If you heat the home with oil, gas, have a Wood Burning fire place or Wood Burning Stove YES you do have a chimney. The chimney is a vertical structure incorporated into a building and enclosing a flue or flues that carry off smoke.
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.
The smell is due to creosote deposits in the chimney, a natural byproduct of woodburning. 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.
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.
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.
I have an 80 year old home that was a longtime rental house. I have lived here five years and have been using the fireplace for four of those years. I do not know how long it has been since my chimney was swept (potentially decades, if ever). I just had a chimney sweep at my house and he informed me that the creosote in my chimney was quite thick (he used the term "level 3" creosote). He also said that in the smoke chamber, the brick is stepped (instead of smooth) and that there is a lot of dangerous buildup in there. He recommended two applications of an acid cleaning (which he said are not entirely foolproof, and work better above 45°F) and that we use a chemical when we burn our fire to help "chalkify" the creosote buildup. He showed me the buildup inside with a light and everything he said seemed to make sense. Does this sound like it's on the up and up? I can't find any info on this acid cleaning and I would like to know if this sounds like it is the proper course of action in a case like mine.
What you have described sounds pretty typical. In addition to the chemical treatment that you mentioned, professional-grade chemicals, usually in the form of a powder, can be applied by chimney sweeps to help change the nature of the glazed creosote to a form that can be removed by a professional with a brush Both forms of these products require some heat such as you would find in a small fire in the fireplace.
If the creosote is gummy, about the only way to deal with the creosote is with a chemical treatment or with an acid application. Acid applications are not as commonly used since they are harder to apply and have to be neutralized a few days after application. If the creosote is crusty or fractures when hit (as opposed to gummy) a rotary cleaning can be helpful. Read our position statement on chemical chimney cleaning products here.
Your past experiences with chimney sweeps sound as though the sweep did the job he was hired to do. However, your most recent experience sounds a bit odd. If the sweep agreed to do a complete sweeping and only cleaned the brick in the fireplace firebox, you did not get the service that you paid for. A complete chimney sweeping includes the chimney flue and smoke chamber.
In the future you could ask for a Level 1 chimney inspection and a chimney sweeping. If the sweep doesn't know what a Level 1 inspection is, find one that does. A Level 1 inspection is detailed in the National Fire Protection Association 211: Standard on Chimneys, Fireplaces, Vents and Solid Fuel-Burning Appliances.
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.
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.
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."