Frequently Asked Chimney Questions
Q. How often should I have my chimney cleaned?
This a tougher question than it sounds. The simple answer is: The National Fire Protection Association Standard 211 says, “Chimneys, fireplaces, and vents shall be inspected at least once a year for soundness, freedom from deposits, and correct clearances. Cleaning, maintenance, and repairs shall be done if necessary.” This is the national safety standard and is the correct way to approach maintenance if you don’t use your chimney frequently. Animals may build nests in the flue or there may be some kind of deterioration that could make the chimney unsafe to use. The Chimney Safety Institute of America recommends that open masonry fireplaces should be cleaned at 1/8″ of sooty buildup or sooner if there is any glaze present in the system. Factory-built fireplaces should be cleaned when any appreciable buildup occurs. This is considered to be enough fuel buildup to cause a chimney fire capable of damaging the chimney or spreading to the home.
Q. My fireplace has a strong odor, especially in the summer. What can I do?
The smell is due to creosote deposits in the chimney, a natural byproduct of wood burning. The odor is usually worse in the summer when the humidity is high and the air conditioner is turned on. A good cleaning will help but usually won’t solve the problem completely. There are commercial chimney deodorants that work pretty well. Many people have good results with baking soda or even kitty litter set in the fireplace. The real problem is that air is being drawn down the chimney, a symptom of overall pressure problems in the house. Some make-up air should be introduced somewhere else in the house.
A tight sealing, top-mounted damper also will reduce this air flow coming down the chimney.
Q. When I build a fire in my upstairs fireplace, I get smoke from the basement fireplace.
This has become quite a common problem in modern air tight houses where weather-proofing has sealed up the usual air infiltration routes. The fireplace in use exhausts household air until a negative pressure situation exists. If the house is fairly tight, the simplest route for makeup air to enter the structure is often the unused fireplace chimney. As air is drawn down this unused flue, it picks up smoke that is exiting nearby from the fireplace in use and delivers the smoke to the living area. If the chimney has been video scanned and has no breaches or missing mortar joints then the best solution is to provide makeup air to the house so the negative pressure problem no longer exists, thus eliminating not only the smoke problem, but also the potential for carbon monoxide to be drawn back down the furnace chimney. A secondary solution is to install a top-mount damper on the fireplace that is used the least.
Q. I heat with gas. Should this chimney be checked too?
Without a doubt! Although gas is generally a clean burning fuel, the chimney can become non-functional from bird nests or other debris blocking the flue. Modern furnaces also can cause many problems with the average flues intended to vent the older generation of furnaces because the flue gases can condense before venting into the atmosphere as intended. A properly sized liner will solve this issue.
Q: What is 3rd stage creosote or glazing?
Creosote is unburned fuel. Stage three is the shiny, black, waxy creosote deposit. This type does not sweep off like 1st stage (black dust like creosote) or 2nd stage (dust-like particles build start to curl up). If the creosote is gummy, about the only way to deal with the creosote is with a chemical treatment (Cre- Away, creosote modifier) or mechanical cleaning (Rho Kleen/Wizard Clean). Acid applications are not as commonly used since they are harder to apply and have to be neutralized a few days after application.
Q: Why do I need a chimney cap?
Chimney caps protect the flue from rain, leaves, birds, raccoons and squirrels. The rain can end up in your fireplace and on your outer hearth. Birds can be noisy and, as in the case of Chimney Swifts, are sometimes federally protected migratory birds that cannot be removed. You have to wait until they leave (mid September/ early October) then sweep the chimney and cap it. Raccoons and squirrels can bring fleas into the home as well as urinate and defecate on the smoke shelf. If the damper is left open, squirrels have been known to venture into the home and wreak havoc trying to get back outside. Raccoons will usually stay in the chimney and climb in and out.
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