Draft/Flow: Summertime Chimney Issues

Unpleasant odors coming from the fireplace can, unfortunately, be common problems in the summer due to draft and flow chimney issues. Although fireplace odor issues can be the result of creosote accumulations or birds or animals living inside the chimney, quite often the bad smell is simply old smoky air from the chimney. According to the Chimney Safety Institute of America (CSIA), the air flow in your house is constantly moving, even though you cannot see it. Most often, air tries to flow out through the upper parts of your home, and air flows into the house through its lower part to try to replace the air that left. To better understand draft and flow, Hudson Chimney would like to tell you more about some of the things that influence the actual flow of air into and out of your home.



The effect on interior house pressures caused by the wind, wind-loading takes place when wind hits your home and creates high pressure on the side it hits and low pressure on the downwind side. If you open windows or doors on the windward side, this will help both to pressurize the house and increase the chimney draft. On the other hand, if you have your windows or doors on the downwind side opened, this can depressurize the house and allow the smoky air from the chimney to enter your home by backdrafting.


Clothes dryers, kitchen, attic, and bathroom fans, and central vacuum systems can remove large volumes of air and cause depressurization that leads to backdrafting. This often results in negative pressure around your fireplace, stove, or other heating appliance. Forced-air furnaces also take a large amount of air away from a home. When these systems have leaky ducts, it can negatively affect draft by causing air to be blown into the attic or crawlspace.


When you get your house weatherized to keep cooled air in during the summer and heated air in during the winter, you can possibly seal your home off too tightly to the point where air cannot flow properly. This leads to the stack effect, which is where warm air rises to the highest level and creates a pressurized area. The stack effect can be behind several chimney draft issues.

Noticing signs of chimney draft problems this summer? Contact us at Hudson Chimney to find out how we can help you solve these issues.