If a smoke or heat alarm gives a single chirp every 30 to 60 seconds, the battery is usually low. On an alarm with a sealed 10-year battery, the chirp means the alarm has reached the end of its life and needs replacing. If the alarm goes into full alarm with no fire, the usual causes are cooking fumes, steam, dust or insects in the sensor. If the panel of a commercial fire alarm system is beeping, that is normally a fault warning. Record it and call your fire alarm maintenance company, and do not just silence it.
Always check first that there is no fire.
Quick diagnosis: what is the beep telling you?
| What you hear or see | Likely cause | What to do |
|---|---|---|
| Single chirp every 30–60 seconds | Low battery | Replace the battery, or the whole alarm if the battery is sealed |
| Chirping that continues after a new battery | End of life or a fault | Check the replacement date on the alarm. Replace it if it is due. |
| Chirps mostly at night | Weak battery affected by the cooler overnight temperature | Replace the battery |
| Mains alarm chirping with the green light not on steadily | No mains power, running on backup | Check the fuse or circuit breaker. Contact an electrician or your landlord. |
| Full alarm with no fire | Cooking fumes, steam, dust or insects | Ventilate, use the hush button, clean the alarm and review where it is sited |
| Commercial panel buzzing with a fault light on | System fault | Log it and call your maintenance company |
Home smoke and heat alarms
Low-battery chirp
The most common reason a fire alarm beeps is a low battery. Manufacturers describe a regular single chirp roughly every 30 to 60 seconds, which can carry on for several days. Replace the battery, or the whole alarm if the battery is sealed, as soon as you can.
Low-battery chirps often start in the middle of the night. Kidde explains that a weakening battery struggles more as the room cools in the early hours, so the warning tends to show up then.
End-of-life warning
Smoke and heat alarms are designed to last around 10 years, because their sensors deteriorate over time. Many alarms now have a sealed 10-year battery that cannot be changed, so when the chirp starts the whole alarm needs replacing. Look for the "replace by" date on the side of the alarm. If it has passed, fit a new alarm. Our smoke and heat alarms range includes sealed-battery and mains-powered models.
Mains-powered alarm beeping
Hard-wired alarms have a backup battery. Aico explains that if the green power light is not on steadily, the alarm is not receiving mains power and is running on its backup. Check the fuse or circuit breaker for the alarm circuit. If you are not sure, ask a qualified electrician or your landlord. Once power is restored, the chirping should stop within a couple of hours as the backup recharges. Never disconnect the wiring yourself.
Fire alarm keeps going off with no fire
False alarms are usually caused by:
- Cooking fumes and toast: the London Fire Brigade advises fitting a heat alarm, not a smoke alarm, in the kitchen.
- Steam from bathrooms and showers drifting onto a nearby smoke alarm
- Dust from building work or everyday build-up inside the sensing chamber
- Insects getting in through the grille
Gently vacuum the alarm's vents, following the manufacturer's instructions. If false alarms keep happening, the alarm may be in the wrong place or be the wrong type for that room.
Interlinked alarms: which one started it?
On interlinked systems every alarm sounds together. Look for the alarm with a flashing red LED, which is usually the one that detected the problem, and press its hush button.
How to turn off a fire alarm safely
- Check for fire first. If there is any sign of fire, get everyone out and call 999.
- Clear the air if the cause is obvious, such as cooking smoke or steam. Open a window and fan the air near the alarm.
- Press the hush or test button. On many alarms this pauses a false alarm for a short period (often about 10 minutes) before full sensitivity returns. Some models can also silence a low-battery chirp for several hours so you can replace the battery in daylight.
- Fix the cause: replace the battery or alarm, clean it, or move it with the help of your installer.
Never take the battery out or disconnect an alarm to stop the beeping. Fire and rescue service advice is to remove batteries only when replacing them, because a disabled alarm leaves you without protection.
How to change a fire alarm battery
- Check the model and the instructions. If the battery is sealed, the whole alarm needs replacing.
- For mains-powered alarms with a replaceable backup battery, follow the manufacturer's instructions. These usually tell you to switch off the mains supply to the alarm first. If you are not confident, use an electrician.
- Twist the alarm off its base or open the battery drawer.
- Fit a new battery of exactly the type the manufacturer specifies.
- Refit the alarm, restore power if needed and press the test button to check it sounds.
Our batteries collection includes 9V cells, sealed lead acid standby batteries for fire alarm panels and emergency lighting battery packs. Always match the battery to the device's instructions. Fire and rescue services recommend testing home alarms regularly using the test button. Our guide on how to test smoke detectors explains how.
Carbon monoxide alarm beeping
A carbon monoxide (CO) alarm is different. If it goes into full alarm, treat it as real. Stop using appliances, open doors and windows, get everyone outside and call the National Gas Emergency Service on 0800 111 999. If anyone feels unwell, seek medical help. A single chirp is usually a low battery or end-of-life warning, and CO alarms have their own replacement date, typically between 5 and 10 years depending on the model, so check the date on the alarm. See our carbon monoxide detectors.
Commercial fire alarm panel beeping
In offices, shops, schools and other workplaces, a beeping or buzzing fire alarm control panel usually means it has detected a fault, not a fire. Examples include a removed or failed detector, a wiring fault or a power supply or standby battery problem. The fault light and display normally show which zone or device is affected.
- Record the fault in the fire alarm log book, including the date, time and exactly what the panel shows.
- Call your fire alarm maintenance company. Faults should be investigated and put right by a competent person.
- Don't just silence the fault or disable the zone. The silence control (usually behind a key or access code) only mutes the buzzer. The fault is still there, and part of the system may not work in a fire.
- If the system is monitored by an alarm receiving centre, follow your site procedure for telling the centre.
Frequently asked questions
Why is my fire alarm beeping every 30 seconds?
A regular single chirp every 30 to 60 seconds is almost always a low-battery warning. On an alarm with a sealed battery, it means the alarm has reached the end of its life and needs replacing.
Why is my smoke alarm still beeping after I changed the battery?
The alarm may be past its replacement date, the battery may be the wrong type or not seated properly, or a mains alarm may have lost power. Check the date on the alarm and the green power light. If the alarm is more than 10 years old, replace it.
How do I stop my fire alarm beeping without removing the battery?
Press the hush or test button to pause the sound, then deal with the cause. Replace the battery or the alarm, clean dust out of the vents, or ventilate the room. Never leave an alarm without a working power source.
Why does my fire alarm keep going off when there's no fire?
The usual causes are cooking fumes, steam, dust or insects. Clean the alarm, and consider fitting a heat alarm in the kitchen and moving smoke alarms away from bathrooms.
Can I silence a fault on a commercial fire alarm panel?
Authorised users can mute the buzzer, but the fault must still be recorded and reported to your maintenance company.
This guide is general information; follow your fire risk assessment and a competent person's advice.