Short answer
If the CO alarm sounds its alarm pattern, get everyone outside and call 911. Don't go back in until responders say it's safe. Then have a licensed HVAC tech test every gas appliance before using them again. A single chirp every 30–60 seconds usually means a low battery or end of life.
Alarm vs. chirp
An alarm is a loud repeating pattern, usually four beeps. A chirp is a single short sound at intervals, which signals battery or end-of-life.
Common sources
Furnaces, water heaters, gas ranges, fireplaces and running vehicles in attached garages.
- Blocked or disconnected flue
- Cracked heat exchanger
- Backdrafting water heater
- Car warming up in the garage
What the tech does
Measures CO at each appliance and in the living space, inspects venting and the heat exchanger, and shuts off unsafe equipment.
Questions
Where should CO alarms go?+
Outside each sleeping area and on every level, following the manufacturer's instructions.
Editorial note: this guide is general information for homeowners, not a diagnosis. Desertline Heating & Air is a referral service; a licensed contractor should inspect your equipment before repairs.