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Lucky Duck's Chimney Sweep

Why clean your fireplace?
Why clean your hot air ducts?

- Ways to keep the fire you want...from starting one you don't!
- Proper Maintenance
- Signs that you've had a chimney fire
- What to do if you have a chimney fire!
- Why clean your hot air ducts

Creosote & Chimney
Fires : What You Must Know

Fireplaces and wood stoves are designed to safely contain wood-fueled fires, while providing heat for a home. The chimneys that serve them have the job of expelling the by-products of combustion - the substances given off when wood burns.

As these substances exit the fireplace or wood stove, and flow up into the relatively cooler chimney, condensation occurs. The resulting residue that sticks to the inner walls of the chimney is called creosote. Creosote is black or brown in appearance. It can be crusty and flaky ... tar-like, drippy and sticky ... or shiny and hardened. Often, all forms will occur in one chimney system.

Whatever form it takes, creosote is highly combustible. If it builds up in sufficient quantities - and catches fire inside the chimney flue- the result will be a chimney fire. Although any amount of creosote can burn, sweeps are concerned when creosote builds up in sufficient quantities to sustain a long, hot, destructive chimney fire.

Certain conditions encourage the buildup of creosote, restricted air supply, unseasoned wood and cooler-than-normal chimney temperatures are all factors that can accelerate the buildup of creosote on chimney flue walls.

Air supply : The air supply on fireplaces may be restricted by closed glass doors or by failure to open the damper wide enough to move heated smoke up the chimney rapidly (the longer the smoke's "residence time" in the flue, the more likely is it that creosote will form). A wood stove's air supply can be limited by closing down the stove damper or air inlets too soon and too much, and by improperly using the stovepipe damper to restrict air movement.

Burning unseasoned firewood : Because so much energy is used initially just to drive off the water trapped in the cells of the logs - burning green wood keeps the resulting smoke cooler, as it moves through the system, than if dried, seasoned wood is used.

Cool flue temperatures : In the case of wood stoves, fully-packed loads of wood (that give large cool fires and eight or 10 hour burn times) contribute to creosote buildup. Condensation of the unburned by-products of combustion also occurs more rapidly in an exterior chimney, for example, than in a chimney that runs through the center of a house and exposes only the upper reaches of the flue to the elements. back to top

WAYS TO KEEP THE FIRE YOU WANT... from Starting One You Don't!

Chimney fires don't have to happen. Here are some ways to avoid them :

Use seasoned woods only (dryness is more important than hard wood versus soft wood considerations)

Build smaller, hotter fires that bum more completely and produce less smoke

Never burn cardboard boxes, wrapping paper, trash or Christmas trees; these can spark a chimney fire

Install stovepipe thermometers to help monitor flue temperatures where wood stoves are in use, so you can adjust burning practices as needed

Have the chimney inspected and cleaned on a regular basis
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Proper Maintenance

Clean chimneys don't catch fire. Make sure a Chimney Sweep inspects your solid fuel venting system annually, and cleans and repairs it whenever needed.Your sweep may have other maintenance recommendations depending on how you use your fireplace or stove. back to top

Signs that You've Had a Chimney Fire

 Since chimney fires can occur without anyone being aware of them ... and since damage from such fires can endanger a home and its occupants, how do you tell if you've experienced a chimney fire? Here are the signs a professional chimney sweep looks for: 

"puffy" creosote, with rainbow colored streaks, that has expanded beyond creosote's normal form

warped metal of the damper, metal smoke chamber, connector pipe or factory-built metal chimney

cracked or collapsed flue tiles, or tiles with large chunks missing 

discolored and distorted rain cap

creosote flakes and pieces found on the roof or ground

roofing material damaged from hot creosote

cracks in exterior masonry

evidence of smoke escaping through mortar joints of masonry or tile liners

If you think a chimney fire has occurred, call  your chimney sweep for a professional evaluation. If your suspicions are confirmed, a certified sweep will be able to make recommendations about how to bring the system back into compliance with safety standards. Depending on the situation, you might need a few flue tiles replaced, a relining system installed or an entire chimney rebuilt. Each situation is unique and will dictate its own solution. back to top

 What to Do if You Have a Chimney Fire

 If you realize a chimney fire is occurring, follow these steps:

 1) Get everyone out of the house, including yourself

 2) Call the fire department

If you can do so without risk to yourself, these additional steps may help save your home. Remember, however, that homes are replaceable, but lives are not:

Put a flare type chimney fire extinguisher into the fireplace or wood stove

Close the glass doors on the fireplace

Close the air inlets on the wood stove

Use a garden hose to spray down the roof (not the chimney) so the fire won't spread to the rest of the structure

Monitor the exterior chimney temperature throughout the house for at least 2 or 3 hours after the fire is out

Once it's over, call a Chimney Sweep to inspect for damage. Chimney fire damage and repair normally is covered by homeowner insurance policies. back to top

Air Ducts and Indoor Air Quality
"Why clean your duct work?"


Joe Laquatra

Air ducts, the components of heating, cooling or ventilation systems which distribute air throughout a house, have been a relatively recent focus of research on their potential relationships with indoor air quality. Those studying this issue have noted a tendency of ducts to accumulate a build up of dirt, mold and other materials along their interior surfaces. Early reports indicated that these materials can contribute to particle pollution in the air inside homes. Within a short period of time, an industry has sprung up which offers duct cleaning services. But because the technology is new and the industry is young, questions about the need for and effectiveness of air duct cleaning are being asked.

The presence of dirt and dust in air ducts does not necessarily contribute to indoor air pollution. Small amounts of these materials are normal in ducts, and usually adhere to their interior surfaces and remain there without entering the living space. Large amounts, however, can be a source of pollutants released into the home. If moisture enters ductwork, either from high levels of relative humidity in the home, a leaking humidification system, or any other source, biological contamination can occur. Mold growth in ducts can result in spores being distributed throughout the home, which can cause allergic reactions and other health problems in some people. Insects or rodents in duct work can also cause unhealthy contamination.

If ducts are to be cleaned, because of excessive amounts of dirt and dust, mold growth, or vermin infestation, the causes of these contaminants should be investigated first, and problems should be corrected at their sources. Otherwise, they are likely to return after ducts have been cleaned. Consumers who have ducts cleaned by a professional air duct cleaner should make sure that all components of a system are cleaned, including supply and return ducts and registers, grills, diffusers, heat exchangers, heating and cooling coils, condensate pans, fan motors and housing, and air handling unit housing.

Duct cleaning methods vary, but standards have been established by industry associations. Some duct cleaning professionals use remote optical cameras to inspect duct interiors and specialized tools to dislodge debris that is then vacuumed. Ozone is sometimes used to kill microbiological contaminants, and chemical biocides are often used to prevent their future growth. But the use of both ozone and chemical biocides in duct work is controversial. Little research has been conducted on the effectiveness of ozone and chemical biocides when used in ductwork, and some people have adverse health reactions to these substances.

Some duct cleaners may recommend application of a coating or sealant over dust and dirt, but laboratory tests of this procedure indicate that sealants usually do not completely cover duct interior surfaces. And concerns about this approach are over toxicity characteristics under normal use and in case of fire. Also, little is known about long-term performance of sealants and whether they break down over time and add particles to duct air.

The use of flexible, insulated and internally lined ducts has increased over the past twenty years. Some insulated duct work is not internally lined, which leaves fiberglass surfaces vulnerable to dirt and moisture accumulation. If these ducts become contaminated with biological contaminants, duct replacement is the only option.

As with other indoor air quality issues, source control of potential duct pollutants is an effective preventive strategy. Moisture control in the home and proper maintenance of heating, ventilating or cooling equipment may be all that is necessary for ductwork that will not contribute to indoor air pollution. back to top


Cochrane, C. (1998). Emerging Strategies in HVAC System Cleaning, Indoor Environment Review, 8(4), 16-17.

U.S. Environmental Protection Agency (1997). Should You Have the Air Ducts in Your Home Cleaned? Washington: U.S. EPA (EPA-402-K-97-002).


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