Follow the instruction above. The correct call here is the utility, 911, or a doctor, and putting a contractor number on this page would be indefensible.
1What to do right now
- Get outGet everyone and every pet outside into fresh air. Don’t stop to open windows or look for the source.
- Call from outsideCall 911 or the fire department once you’re outside. If you suspect a gas appliance, you can also call your gas utility’s emergency line from outside.
- Get medical helpIf anyone has symptoms, or has been asleep in the house, tell the dispatcher. Carbon monoxide poisoning needs medical treatment.
- Stay outDon’t go back in until the fire department or utility says it’s safe.
2Why chimneys and flues can cause it
Carbon monoxide is made when fuel burns. A working chimney or vent carries it outside. When something stops that happening, it can end up in the house. Common chimney-related causes include:
- A blocked flue. Nests, debris or collapsed masonry can stop gases escaping.
- A damaged or missing liner. Gases can leak through cracked mortar into the house.
- The wrong flue for the appliance. A gas appliance on an oversized old flue may not draft properly.
- A fireplace damper closed while a fire or gas logs are still burning.
Working out the cause is the responders’ and technicians’ job, not yours. Don’t go looking for it while the alarm is sounding.
3After the emergency
- Don’t use the fireplace, stove, furnace or water heater again until the source has been found and fixed by a qualified technician.
- Don’t attempt your own repairs to gas venting, flue connections or liners.
- Replace the alarm if it’s past the replacement date on its label, and check you have alarms near sleeping areas and on each level.
Gas venting and flue liners are not do-it-yourself work. A mistake there is how carbon monoxide gets into a house in the first place.
4Preventing it next time
- Inspect yearlyNFPA 211 recommends having chimneys inspected once a year.
- Test alarms monthlyPress the test button and replace batteries as the maker directs.
- Keep the flue openA cap keeps nests and debris out; see no cap on the flue.
- Assess before you swap appliancesA new gas appliance on an old flue needs a venting assessment.
5Questions
What if nobody feels sick?
Leave anyway and call. You can’t see or smell carbon monoxide, and symptoms can come on without warning.
What if the alarm stops when I open a window?
That doesn’t mean the problem is gone. Get out and call 911 or the fire department from outside.
Could it just be a bad alarm?
Don’t assume so. Let the fire department or utility test the air first. Check for a low-battery or end-of-life chirp only after they’ve cleared the house.
Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.
