Chimney downdrafts can cause your smoke and carbon monoxide alarms to go off. In extreme cases, they can lead to severe health problems as they can contaminate the air you breathe. Fortunately, you can call a chimney contractor to help you figure out if you have downdraft problems and what can be done to solve them.

Keep reading to learn more about chimney downdrafts.
How Your Chimney Works
Chimneys have a smoke shelf, chimney damper and crown cap. Your chimney damper controls airflow, allowing smoke to rise to your flue, cap and then outdoors. The heat pressure from your combustion source pushes the smoke and heating byproducts. Insufficient heat pressure is usually the cause of chimney downdrafts.
Causes of Chimney Downdraft
With enough pressure, smoke will escape through your flue or chimney. The causes of downdrafts include the following:
- Drafty fireplaces.
- Cracked or broken dampers.
- The “stack” effect. (When warm air rises and creates a high-pressure area above your roof, the air underneath the warm air will head downward. This will create a small vacuum that causes downdrafts.)
- Indoor exhaust fans. (These can pull air from chimneys if nearby.)
Experts recommend replacing your damper or using exhaust fans venting outdoors to reduce and avoid chimney backdraft and downdraft issues.
Signs of Chimney Downdraft
Here are the typical signs of chimney downdrafts:
- Soot on Glass. If you notice soot on your windows and glassware, this could be due to downdraft problems.
- Alarm Systems Going Off. These may seem like false carbon monoxide or smoke alarm triggers, but they can actually be chimney downdrafts emitting low smoke indoors.
- Irritated Eyes. Soot is nearly invisible, but it can irritate your eyes. If your eyes are frequently irritated, it could be due to excessive soot.
Preventing Chimney Downdrafts
Shutting off your exhaust fans when fireplaces are in use removes negative air pressure. Replacing your damaged or warped dampers will improve the chimney’s pressure retention too. Lastly, regular cleaning and inspections by contractors give you a complete understanding of your chimney’s condition and identify the steps that will help improve its performance.
High-quality chimney cleaning and sweeping only come from experienced contractors, like Batts’ Chimney Services. To request a quote, call us at (256) 660-1338 (Northern Alabama) or (205) 956-8207 (Greater Birmingham Area). You can also complete this contact form to schedule a free consultation.