Short answer
A furnace can release carbon monoxide if its heat exchanger is cracked, its vent is blocked, or combustion is poor. Warning signs include a yellow or flickering flame, soot, stuffy air, and headaches that ease when you leave home. If a CO alarm sounds, get everyone outside, call 911 or the fire department, and do not re-enter until cleared.
How CO forms
Incomplete combustion makes carbon monoxide. Normally the vent carries it outside. Cracks or blockages let it into the home.
Warning signs
CO is odorless, so detectors matter most.
- Yellow, lazy or flickering burner flame
- Soot around the furnace
- Condensation on windows
- Headache, dizziness or nausea at home
Not sure it is safe to keep running? A local technician can check it today.
Call NowDetectors
Massachusetts requires CO alarms on every level of homes with fuel-burning appliances. Test monthly and replace per the manufacturer's date.
If the alarm sounds
Leave immediately, call 911, and have the furnace inspected before using it again.
Related questions
Can a new furnace leak CO?
Yes, if venting is damaged or installed wrong. Annual service checks this.
Where should CO detectors go?
On every level and near sleeping areas.
Services that fix this
Emergency Heating Repair
No heat on a cold night, CO alarms and furnaces that will not restart.
Emergency heating repair in Marlborough
Furnace Repair
Gas and oil furnaces that will not heat, blow cold, short-cycle or make noise.
Furnace repair in MarlboroughThis guide is general information for homeowners, not a diagnosis of your system. For anything involving gas, carbon monoxide, electricity or active leaks, stop and call a qualified professional.
