Why is my smoke alarm still chirping after a new battery? (UK and US)
A smoke alarm that keeps chirping after a new battery usually still remembers the old one, has the wrong battery in it, or has reached the end of its life. How to reset it, what the chirp codes mean for Kidde, First Alert, FireAngel and Aico, mains and sealed alarms, finding the chirper in a linked set, and the UK and US rules, with a chirp decoder.
HanaHow12 minute readA smoke alarm that keeps chirping after you’ve fitted a new battery usually means one of three things: the alarm still remembers the old, low battery; the new battery isn’t right for it, or isn’t seated properly; or the alarm itself has reached the end of its life, and no battery will fix that. The chirp decoder below tells you what your alarm’s chirps mean, and the sections after it go through each fix.
What does the chirp mean?
Count the chirps in one go, then pick your alarm’s make. The make is usually printed on the front, or on the label on the back or side.
Your make
What you hear
Low battery. Change it, then reset.
Kidde says a low battery chirps every 30 to 40 seconds, or every 60 seconds on some models, for at least seven days. On a sealed 10-year Kidde alarm, there’s no battery to change: replace the alarm.
- Fit a fresh battery of the type your manual lists. No rechargeables.
- Then reset it: power off at the fuse box if it’s a mains alarm, take it off its base, unplug it if it has a plug, battery out, hold the test button for at least 15 seconds, battery back in, plug back in, refit it and power on.
- Press test once so it checks the new battery.
End of life on many Kidde alarms
On the UK 10Y29 sealed alarm, one flash with two chirps every 30 seconds means its 10-year life is over. Some US Kidde alarms give two chirps every 60 seconds and say “Replace Alarm”.
- Replace the whole alarm. A new battery won’t stop this warning.
- Check the date on the back or side, and replace any other alarms of the same age.
- Renting? Tell your landlord: in England most landlords must repair or replace a faulty alarm you report.
A fault on newer Kidde alarms
On Kidde’s newer US mains alarms, such as the Detect range, 3 chirps every 60 seconds with an amber flash means a fault: a sensor error, a stuck test button or, on combined alarms, a CO sensor fault. Voice models say what it is.
- Vacuum round the slots, then press the test/hush button once to try to reset it.
- If the chirps come back, replace the alarm as soon as you can.
Check your model’s manual
4 chirps isn’t a code we found for Kidde in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Check your model’s manual
5 chirps isn’t a code we found for Kidde in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Get out now
A loud alarm that keeps going isn’t a chirp: it’s warning you about smoke, heat or carbon monoxide.
- Get everyone out and stay out.
- Call 999 in the UK or 911 in the US.
- If it’s a carbon monoxide alarm, get into fresh air. In Great Britain the gas emergency number is 0800 111 999; in Northern Ireland it’s 0800 002 001.
Low battery. Change it, then reset.
First Alert says 1 chirp about once a minute is the low-battery chirp. A battery facing the wrong way, a drawer not fully shut, the pull-tab left in or a rechargeable can all cause it.
- Fit a fresh battery of the type your manual lists. No rechargeables.
- Then reset it: power off at the fuse box if it’s a mains alarm, take it off its base, unplug it if it has a plug, battery out, hold the test button for at least 15 seconds, battery back in, plug back in, refit it and power on.
- Press test once so it checks the new battery.
Check your model’s manual
2 chirps isn’t a code we found for First Alert in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
A fault. Power it off, clean it, test it.
First Alert says 3 chirps about once a minute is its malfunction chirp.
- On a mains alarm, switch it off at the breaker for 1 minute, then back on.
- Vacuum round the slots and press test.
- Check the date on the back. If it’s expired, or the chirps carry on, replace it. Under warranty? Contact First Alert.
Check your model’s manual
4 chirps isn’t a code we found for First Alert in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
End of life. Replace the alarm.
First Alert says 5 chirps about once a minute is the end-of-life chirp. Its support page says you can hush it for about 2 days at a time and that after 2 to 3 weeks it can’t be silenced; some models, such as the SM310, hush for about 8 hours. On a brand-new alarm, 5 chirps can mean the backup battery isn’t switched on: twist it firmly onto its bracket and check any switch on the back isn’t set to off.
- Replace the whole alarm. A new battery won’t stop this warning.
- Check the date on the back or side, and replace any other alarms of the same age.
- Renting? Tell your landlord: in England most landlords must repair or replace a faulty alarm you report.
Get out now
A loud alarm that keeps going isn’t a chirp: it’s warning you about smoke, heat or carbon monoxide.
- Get everyone out and stay out.
- Call 999 in the UK or 911 in the US.
- If it’s a carbon monoxide alarm, get into fresh air. In Great Britain the gas emergency number is 0800 111 999; in Northern Ireland it’s 0800 002 001.
Low battery
On FireAngel’s sealed alarms, such as the ST-622 and FA6620, a chirp every 40 seconds with a red flash is a low battery. The whole alarm needs replacing: FireAngel says straight away for the ST-622 and within 30 days for the FA6620. On the SW1-R and HW1-R mains alarms, a chirp every 32 seconds with a red flash at the same time means change the backup battery; without a flash, it’s a fault.
- Sealed alarm: replace it. The hush button silences the chirp for 8 hours, up to 10 times, to get you through the night.
- Mains alarm with a battery: fit a fresh one of the type in the manual, then reset it and press test.
- If the red light flashes at a different time from the chirp, it’s a fault: contact FireAngel or replace it.
A fault
On FireAngel’s FA6620, two chirps and two flashes every 40 seconds means a fault, and the alarm can’t be silenced while it shows one. FireAngel’s manual says an alarm showing a fault may not warn you of a fire.
- Replace the alarm straight away: FireAngel’s manual says it may not sound in a fire.
- Still under warranty? Contact FireAngel, who can arrange a replacement.
End of life. Replace the alarm.
On the ST-622, three chirps with three red flashes every 40 seconds means the alarm has reached the end of its life.
- Replace the whole alarm. A new battery won’t stop this warning.
- Check the date on the back or side, and replace any other alarms of the same age.
- Renting? Tell your landlord: in England most landlords must repair or replace a faulty alarm you report.
Check your model’s manual
4 chirps isn’t a code we found for FireAngel in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Check your model’s manual
5 chirps isn’t a code we found for FireAngel in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Get out now
A loud alarm that keeps going isn’t a chirp: it’s warning you about smoke, heat or carbon monoxide.
- Get everyone out and stay out.
- Call 999 in the UK or 911 in the US.
- If it’s a carbon monoxide alarm, get into fresh air. In Great Britain the gas emergency number is 0800 111 999; in Northern Ireland it’s 0800 002 001.
Low backup battery. Check the power.
On Aico’s 3000 series mains alarms, one chirp with a yellow flash every 48 seconds means the sealed backup battery is flat, usually because the alarm has lost mains power. On a sealed Ei650, a beep about every 32 seconds with a flash means the alarm needs replacing. Aico’s 140 series has a 9V battery you change.
- Look at the green power light. If it’s off, or flashing every 48 seconds, the alarm isn’t getting mains power.
- Check for a tripped switch at the fuse box. If in doubt, call an electrician.
- Once the power’s back, Aico’s manual says the chirps should stop within 2 hours as it recharges. If they carry on with the green light on, the alarm needs repairing or replacing.
A sensor fault
On Aico’s 3000 series, two chirps with two yellow flashes every 48 seconds means a fault with the sensor. On the Ei650, two beeps every 32 seconds means the smoke chamber is degraded.
- 3000 series: Aico says the alarm must be returned for repair or replacement. It may not detect a fire while it shows a sensor fault.
- Ei650: vacuum the side slots. If it carries on, return it for service (the Ei650i manual says replace it).
End of life. Replace the alarm.
On Aico’s 3000 series, three chirps with three yellow flashes every 48 seconds means the alarm has passed its 10th year.
- Replace the whole alarm. A new battery won’t stop this warning.
- Check the date on the back or side, and replace any other alarms of the same age.
- Renting? Tell your landlord: in England most landlords must repair or replace a faulty alarm you report.
Too much dust
On the Aico Ei3016 and Ei3024, four chirps with four yellow flashes when you press the test button means it has reached its maximum dust compensation. Aico says it still works, but it’s more likely to give false alarms.
- Clean it with the vacuum’s narrow nozzle round the side slots.
- If the alarms went off after dusty work such as new carpets, Aico says to take it off the ceiling for 5 minutes, then refit it in clean air so its dust compensation catches up.
- If it keeps happening, contact Aico or your installer.
Check your model’s manual
5 chirps isn’t a code we found for Aico in the manuals and support pages we checked. Your model’s manual says what it means. NFPA says the label on the back often lists the sounds, or you can search the make and model online.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Get out now
A loud alarm that keeps going isn’t a chirp: it’s warning you about smoke, heat or carbon monoxide.
- Get everyone out and stay out.
- Call 999 in the UK or 911 in the US.
- If it’s a carbon monoxide alarm, get into fresh air. In Great Britain the gas emergency number is 0800 111 999; in Northern Ireland it’s 0800 002 001.
Most likely a low battery
NFPA says a single chirp every 30 or 60 seconds means the battery is low.
- Fit a fresh battery of the type your manual lists. No rechargeables.
- Then reset it: power off at the fuse box if it’s a mains alarm, take it off its base, unplug it if it has a plug, battery out, hold the test button for at least 15 seconds, battery back in, plug back in, refit it and power on.
- Press test once so it checks the new battery.
Check your model’s manual
Codes differ between makers. On First Alert, 3 chirps is a fault and 5 is end of life; on Aico’s 3000 series and FireAngel’s ST-622, 3 chirps is end of life; on Kidde’s 10Y29, 2 chirps is end of life. Without the manual, you can’t tell what 2 chirps means on your alarm.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Check your model’s manual
Codes differ between makers. On First Alert, 3 chirps is a fault and 5 is end of life; on Aico’s 3000 series and FireAngel’s ST-622, 3 chirps is end of life; on Kidde’s 10Y29, 2 chirps is end of life. Without the manual, you can’t tell what 3 chirps means on your alarm.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Check your model’s manual
Codes differ between makers. On First Alert, 3 chirps is a fault and 5 is end of life; on Aico’s 3000 series and FireAngel’s ST-622, 3 chirps is end of life; on Kidde’s 10Y29, 2 chirps is end of life. Without the manual, you can’t tell what 4 chirps means on your alarm.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Check your model’s manual
Codes differ between makers. On First Alert, 3 chirps is a fault and 5 is end of life; on Aico’s 3000 series and FireAngel’s ST-622, 3 chirps is end of life; on Kidde’s 10Y29, 2 chirps is end of life. Without the manual, you can’t tell what 5 chirps means on your alarm.
- Watch the light. On some Kidde and FireAngel alarms, a chirp with the red flash means a low battery, and a chirp between flashes means a fault, but other models differ, so check the manual.
- If it’s more than 10 years old, replace it.
Get out now
A loud alarm that keeps going isn’t a chirp: it’s warning you about smoke, heat or carbon monoxide.
- Get everyone out and stay out.
- Call 999 in the UK or 911 in the US.
- If it’s a carbon monoxide alarm, get into fresh air. In Great Britain the gas emergency number is 0800 111 999; in Northern Ireland it’s 0800 002 001.
Reset it: drain the leftover charge
Kidde says an alarm can remember a weak battery after it’s been changed. This clears it.
- Mains alarm? Switch it off at the fuse box or breaker first.
- Twist the alarm off its base and unplug it if it has a plug.
- Take the battery out, if it comes out. On a sealed 10-year alarm, don’t use the off or deactivation switch: that drains the battery for good.
- Hold the test button for at least 15 seconds. It may sound briefly.
- Battery back in, plug back in, alarm back on its base, power on.
- Press test once. First Alert says an untested alarm can keep reporting a low battery for up to 2 hours.
Give it 10 minutes. Has it stopped?
See this in the guideCheck the battery itself
- Is it the type the manual lists? First Alert and Kidde say no rechargeables, and some Kidde models no lithium.
- Check the date on the pack. Kidde suggests a use-by date four to five years away.
- The right way round, pushed fully in, the drawer or door fully shut, and the pull-tab out.
- Look for corrosion on the contacts. A damaged battery clip or wires means the alarm needs replacing, Aico says.
Fixed that? Press test. Has it stopped?
See this in the guideClean it, and look for draughts and steam
- Vacuum round the slots on the side with the narrow nozzle. Don’t open the case or use cleaners on it.
- Steam from a bathroom or kitchen, or a fan, vent or open window within about a metre, can set off random chirps.
- Chirps only at night? Kidde says cold makes a weak battery struggle, so it’s most likely the battery: try a fresh one from a new pack.
Has it stopped?
See this in the guideTime for a new alarm
- Check the date on the back or side. NFPA and the makers say replace after 10 years at most; Kidde says 7 for combined smoke and CO alarms.
- NFPA says chirping that continues after the battery has been replaced means the alarm is at the end of its life.
- Renting? In England, report it: most landlords must repair or replace it.
- Until then, don’t leave the battery out. Use the hush button if it has one.
Quiet again. Keep it working.
- Test it at least once a month. If it doesn’t sound when you press test, it isn’t working: change the battery or replace the alarm.
- Vacuum the slots when you change the battery.
- Note the replace-by date on the back or side.
Is it a chirp or a real alarm?
A chirp is short and comes back every 30 seconds to a minute or so. It’s the alarm telling you about itself. NFPA says a single chirp every 30 or 60 seconds means the battery is low.
A real alarm is loud and doesn’t stop. On most US alarms it’s three loud beeps, a pause, then three more; many UK alarms sound continuously. If a smoke alarm is going off, get everyone out, stay out and call 999, or 911 in the US.
Check the noise really is the smoke alarm, too. Aico points out that it could be a carbon monoxide alarm, a clock or a washing machine, and First Alert says security systems chirp as well.
Why it still chirps after a new battery
- It remembers the low battery. Kidde says “the alarm’s processor retains error conditions, such as a weak battery, even after the battery is replaced.” The reset below clears it.
- It hasn’t checked the new battery yet. First Alert says an alarm that isn’t tested may keep reporting a low battery until it next checks, from 30 minutes to 2 hours depending on the model. Press the test button after you change the battery.
- The battery isn’t right. The wrong type, a rechargeable, an old battery from the drawer, the wrong way round, not pushed fully in, the drawer or door not fully shut, or the pull-tab still in. First Alert and Kidde list these between them.
- The alarm has reached the end of its life. NFPA says chirping that continues after the battery has been replaced means the alarm is at the end of its life.
- Something else. Dust or insects in the sensor, steam, a draught, or a cold night making a weak battery struggle. See other causes.
Reset it: drain the leftover charge
The four most-watched videos we found all give this fix, and Kidde and First Alert both publish it. It drains the charge left inside so the alarm forgets the old low-battery warning.
- If the alarm is wired to the mains, switch it off at the fuse box (consumer unit) or circuit breaker first.
- Twist the alarm off its base. If it has a plug on the back, unplug it.
- Take the battery out, if it has one that comes out. On a sealed 10-year alarm, don’t use the off or deactivation switch: that drains the battery for good.
- Press and hold the test button for at least 15 seconds. Kidde says it may chirp or sound for a few seconds before going silent. First Alert says 15 to 30 seconds.
- Put the battery back in, plug it back in, refit the alarm and switch the power back on. Kidde says a mains alarm chirps once when the power comes back, then should stop.
- Press the test button once, so it checks the new battery. If it doesn’t sound, GOV.UK says it isn’t working: change the battery, and if that doesn’t help, replace the alarm.
Aico’s 3000 series has no battery to take out. Its manual says holding the test button for at least 20 seconds clears its alarm memory, a different feature from the low-battery warning.
Check the battery
- Use the type your manual lists. First Alert and Kidde both say not to use rechargeable batteries. Some Kidde models also say not to use lithium batteries, while some First Alert models allow a lithium 9V, so go by your own manual.
- Check the date on the pack. Kidde suggests a battery with a use-by date four to five years away. First Alert says batteries kept in cold places, such as a fridge, lose their charge faster.
- Fit it properly. The right way round, pushed fully in, the drawer or door fully shut, and any pull-tab removed.
- Look at the contacts. First Alert lists corrosion on the battery contacts. Aico warns that a damaged battery clip or wires cause constant beeps and mean the alarm needs replacing.
Count the chirps
Makers use the number of chirps, and on many alarms a light, to tell you different things. These are the codes in each maker’s own manual or support pages.
- First Alert (about once a minute): 1 chirp is a low battery, 3 chirps a fault, 5 chirps end of life. For a fault on a mains alarm, First Alert says to switch it off at the breaker for a minute and back on. On First Alert’s sealed SM310, five chirps can also mean a flat battery; either way, replace it.
- Kidde: a low battery chirps every 30 to 40 seconds (every 60 seconds on some models) for at least seven days. On the UK 10Y29 sealed alarm, two chirps every 30 seconds with one flash means end of life. On Kidde’s newer US Detect alarms, three chirps every 60 seconds means a fault, and two chirps means end of life. On some US alarms, a chirp between the red light’s flashes, rather than with them, means a fault.
- FireAngel: on the sealed ST-622, a chirp every 40 seconds is a low battery, and three chirps with three red flashes every 40 seconds is end of life. If the red light flashes at a separate time from the chirp, that’s a fault. The FA6620 gives two chirps and two flashes for a fault. The SW1-R and HW1-R mains alarms chirp every 32 seconds: with a red flash at the same time, change the battery; without one, it’s a fault.
- Aico 3000 series (Ei3016, Ei3014, Ei3024), every 48 seconds with a yellow flash: 1 chirp is a low backup battery, 2 chirps a sensor fault, 3 chirps end of life. Four chirps and four yellow flashes when you press the test button means it has reached its maximum dust compensation.
A fault code means the alarm may not detect a fire, so replace it promptly. Other models use other codes, and a few support pages disagree with the manuals. Your alarm’s own manual wins.
Mains alarms and backup batteries
Mains (hard-wired) alarms chirp too, because of their backup battery. Some take a 9V or AA that you change. Many UK mains alarms, such as Aico’s 3000 and 160e series, have a rechargeable lithium cell sealed inside that lasts the alarm’s life.
On an Aico 3000 series alarm, a single chirp with a yellow flash every 48 seconds means the backup is flat. Aico says to check the green power light: if it’s off, or flashing every 48 seconds, the alarm isn’t getting mains power. Check for a tripped switch at the fuse box, and call an electrician if in doubt. Once the power is back, Aico’s manual says the chirps should stop within 2 hours as the cell recharges. If they carry on for more than 2 hours with the green light on, the alarm needs repairing or replacing.
Sealed 10-year alarms
A sealed alarm has a long-life lithium battery built in, and no battery door. FireAngel’s ST-622 and Kidde’s 10Y29 are examples. When one gives a low-battery chirp, the alarm needs replacing: FireAngel’s manual recommends you replace it immediately. Don’t try to open it or take the battery out; FireAngel says it’s a sealed unit and opening the case invalidates the warranty.
Many sealed alarms let you silence a low-battery chirp overnight. FireAngel’s ST-622 silences it for 8 hours, up to 10 times; Aico’s Ei650i for 12 hours. That buys you a night’s sleep, not a fix.
How old is it?
NFPA, Kidde, FireAngel and Aico all say to replace a smoke alarm after 10 years at most. NFPA says the 10 years count from the date of manufacture, and if there’s no date on the alarm, replace it. Kidde says combined smoke and carbon monoxide alarms should be replaced every 7 years, so go by the replace-by date on yours.
The date is on the back of Kidde and First Alert alarms and on a label on the side of Aico alarms; on FireAngel alarms it varies by model. Aico’s four-digit code is the year then the week it was made, with the replace-by date above it.
Linked alarms: finding the one that’s chirping
A chirp is hard to place on a ceiling. Stand under each alarm in turn and watch its light as it chirps. On Aico’s 3000 series, the one with the problem flashes yellow with each chirp. On an Aico Ei650i system, Aico says to press and hold each alarm’s test button: the faulty one flashes its yellow light rapidly. First Alert’s SA320 flashes its green light to show which alarm needs a new battery.
In a real alarm, every linked alarm sounds, but Aico and FireAngel say only the one that detected the smoke or heat flashes its red light.
Two more linked-set causes: Kidde says a loose neutral wire can make a chirp echo from one alarm to the next, and Aico says RadioLINK alarms that sound for two seconds every four hours have a flat radio module battery somewhere in the system.
Other causes: cold nights, dust, steam and draughts
- Cold nights. Kidde says most homes are coolest between 2am and 6am, and the cold raises a weak battery’s internal resistance, so it may chirp in the night and stop when the house warms up. Kidde’s answer is a fresh battery.
- Dust and insects. Kidde UK says dust in the sensing chamber can cause chirping, and suggests cleaning the alarm with a vacuum when you change the battery. Aico says to use the vacuum’s narrow nozzle on the side slots where the air goes in. Don’t open the case or use solvents or cleaners on it.
- Steam and humidity. Kidde says humidity, steam and condensation can trigger random chirping. FireAngel, Aico and First Alert all say not to fit a smoke alarm in a bathroom or right next to one.
- Draughts. Kidde suggests checking for a heating or cooling vent, ceiling fan or open window within about a metre (three feet).
- The hush button. Kidde says an alarm in hush mode chirps every 30 to 40 seconds for about seven minutes, and First Alert says once a minute for up to 15 minutes.
Never leave the battery out
Taking the battery out stops the noise and leaves you without an alarm. GOV.UK says to take the battery out only when you’re replacing it, and never to disconnect an alarm or take its batteries out if it goes off by mistake. It also says you’re around 8 times more likely to die in a fire if you don’t have a working smoke alarm. The US Fire Administration says a smoke alarm with a dead or missing battery is the same as having no smoke alarm at all. Aico says not to leave an alarm off its base because the beeping is annoying.
If you can’t fix it today, use the hush button if it has one, and replace the battery or the alarm as soon as you can. Test your alarms at least once a month: GOV.UK and NFPA both say so.
The rules
- England, rented homes: most private and social landlords must make sure there’s a smoke alarm on every storey with a room used as living accommodation, and a carbon monoxide alarm in any such room with a fixed combustion appliance, such as a boiler or wood burner (gas cookers don’t count). Lodgers who live with their landlord, leases of 7 years or more, student halls, hostels, refuges, care homes and hospitals aren’t covered. Since 1 October 2022, if a tenant reports an alarm that isn’t working, the landlord must repair or replace it. GOV.UK advises tenants to change the batteries themselves, and to report it if that doesn’t work or they can’t.
- Scotland, every home: since 1 February 2022, every home must have interlinked fire alarms: a smoke alarm in the living room or the room used most, one in every hallway and landing, and a heat alarm in the kitchen, all on the ceiling. Battery alarms must be sealed, tamper-proof units with long-life lithium batteries.
- Wales, rented homes: since 1 December 2022, a mains-powered smoke alarm on each storey, linked to the other mains alarms and kept in working order, and a carbon monoxide alarm in any room with a gas, oil or solid fuel appliance.
- Northern Ireland, private tenancies: interlinked smoke and heat alarms, mains-wired or sealed-battery, a carbon monoxide alarm where there’s a fixed combustion appliance or a flue, and a landlord who replaces an alarm when told it’s faulty and before its expiry date. This has applied to new tenancies since 1 September 2024 and to all other private tenancies since 1 December 2024.
- US: NFPA says to test alarms at least once a month and replace them 10 years after the date of manufacture. Some states go further. Battery-only alarms sold in California since 2014 and in New York since April 2019 must have a sealed battery that lasts at least 10 years, and in Maryland any battery-only alarm that’s allowed must be a sealed unit with a 10-year battery and a hush button. Working alarms you already have don’t need replacing.
Sources
- NFPA: smoke alarms (chirps, end of life, 10 years, monthly test)
- Kidde: intermittent beeping causes (reset, battery, humidity, airflow, loose neutral), night-time chirps, consistent chirping causes, Kidde UK: why does my smoke alarm beep or chirp, and the 10Y29, i12060A and PI9010 user guides
- First Alert: alarm chirps with a new battery, what do the chirps mean, find the chirp, and the 9120B, SA320 and SM310 user manuals
- FireAngel: ST-622, FA6620 and SW1-R/HW1-R manuals, and what does my smoke alarm beeping mean
- Aico: Ei3016, Ei3014 and Ei3024 instructions, Ei160e and Ei650 instructions, homeowner FAQs and product FAQs
- GOV.UK: fire safety in the home and the smoke and carbon monoxide alarm Q&A for landlords and tenants
- Legislation: Smoke and Carbon Monoxide Alarm (England) Regulations 2015, regulation 4 as amended by SI 2022/707; Wales SI 2022/6; Northern Ireland SR 2024/123
- Scottish Government: fire and smoke alarms in Scottish homes
- US Fire Administration: smoke alarms
- California State Fire Marshal: Information Bulletin 14-006; New York Department of State: smoke alarm sales requirements; Maryland Public Safety Article §9-101 and §9-104
- Gas emergency numbers: NHS carbon monoxide poisoning (Great Britain) and Phoenix Natural Gas (Northern Ireland)
Read the video transcript
I put a brand new battery in this. It's still chirping. Every 30 seconds. Why? Usually the alarm still remembers the old battery, the new battery isn't right for it, or the alarm itself has had it. Here's how to tell. First, make sure it's a chirp: a short chirp, or a few, every thirty seconds to a minute. A real alarm is loud and doesn't stop, either one constant sound or repeating bursts of beeps. That means get out, stay out and call 999, or 911 in the US. For a chirp, start with the memory. Kidde says an alarm can hold on to a low-battery error after the battery's changed. So drain it. If it's wired to the mains, switch it off at the fuse box first. Twist the alarm off its base, unplug it if it has a plug, and take the battery out, if it comes out. Then hold the test button down for at least fifteen seconds. It may sound briefly. Fifteen seconds feels longer up a ladder. Battery back in, plug back in, alarm back up, power on, and press test once. Skip the test and some keep reporting low battery for up to two hours. Still chirping? Check the battery. Use the type your manual lists: First Alert and Kidde both say no rechargeables. Kidde suggests a use-by date four to five years away, so the one from the kitchen drawer may not count as new. And check it's the right way round, pushed fully in, with the pull-tab gone. Then count the chirps. On First Alert, one chirp a minute is low battery, three is a fault and five is end of life. Aico's 3000 series mains alarms flash yellow with each set: one for a low backup battery, two for a sensor fault, three for end of life. Those Aico alarms, like many UK mains alarms, have a rechargeable backup sealed inside. If the green power light is off or flashing, look for a tripped switch at the fuse box. Aico says the chirps should stop within two hours of the power coming back. Sealed ten-year alarms, from makers like FireAngel and Kidde, have no battery to change. When one chirps for low battery, it needs replacing. And every maker we checked, and NFPA, says replace any smoke alarm after ten years at most, and combined smoke and CO alarms often sooner. The date is on the back or the side. With linked alarms, a chirp is hard to place. Stand under each one and watch its light as it chirps: on Aico, the one with the problem flashes yellow with each chirp. It's the least relaxing birdwatching there is. Kidde lists a few more causes. Most homes are coolest between two and six in the morning, and cold makes a weak battery struggle, which is why it often starts at night. Dust and insects: vacuum round the slots, but don't open the case. And steam, or a draught from a fan or vent close by. Whatever you do, don't take the battery out and leave it out. GOV.UK says you're around eight times more likely to die in a fire without a working smoke alarm. In England, if you rent and a new battery doesn't fix it, report it: your landlord must repair or replace it. In Scotland, every home has needed interlinked alarms since 2022. In the UK and the US, test yours at least once a month. Our guide has a chirp decoder: pick your make and what you can hear, and it tells you what to do. That's HanaHow.
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