Q. How often should I have my chimney swept?
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 the problem. It takes into account the fact that even if you don’t use your chimney much, animals may build nests in the flue or there may be other types of deterioration that could make the chimney unsafe to use.
The Chimney Safety Institute of America recommends that open masonry fireplaces should be swept at 1/8″ of sooty buildup, and sooner if there is any glaze present in the system. This is considered to be enough fuel buildup to cause a chimney fire capable of damaging the chimney or spreading to the home. Factory-built fireplaces should be swept when any appreciable buildup occurs. The logic is that the deposit is quite acidic and can shorten the life of the fireplace.
Q. My fireplace stinks, 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 sweeping will help but usually won’t solve the problem completely. There are commercial chimney deodorants that work pretty well, and many people have good results with baking soda or even kitty litter set in the fireplace. The real problem is the air 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 will also 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. 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 can also cause many problems with the average flues intended to vent the older generation of furnaces. We suggest you check the areas on gas and carbon monoxide for more information.
Q: How common is it that chimney liners cannot be seen from inside the fireplace using only a flashlight? Is there some standard building requirement for the flue and the fireplace that you can’t just look up from the fireplace and see the sky or chimney cap at the top of the chimney?
Flues are allowed to have up to 30 degree offsets. In most cases this will make a direct visual observation of the flue impossible. A video scan would be required to evaluate the flue condition. The height of the chimney flue is not a factor. There is a big difference in what is observed between a visual inspection and a video inspection, even in short flues.
Q. What stainless steel liners require insulation?
Liners for gas and oil-fired appliances do not require insulation to meet the manufacturers’ installation and warranty requirements. Because of the lower flue gas temperatures and lesser heat transfer they are less likely to catch surrounding combustible material on fire. Those that are used with solid fuel-burning appliances do, however. If combustible materials are in contact with the chimney there are provisions that allow the liner to be installed in what is defined as a zero/zero install. That means there may be zero clearance to the interior of the chimney and zero clearance to the exterior of the chimney . The insulation may be of the blanket type or an expanded mica or masonry insulation. There are some manufacturers that will list a liner for use without insulation if it conforms to the NFPA 211 construction requirements. The problem is that it is almost impossible to determine that without destroying the chimney. It makes much more sense to insulate every liner serving a wood burning appliance. Even gas and oil-fired appliances that are vented into an exterior chimney will benefit from insulating the liner.
Q. What’s safe to burn in the fireplace?
Only well-seasoned wood.
Q: I’m unsure how to work my damper. Can you should me how?
This is a common question. If the damper is not functioning correctly or if it’s closed, you’ve got a situation on your hands that may lead to a smoky room at best and a fire hazard at worst. The damper is a hinged metal plate or valve used to seal the fireplace when not in use. You want the damper to be fully open, and you want it to be in the open position before you light your fire, for obvious safety reasons.”
Q: What is your position on chemical chimney cleaners?
The Chimney Safety Institute of America (CSIA), a non-profit, educational institution focused on the prevention of chimney and venting hazards, is concerned about the consumer use of chemical chimney cleaning products to the exclusion of conventional chimney inspections and cleaning. These products often are promoted for their ability to remove a portion of the creosote from a masonry or metal chimney interior through catalytic action when burned in a fireplace or wood stove. The CSIA believes that the use of these products alone is not an adequate substitute for mechanical chimney cleaning and inspection because it does not provide the same level of protection to the chimney system. Current promotional claims for some of the products may be creating a false sense of security among consumers.
It is the consensus of qualified experts that chimney maintenance is best achieved through annual inspections, and mechanical sweeping, by trained professional chimney sweeps as frequently as needed. Chimney inspections often reveal hidden problems with a chimney structure that could be potentially hazardous. Mechanical sweeping of chimneys not only removes layers of creosote from the chimney surface, it removes the resulting loose soot and creosote from the chimney, fireplace, or wood stove. A substantial percentage of fireplace and wood stove chimneys do not provide a straight path from the firebox to the outside. If chemical chimney cleaning products perform as claimed and cause debris in the chimney to fall, that debris still needs to be removed from the smoke shelf, baffle, catalytic combustor, or offset in order to ensure a properly functioning chimney.
Chemical products that claim to clean or assist in cleaning chimneys are not new. Indeed some of these chemical products are used successfully by professional chimney sweeps in conjunction with the mechanical cleaning of a chimney. In some situations a chimney can develop a hard or tacky layer of creosote in the chimney that cannot be removed by normal mechanical brushing. Under the supervision of a qualified chimney professional certain chemical cleaners may be used to change the chemical composition of the hard or tacky layer of creosote into a brittle or powdery condition to facilitate its removal.
CSIA believes that the optimal method for cleaning a chimney is by a mechanical brushing of the chimney in conjunction with a complete evaluation of the system by a qualified chimney professional. The CSIA and the National Fire Protection Association recommend annual inspections.