Although winter has not officially arrived, we have already experienced below-freezing temperatures. Furthermore, the Farmer’s Almanac has predicted that this coming winter will be even colder than the past few brutally cold winters we have experienced. As the temperatures are falling, heating bills are going up unfortunately. We at Blue Ridge Chimney Services enjoy helping our customers save money and heat their homes more efficiently. We would like to tell you about one of the reasons why heating costs can be so expensive: the stack effect, or also known as the chimney effect. Involving the physics of air pressure, this effect causes cold outside air to compete against the warm inside air in your house. The stack effect can also be responsible for smoke entering your home. We would like to answer some questions about how the cold air of winter impacts your chimney with the stack effect and how you can avoid this from happening in your home.

The Stack Effect - Shenandoah Valley VA

Image by Kimbar under the Creative Commons license.

What exactly is the stack effect?

According to the Wood Heat Organization, the warm indoor air wants to rise, especially when the outside air is significantly colder. These temperature differences affects the pressure inside your home. The stack effect occurs when the air pressure on the lowest level of your home is lower, or negative, and the air pressure on the upper floors of your house is higher.

How does the stack effect affect my chimney and venting system?

When cold air leaks into your home, the air pressure balance worsens. Your chimney is one of the main areas where air leaks occur. Creating negative air pressure, the cold air entering your home makes the stack effect strong enough to force a cold backdraft in a fireplace chimney that is cooler than room temperature. Trying to light a fire in a chimney with a backdraft will cause smoke to enter the room where the fireplace is located instead of out the chimney.

What are the best ways to avoid chimney and fireplace problems related to the stack effect?

The Wood Heat Organization suggests solutions that can help you avoid the two main chimney stack effect-related problems:

  • When No Fire Is Burning, Cold Air Is Entering Into the Home Through the Chimney. If you are experiencing this problem, the stack effect has caused a backdraft of cold outdoor air out of your fireplace. You might also notice smoky odors from the chimney exhaust air that has entered your home through the fireplace. Many chimneys are designed with an exterior wall to save living space; however, one of the best ways to prevent the stack effect is to install the chimney inside your home to keep it in a warm environment. Blue Ridge Chimney Services can show you various different designs and styles of interior chimneys we can install in your home that will add both warmth and beauty to your living space as well as utilize as less space as possible to give you more room.
  • When You Open Your Fireplace Doors, Smoke Blows Into the Room. The stack effect can restrict your chimney’s exhaust flow. As a result, opening the doors to your fireplace or stove causes trapped smoky air to come out of the chimney. The best solution to this problem is having a straight chimney. If your chimney has 90 degree turns and offsets, your chimney has places where smoke can get trapped; straight chimneys make it easier for the smoke to go directly out your chimney and not linger.

Want to learn more about the stack effect? Contact Blue Ridge Chimney Services to find out more about the stack effect and other winter-related chimney problems from our expert staff.