Carbon Monoxide and Your Furnace: Safety Signs Every Gas-Heat Home Should Know
A gas furnace that's working right vents carbon monoxide safely outside. Know the warning signs, put CO detectors near every sleeping area, and have your furnace checked every year.
If your CO alarm goes off, or anyone in your home feels dizzy, sick to their stomach, or has a sudden headache, get everyone outside to fresh air and call 911. Don't go back in until emergency responders say it's safe.
Carbon monoxide (CO) is a gas you can't see or smell. A gas furnace that's working properly sends it safely outside through the vent pipe. When something goes wrong, it can build up inside your home. The CDC reports more than 400 deaths and more than 100,000 emergency room visits from accidental CO poisoning in the U.S. each year.
What are the symptoms of carbon monoxide poisoning?
According to the CDC, the most common symptoms are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. They're often mistaken for the flu.
One clue: symptoms that ease when you leave the house and come back when you return. Another is several people, or pets, getting sick at the same time.
What are the warning signs at the furnace?
- A yellow or flickering burner flame instead of a steady blue one
- Soot or dark stains around the furnace or vent pipe
- A vent pipe that's loose, rusted, or disconnected
- Extra moisture on windows near the furnace
- A furnace that keeps shutting off or won't stay lit
If you notice any of these, turn the furnace off and call a technician. Don't try to repair the venting or burners yourself.
Where should I put carbon monoxide detectors?
The CDC recommends battery-operated or battery-backup CO detectors near every sleeping area. Many homeowners also add one on each level of the home and one near the furnace. Follow the instructions that come with your detector for exact placement.
Test your detectors monthly, check the batteries when the clocks change in spring and fall, and replace the detector on the schedule the manufacturer gives, often about every 5 to 7 years.
How do I keep my furnace safe?
- Get a yearly furnace inspection. The CDC recommends having gas appliances serviced every year. Our furnace tune-up includes a carbon monoxide test and a heat exchanger inspection.
- Keep the area around the furnace clear. Don't store boxes, paint, or cleaning supplies against it.
- Change your air filter. A clogged filter can cause a furnace to overheat. See how often to change your air filter.
- Keep outdoor vents clear of leaves, nests, and debris.
Can a cracked heat exchanger cause CO?
A crack in the heat exchanger can allow combustion gases to mix with the air your system blows through the house. It's one of the main things we look for during a heating inspection. If we find one, we'll show you what we found and explain your options.
When should I call a pro?
For a CO alarm or symptoms, call 911 first. For any of the furnace warning signs above, turn the furnace off and call Aero Air Services at (888) 409-2376. We answer 24/7 for heating emergencies. For a yearly safety check, request service online.
Frequently asked questions
Do heat pumps produce carbon monoxide?
No. All-electric heat pumps don't burn fuel. A home with a gas furnace backup, gas water heater, gas stove, fireplace, or attached garage should still have CO detectors.
Can I smell a carbon monoxide leak?
No. CO has no smell. The rotten egg smell is natural gas, which is a separate danger. For either one, leave the house and call 911 or your gas company from outside.
How often should my furnace be inspected?
Once a year, ideally in the fall before you need heat.
Chevy Gonzalez is the HVAC General Manager at Aero Air Services, a family-owned HVAC company serving homeowners across Northwest Metro Atlanta.