poisoned is by installing a carbon monoxide detector. Install one detector on each floor of your home, and check batteries regularly.



From: chiefchimney.com