How Your Chimney Really Works

If you’re like most homeowners with a wood-burning fireplace or heating stove, you look forward to cozying up to a glowing fire. A properly functioning chimney is essential to the performance of your fireplace or heating stove. But do you know how a chimney works? Let’s take a closer look at the science behind the chimney. It may even help you spot any issues in your home.

Oxygenation is Important

When you strike a match to light the fire, the oxygen inside the fireplace will cause the wood logs to combust. Without enough oxygen in the fireplace, there is no fire. So, if you’re having trouble getting the fire started, you probably don’t have sufficient draft flow. That’s why your damper must be open to light the fire and keep it going.

Negative Pressure

Chimneys are negative pressure systems. And for the chimney and heating appliance to operate safely and efficiently, there needs to be sufficient draft and airflow in your home. The volume of oxygen that flows in must be equal to the amount of oxygen expelled. The draft is created when the colder and heavier outside air enters the fireplace. Even though you may have your doors and windows closed, the air is flowing through vents and tiny cracks in your home. This negative air flow is constant, whether you are using the fireplace or not.  As the colder air is flowing in from below, the warmer, lighter air is rising to the top and venting through the chimney along with smoke, soot, and gasses, known as the stack effect. 

When there is too much draft, more heat will be sucked out of the chimney. It commonly occurs when you have an open door or window when using the fireplace. Gaps in the masonry due to chimney damage can also cause chimney draft problems. Not enough draft is another problem. It usually occurs when there isn’t enough fresh air coming in. The damper may be closed; obstructions could be blocking the flue or there is excessive creosote in the chimney, among others. It causes a smokey and hazardous fireplace that increases the risk of carbon monoxide poisoning. 

Using Different Types of Firewood

There are several ways to increase the draft or air pressure in your chimney. One way is to burn hotter to create more draft. Different firewoods burn at different temperatures. For example, Red Oak, Sugar Maple, and Yellow Birch burn hotter than Aspen, Hemlock and Red Cedar. Another method is to extend the height of the chimney. The standard height of a chimney is 15 feet from the base to the top. Taller chimneys create more draft. 

Annual chimney inspections and cleaning can ensure your chimney and any attached heating appliances are working safely and efficiently. If you are experiencing drafting problems, its best to consult with a chimney professional, an inspection can reveal whether there are any damages to the structure or components that are causing drafting issues. Our chimney professionals at Chimney Saver Solutions will  recommend solutions that will resolve any issue!

Phone: 804-440-5000

9306 Old Staples Mill Rd
Richmond, VA 23228