A carbon monoxide alarm only helps if it can sense the gas and wake you up. Where you put it matters as much as owning one.
The basic rules
- One on every level of the home, including the basement
- One outside each sleeping area, within earshot of the bedrooms
- Not directly beside the fireplace, where a brief puff can cause false alarms
- Away from kitchens, bathrooms and very humid spaces
Height and type
Carbon monoxide mixes evenly with air, so height is less critical than people think. Follow the maker instructions. Plug in units with battery backup are a good choice for bedrooms, and combination smoke and CO alarms save wall space.
Maintenance schedule
| Task | How often |
|---|---|
| Press the test button | Monthly |
| Replace batteries | Twice a year |
| Replace the alarm | Every 5 to 7 years, check the label |
| Chimney inspection | Yearly |
The CPSC and NFPA both publish placement guidance. An alarm is a backup, not a fix, so keep the chimney itself in good shape with a yearly inspection and read how a blocked flue can send exhaust indoors.
How Carbon Monoxide Enters the Home
Carbon monoxide forms whenever fuel burns incompletely. A blocked flue, cracked liner, closed damper, downdraft or malfunctioning appliance can send it into living spaces. Because it has no color or odor, an alarm is the only way to detect it. Fireplaces and wood stoves are a common source, especially in tightly sealed homes.
Alarm Placement Rules of Thumb
- Install an alarm on every level of the home, including the basement
- Place one outside each sleeping area
- Follow the manufacturer instructions for height, since CO mixes with air
- Keep alarms away from fuel burning appliances to avoid false alarms from startup
- Do not install behind furniture or curtains
Specific Placement Near a Fireplace
Put an alarm in the room with the fireplace, but not directly over it. Keep it at least a few feet from the opening so it does not respond to normal startup gases. Also place one in adjoining bedrooms.
Maintenance
- Test monthly
- Replace batteries at least twice a year
- Replace the unit according to the date on the back, usually 5 to 7 years
- Consider models with a digital display and a memory function
What to Do if the Alarm Sounds
Move everyone to fresh air, call 911 and do not re-enter until the fire department clears the home. Have the chimney and appliances inspected before using them again.
Frequently Asked Questions
Do I need an alarm with a gas fireplace
Yes. Gas appliances also produce carbon monoxide if they malfunction.
Are combination smoke and CO alarms fine
Yes, if they meet current standards.
Does Connecticut require CO alarms
Connecticut requires alarms in many residential settings. Check your local code.
Local Help and Related Reading
Our crews handle chimney sweeps in Stamford, chimney repair in Greenwich, chimney caps in Norwalk and chimney cleaning in Danbury. Browse every town on our service areas page or our services.
More to read: Gas Fireplace Maintenance Before Winter in Connecticut, Seasoned Firewood Guide for Connecticut Homeowners, Storm Damaged Chimney? How to Handle the Insurance Claim in Connecticut.
For wider guidance, see the EPA Burn Wise program, the U.S. Department of Energy and CT DEEP.
