Quick answer
Carbon monoxide (CO) is an invisible, odorless gas produced by burning fuel. A blocked, cracked or improperly sized chimney flue can let CO back into the home. Install CO alarms on every level and near sleeping areas, and have every chimney and vent inspected once a year.
How chimneys leak CO
- Blockages from nests, debris or collapsed tiles
- Cracked or missing liners letting gases seep through masonry
- Oversized or undersized flues for furnaces and water heaters
- Negative air pressure pulling exhaust back down
Symptoms of CO exposure
Headache, dizziness, weakness, nausea, confusion and flu-like symptoms that improve when you leave the house. If you suspect CO, get everyone outside and call 911.
Prevention
- CO alarms on every level and outside bedrooms
- Yearly inspection of every flue — fireplace, furnace, boiler and water heater
- A cap to keep animals and debris out
More questions
Can a gas furnace chimney cause carbon monoxide?
Yes. Furnace and water-heater flues are a common source when they are blocked, corroded or the wrong size.
Need a local professional?
Chimney Champs has been a local chimney company for 13 years. We provide chimney inspection in your area. Call (856) 300-9215 for a free estimate.
Sources & further reading
- U.S. Consumer Product Safety Commission — carbon monoxide safety
- U.S. Fire Administration — home heating fire safety
- NFPA 211 — Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances (National Fire Protection Association)
Keep reading
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- What to Do in a Chimney Fire (and How to Prevent One)
- Animals in Your Chimney: Birds, Raccoons and Squirrels — What to Do
- How Often Should You Clean Your Chimney?
- 9 Signs Your Chimney Needs Repair
- Chimney Inspection Levels 1, 2 and 3 Explained