It’s common to find remedy from the odor by cleaning the creosote and soot out of the chimney. Hot, humid summer days and rainy days adding moisture will product undesirable odors from a dirty chimney. A chimney cleaning will also find any decomposing material problems and will also clean the creosote out of the chimney. The creosote soaks into the chimney walls so even after a chimney cleaning is complete this may continue to contribute to the smell. Although, as long as the draft is working correctly and there is no negative air flow in the home, the smell should not enter your home.
If the chimney inspection and cleaning does not rid the home of the odor, next it is best to seal the chimney from water sitting in the chamber and causing a musty smell. This can be done by installing a top mounted damper or chimney rain cap to keep the rain water and moisture out. The top mounted damper is your best bet for sealing the chimney off from rain and humidity and it prevents animals and leaves from getting into the chimney shaft as well.
After the water issues are taken care of, the next concern is the air pressure in the home. Most chimneys will have some type of smell to them, but this is typically not a problem because the chimney draft drives this smell out of the flue and away from the inside room. But when there is negative air pressure in the home, air has to come from somewhere to fill this vacancy. Because the chimney has a low point of resistance, this additional air typically comes through here, bringing the chimney odors along with it. Often found in newer tight homes, this negative air pressure can reverse the flow of draft from the chimney back into the home. This problem also often shows up during the warmer months after weatherizing has been done to the home or venting changes and improvements have been made. Other causes of the negative air pressure include exhaust fans, central vacuum, additional chimneys, combustion appliance flues, range hood, and the installation of many more household appliances.
A quick solution to the negative air pressure is to crack a window at all times to let the pressure change through this outlet rather than the chimney. But for a more permanent approach to the negative air pressure, follow these steps till the smell no longer enters the home.
1. Close the fire damper when the fireplace is not in use. While this will sometimes solve the problem, most dampers are not perfectly sealed, so they problem may still occur.
2. Have a glass fire screen installed to keep the warm air from escaping when there is a fire in the fireplace.
3. Have a professional install a top sealing damper onto the top of the chimney that is controlled by a metal chain and hangs down the chimney to the hearth. These can be a huge help in monitoring the airflow.
4. Provide outside combustion air to other combustion appliances that started the air pressure problem in the home.
The smell could be a result of a number of problems, here is a quick guide to discovering the source of the odor.
If your chimney smells like ——– Then it most likely is from…
Bad Barbeque/Asphalt ————- Creosote build up
Musty Odor ————————– Water sitting in your smoke chamber
Rot and Decomposition ———— Fallen leaves combining with damp soot and rotting in the chimney
Animal Scat or Dead Critters —— Animals leaving behind thoughtful “gifts” in your chimney or not being able to escape and passing away
It is never a bad time to get a chimney inspection. Even in the middle of the summer, with months till you even start to think about cold weather activities, chimney professions are available to inspect and clean your chimney. Don’t let an intrusive smell draw all of the attention, take care of the odor as soon as it is noticed and enjoy your fireplace all year long.