Carbon Monoxide Detector Beeping? What It Means and What to Do

Quick answer: If your carbon monoxide (CO) detector is sounding a loud, repeating alarm, often four quick beeps then a pause, get everyone outside into fresh air and call 911 from outside. Don't stop to search for the cause. If it gives a single chirp every 30 to 60 seconds, that's usually a low battery, an end-of-life warning or a fault, not carbon monoxide. Check the label for your model. After any real CO alarm, have your furnace, boiler and water heater inspected before using them again. Our 24/7 emergency line is (732) 779-7106.

Carbon monoxide is a gas with no color, taste or smell, so the alarm is your only warning. Knowing the difference between an emergency alarm and a maintenance chirp could save your family's lives, and it can save you a panicked night over a battery. Here's how to tell them apart.

Alarm or chirp? How to tell

Patterns vary between brands. Check the label on the back of your detector or the manual. When in doubt, treat it as a real alarm.

If the alarm is sounding: do this now

1. Get everyone outside, including pets. Don't stop to open windows or search for the source.
2. Call 911 from outside.
3. Account for everyone, and check anyone who seems unwell.
4. Don't go back inside until emergency responders say it's safe.
5. Tell responders about your fuel-burning appliances: furnace, boiler, water heater, fireplace, stove, generator or car in the garage.

Symptoms of CO exposure include headache, dizziness, nausea, weakness, confusion and sleepiness. They often feel like the flu. Symptoms that improve when you leave the house, or that affect several people or pets at once, are a strong warning sign. Get medical help right away.

After the all-clear

The fire department may ventilate the house and identify the source. Before you use the equipment again:

• Don't restart the suspected appliance until it's inspected and repaired.
• Have a licensed technician inspect the furnace or boiler, venting and water heater.
• Ask for combustion and CO readings, and photos of anything found.
• Replace the detector if it's old or was the one that alarmed. Check your manual.

Common carbon monoxide sources in New Jersey homes

• Furnaces: a cracked heat exchanger, poor combustion or a blocked flue. See cracked heat exchanger signs.
• Boilers: venting problems, poor combustion or a blocked chimney.
• Water heaters: especially when venting changed after a furnace replacement. See gas water heater pilot problems.
• Blocked vents: snow, ice, leaves or nests on plastic vent pipes and chimneys.
• Generators: running in a garage, basement or too close to windows during outages.
• Cars: running in an attached garage, even with the door open.
• Gas stoves and fireplaces: blocked flues or poor ventilation.
• Space heaters that burn fuel, used indoors.

See carbon monoxide and furnace safety and HVAC smells and what they mean.

Why winter brings more CO alarms

Heating systems run for hours, windows stay shut and storms bring generators and blocked vents. At the Jersey Shore, outages from nor'easters lead more people to run generators, which is one of the most dangerous sources. Keep generators outdoors, well away from doors, windows and vents, and follow the manufacturer's instructions.

If it's just chirping

A chirp is a maintenance message, but don't ignore it:

1. Check the label for a replace-by date.
2. Replace the battery if your model uses replaceable batteries.
3. Press test after replacing it.
4. If it keeps chirping, it may be at end of life. Replace the unit.
5. Never remove the battery and leave the detector dead.

Many detectors last roughly 5 to 10 years, but follow your model's date. A sealed 10-year unit can't have its battery replaced, so replace the whole detector.

Where to put CO detectors

Follow the manufacturer's instructions and local requirements. General good practice:

• On every level of the home, including the basement
• Outside each sleeping area
• Near (but not right next to) fuel-burning appliances
• Inside or near a room above an attached garage
• Away from bathrooms, windows and vents that could affect readings

Test them monthly with the test button.

Prevention: the best protection

• Book a yearly heating inspection with combustion and CO checks. Our $89 heating tune-up includes a safety inspection (terms apply).
• Keep vents clear of snow and debris after every storm.
• Have venting checked whenever a furnace, boiler or water heater is replaced. Changing one appliance can affect how another vents.
• Change filters to prevent overheating.
• Fix problems early: soot, rust, a yellow flame or frequent lockouts are warning signs.

See how to reset your furnace safely, which explains when a reset is the wrong move.

When to call a technician

• Your CO alarm sounded, even once
• You see soot, rust or scorch marks near the furnace or boiler
• The flame is yellow or wavering
• The furnace rollout switch has tripped
• People feel ill indoors and better outside

Myths that put families at risk

• "I'd smell it." Carbon monoxide has no smell. The rotten-egg smell people associate with gas leaks is an odorant added to natural gas, not CO.
• "The alarm is probably wrong." False alarms happen, but you can't tell from inside the house. Treat every full alarm as real until responders say otherwise.
• "Opening a window fixes it." Fresh air helps, but it doesn't remove the source. Get out first; let professionals find the cause.
• "A newer furnace can't produce CO." Any fuel-burning appliance can, if venting is blocked or combustion is poor.
• "My smoke alarm covers CO." Only combination units detect both. Check the label.
• "It only happens in old houses." Blocked vents, generators and cars in garages affect new homes too.

A simple monthly routine

1. Press the test button on every CO and smoke alarm.
2. Check the replace-by date on the label.
3. Glance at outdoor vent pipes and clear any snow, ice or leaves.
4. Look at your furnace and water heater area for soot, rust or water.
5. Make sure everyone in the home knows the alarm sound and the plan: get out, then call 911.

It takes five minutes and covers the most common risks.

Questions to ask after a CO alarm

When a technician inspects your equipment afterward, ask:

• Which appliance was the likely source, and how did you confirm it?
• What were the combustion and CO readings, before and after any repair?
• Is the venting sized and sloped correctly for every appliance that uses it?
• Is there any damage to the heat exchanger, and can you show me photos?
• Is it safe to use the appliance now, and what should I watch for?

A good technician will answer each one clearly.

Safety checks from a licensed team

Our work is performed under NJ Master HVACR License 19HC00767800, by our own licensed team. We inspect furnaces, boilers and water heaters across all 153 towns in Ocean, Monmouth, Burlington and Middlesex counties, including Lakewood, Jackson, Middletown and Woodbridge.

If your alarm is sounding, call 911 first. For an inspection afterward, book online or call (732) 779-7106. We answer 24/7.