What causes “chirping” and false alarms in smoke alarms?

hoovering-alarmIf your smoke or heat alarm has started its low battery “chirp” in the middle of the night or alarmed falsely with no obvious reason, unfortunately, many people lose faith in their alarms, seeing them as an annoyance rather than essential life saving devices.
False alarms and chirping are often pointing at problems that require attention. There are a number of checks that can be done to help find the cause before seeking further help from the manufacturer or retailer. Below is a step-by-step guide to the possible causes and solutions for false alarms and chirping; however, always refer to the manufacturer’s instructions for your exact smoke or heat alarm model. Additional care should be taken with mains powered alarms, as interference with the alarm can cause electrocution.

1) “Correct” alarm for the “correct” area
There are three main types of domestic alarms available on the market:

Ionisation Smoke Alarms – Slightly quicker at detecting fast flaming fires than other technologies but usually only installed in upstairs landing areas. If installed near a kitchen, where the occasional toast might get burned, ionisation alarms can cause false alarms. The installation of this alarm near sources of smoke is one of the key reasons for false alarms in daytime.

Optical Smoke Alarms – Slightly quicker at detecting slow smouldering fires that can originate from upholstery type materials and over-heated wiring. Suitable to be installed in bedrooms, living rooms and downstairs hallways. These are fairly ‘toast-proof’ and can be installed near kitchens (not in kitchens, though).

Heat Alarms – Activate when the temperature inside the room reaches a certain trigger level or if the heat in a room rises very quickly. These are ideal in kitchens and garages, as they do not get triggered by fumes. Please note that a heat alarm only covers a small area, so larger kitchens will require several heat alarms.

All types of alarm will sound in the event of a fire; however, understanding more about each sensor technology helps you to select units that are least likely to cause false alarms. Alarms placed in the wrong location will on the other hand cause false alarms, eg if you have a smoke alarm located in the hallway and this sounds each time you use the toaster or boil vegetables, it is likely that you have an ionisation smoke alarm installed rather than an optical.

2) Optimum position
The user manual for your smoke or heat alarm will provide advice on “locations to avoid” when positioning your alarm on the ceiling. Below are some examples:
– Near fluorescent lights – as electronic “noise” can cause false alarms
– In front of air supply ducts for heating or air conditioning, or near ceiling fans
– Directly above cookers/toasters/kettles (heat alarm) – although heat alarms are designed not to cause false alarms from cooking fumes, they should not be installed directly above cooking appliances
– Within 0.9m (3ft) of the door to a bathroom or shower room (smoke alarm) – steam can cause false alarms

3) Dust and/or Insects
Smoke alarms contain a sensor which is used to detect a fire. Over time, dust can build up or small insects/flies can crawl inside the unit, obstruct the sensor and eventually cause false alarms. Cleaning your alarm helps to remove anything that could be blocking the sensor. Wipe the outside of the alarm with a damp cloth, then using a vacuum nozzle or a hair dryer (set on cold), to suck or blow through the openings of the alarm.

4) Decorating
If decorating, especially sanding, has recently taken place, dust particles or paint fumes could have entered the sensor chamber, causing damage to the unit and therefore causing false alarms. It is recommended to temporarily cover the alarm whilst decorating. Some alarms are supplied with a protective cover, so keep hold of this after installation for any future use. If you suspect decorating may have affected your alarm, try cleaning the unit as described above.

5) Temperature
Smoke alarms have an optimum operating temperature and it is important to ensure that your alarm is not subjected to temperatures above or below these thresholds. Typically, the operating temperature for a smoke alarm is between 0 ˚C to +40 ˚C. If the alarm is positioned where it may experience blasts of hot or cold air e.g. close to a front door, or the ambient room temperature is not constant e.g. in attics, this is when false alarms can occur. It may be necessary to reposition your alarm.

6) Age of the alarm
Each smoke and heat alarm should have a sticker located on the edge or the back of the unit indicating a replace-by date. This is usually ten years after manufacture. If your alarm starts chirping or regularly sounds falsely, it could mean that the alarm is close to, or has reached the end of its life. Check the date to see if the alarm is due to be replaced.

7) Problem with the mains supply?
Mains powered smoke alarms can usually be identified by two LEDs located on the face of the unit. One LED flashes red approximately once a minute to indicate that the unit is operating correctly. The second LED should be constantly green to indicate that mains power is present. If the green LED is not present, this could mean that there is an issue with the mains power getting to the alarm. If needed, advice should be obtained by a qualified electrician.

8) Battery running low
Chirping every 30-40 seconds is generally an indication that the battery is running low. If your smoke or heat alarm has a replaceable battery, try changing the battery for a brandnew one. It is recommended to change the batteries in your smoke and heat alarms every 12 months. Changing your battery before it runs low helps to overcome the annoying chirps at night. Change the batteries when the clocks are changed forward or register for a free email reminder service.

Many smoke and heat alarms are now fitted with a sealed lithium battery, designed to last the life of the alarm. These batteries are not accessible for replacement and so if your alarm starts chirping but has a non-replaceable battery, the alarm may have reached the end of its life. Batteries running low apply to both solely battery powered alarms as well as mains powered units with a back-up battery.

9) Another alarm nearby?
If you have tried all the above and you can still hear chirping, the final check is to see if there is another alarm or device within the same area that could be causing the chirp. It is easy to associate chirping with smoke and heat alarms and forget that other devices e.g. carbon monoxide detectors could also contain a battery that is running low.

Safelincs are happy to provide information regarding your smoke and heat alarms. For more information, you can also visit our Smoke Alarm Help Guides page, or contact our customer services team.

Smoke alarms that beep in the night – a new help guide

Ei156TLH Mains Powered Optical Smoke AlarmMains powered smoke alarms are required whenever a new home is built, a home is extended or materially altered. As they are interlinked they ensure that the alarm is spread through the entire building, notifying you of the fire even when you are in bed. Most mains powered alarms have a back-up battery inside to ensure that the alarms work even if their power supply is interrupted, for example by a blown fuse, which can happen when the fire was started by an electrical fault. Over the years, should either the power supply fail or should the backup battery become flat, the alarms will beep to notify you that there is a problem. As the cold of a night will weaken the backup battery, the warning beeps will usually start at night, which is, of course, a nuisance. However, beeping due to low battery is not the only reason an alarm might beep for and it can be very difficult to work out what has gone wrong. To help our customers, we have therefore created a simple-to-follow help guide for one manufacturer’s products. The reason for picking Ei Electronics’ products is that they are the undisputed market leader in mains powered alarms. Their smoke alarms are found in almost every new or converted home in the UK, so that we focused on their products in this help guide.

Their mains powered smoke alarm series is ‘Aico’ branded and follows the following numbering system

Ei140 series (mains powered with alkaline backup battery which needs changing every year or two)

Ei160 series (mains powered with sealed-in, rechargeable 10 year lithium battery

 

Within each series, there are three types of detectors ending each with one of the following numbers:

..1 (eg Ei141): Ionisation smoke alarms. Good for fast flaming fires, such as paper and wood. They do, however, have a tendency to false alarm if for example a toast is burned nearby.

..4 (eg Ei144): Heat alarms. Used in kitchens, as these units are insensitive to burnt toast

..6 (eg Ei146): Optical smoke alarms. Less prone to false alarms from burnt toast. Good for smouldering fires such as from soft furnishing

Further helpful information about smoke alarms can be found in our help section.

Replacement smoke alarms can be easily identified on our overview chart showing older smoke alarms models and their replacements.

For Aico/Ei Electronics mains powered smoke alarms we are able to offer dedicated replacement alarms that can be fitted by a home owner without requiring an electrician.

We also offer very detailed further advise about smoke alarm defects and solutions on our forum.

There is also a range of videos showing you step-by-spep how to remove smoke alarms from their bases

Kidde stops smoke alarms beeping at night

Kidde Safety EuropeSmoke alarms have reduced the number of deaths and injuries related to fire in the UK dramatically over the last decades and are now an essential must-have in every household.
All these millions of smoke alarms, however, rely on batteries in one way or the other. Mains powered smoke alarms require a backup battery in case the mains power supply fails and battery powered smoke alarms use them, as the name suggests, as main source of power. When the battery comes to the end of its life the smoke alarm emits a regular beeping sound for several weeks before the battery finally expires. This gives the owner sufficient time to replace the battery.
As the voltage of a battery drops at lower temperatures, the first low battery warnings are usually emitted at night, when our houses are at the coolest, especially in autumn and winter. This can be very annoying as you are woken up in the middle of the night by a beep every 30 seconds. What can you do to avoid this? You should, of course, replace the batteries regularly before they are getting close to their expiry time and you should have spare batteries at home. However, when it comes to sealed longlife battery units, which last ten years. This situation is much harder to prepare for, as you cannot realistically have a set of complete smoke alarms in your drawer, just in case.
Kidde Fire Safety Products have come up with a brilliant concept to resolve this age old problem. Their longlife, sealed optical smoke alarm 10y29, which has a ten year lifespan, will detect the gradual weakening of its battery and then ensure that the alarm only starts beeping during daytime. This is achieved by monitoring the strengthening/weakening pattern of the battery voltage over a period of time as temperatures rise and fall during the day and nigh time. From this patterns the onboard chip of the smoke alarm will then define the day period and will only then raise the low battery alert during this time. An ingenious solution to a long standing problem.

Fig 1. Normal operation (showing the increasing and decreasing voltage pattern during daytime and night time)

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Fig 2. Dropping voltage and the response of traditional smoke alarms which start beeping in the night

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Fig 3. Kidde’s 10y29 smoke alarm, which records the night time lows but only starts beeping in the daytime

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