CALL OUR TEAM NOW 0800 612 6537 Lines open today 8:30am - 12:30pm

How to stop beeping from Ei / Aico mains powered smoke and heat alarms

Ei141, Ei144, Ei146, Ei150, Ei151, Ei154, Ei156, Ei161, Ei164, Ei166

Here are some common questions we have been asked by our customers about Ei Electronics and Aico (Ei’s UK operation) mains powered smoke alarms and heat alarms through our fire safety forum.

You may find this range of videos, showing how to change batteries and detector heads, useful. We also offer replacement smoke detector heads so that you can change your alarm without the need to call in an electrician.

General smoke alarm problems

For our general smoke alarm troubleshooting guide, please also see our most recent guide:


Smoke alarm is false alarming

The most common source of false alarms in smoke detectors is contamination (such as dust and small insects) within the sensor chamber. Cleaning the unit by either vacuuming around the central detection chamber or blowing it out with the cold setting on a hair dryer normally resolves this issue.

Another reason for false alarms could be down to the age of the unit. Smoke and heat alarms are designed to last for around ten years, after which it is recommended that they are replaced as the sensors start to deteriorate and are no longer as effective. There should be a 'replace by' sticker on the side or reverse of the alarm.

For most Ei Electronics mains powered smoke alarms, a replacement kit is available containing a compatible smoke alarm, and in the case of Ei140 and Ei160 alarms, the new head just slides onto the existing base without the need for an electrician.

Ei Electronics and Aico products have usually a 5 year manufacturer’s warranty during which they will be repaired or replaced free of charge if suffering from faults or defects caused by manufacturing issues. Aico’s telephone number is 01691 664100. They deal with warranty cases for the mains powered ranges.

Smoke alarm starts to beep in the middle of the night

Beeping or chirping is normally due to low battery power in the alarm. This beeping most commonly starts at night due to the drop in temperature causing a decrease in battery power.

If the unit has a replaceable battery (Ei140 series) this problem is normally resolved by replacing the alkaline back-up battery. Ei Electronics only recommend using either EverReady 522 or Duracell MN1604 batteries.

If the alarm continues to beep or if the unit has a sealed battery (Ei150 and Ei160 series), check the manufacturing date. Alarms are designed to last for around ten years and if the alarm is significantly older than this, the beeps might be a warning that the electronics inside are ageing or that the lithium battery is at the end of its life.

For most Ei Electronics mains powered alarms a replacement kit is available - this contains an original Ei replacement alarm which is compatible with the old system and contains instructions on how to install.

If a smoke alarm with sealed back-up battery is not out-of-date, shows the green light and still beeps occasionally, press the test button for more than 10 seconds to reset the alarm. If this does not help then you will need to replace your detector head.

The beeping may actually be coming from a different alarm, such as a carbon monoxide detector with a low battery. Always check that other nearby alarms are not the source of the beeping.

Mains smoke alarm beeping randomly throughout the day

If a mains powered smoke alarm gives an irregular warning sound, it could indicate that the mains power supply is interrupted. Ei electronic alarms have a green LED light on the outer case to show that the smoke alarm is connected to the mains power. If the green LED is not lit it can be an indication that there has been an interruption in the mains power supply and that the alarm will be using the back-up battery as the sole power source.

Interruptions of the mains power can be due to several reasons, including incorrect wiring (e.g. if the power supply comes from the lighting system and the alarm is incorrectly wired to the switched part of the circuit or when neutral/earth wiring are reversed), tripped fuses/circuit breakers, loose wires and general power failure. Electrical spikes can also cause false alarms or damage the smoke alarms.

Smoke detector is off the ceiling and the battery has been removed but the beeping continues

If a smoke detector is removed from the base and the battery is also removed, the alarm might still hold some residual charge and beep for up to a minute. Pressing the test button for about 10 seconds will discharge the circuitry.

If the alarm has a sealed lithium back-up battery, the battery is automatically disconnected as soon as the alarm is removed from the base. As with the alkaline battery units, the alarm might still hold some residual charge and beep for up to a minute. Pressing the test button for about 10 seconds will discharge the circuitry.

If you still hear beeping, this sound does NOT come from the smoke alarm! There is no sounder within the base of an Ei/Aico mains powered heat or smoke alarms, so if the beeping continues it is coming from a different alarm, e.g. a CO alarm somewhere close by. You will need to find the source of the beeping alarm to stop the nuisance. It is really difficult to find the source of a beeping CO alarm, sometimes the CO alarms are even hidden in drawers!

How can I isolate and turn off my mains powered smoke alarms to change the back-up battery without having to reset my oven or other appliances?

Mains powered alarms will be powered either by a dedicated power spur or by the lighting circuit. The oven will be on an entirely separate spur. When changing the battery in a smoke alarm, only flick off the fuse that relates to the smoke alarms, not the power supply to the entire house. The fuse for the alarms should have been marked by the electrician with a sticker that comes with each Ei alarm. If that is missing try each fuse until you have found the one that switches off the smoke alarms and then mark it with a sticker or pen. You will know when you have located the correct fuse as the green LED on each smoke alarm will turn off.

How can radio-interlinked smoke alarms be silenced?

In an interlinked system when one unit detects smoke, all alarms sound. To silence the alarms in case of a false alarm, press the hush button on the unit that has detected the smoke. This will silence all interlinked alarms.

If the detector which caused the alarm is not known, it can usually be identified as the unit with a rapidly flashing red LED light on the unit.

Customer-specific case studies

Scenario: Beeping of Ei151TL after electricity was turned off

The electricity was off for a while and since it has been switched back on the alarms beep every few minutes. It was initially assumed it was because it was recharging but it went on for days.

The green light, indicating that the alarm is connected to the mains, glows constantly.


Remove the alarm from its base and press the test button to drain the residual charge. Does the beeping stop? If not, you have a different alarm in the room that is beeping, e.g. a CO alarm with a low battery

If the beeping does stop it indicates that the alarm is older than 10 years or has a fault. In both cases it needs to be replaced. If your alarm is outside of the 5 year warranty period, you will need to purchase a new smoke alarm; if it is within the warranty period you can contact Aico for a free replacement alarm under the warranty. As the Ei150 series is not manufactured any longer you will need to use compatible replacement smoke alarms.

Additional information:

The 151TL will emit this type of beep for one of three reasons:

  1. Mains power was lost and the back-up battery has run down. Once the mains power is restored the battery will recharge and the beeping will eventually stop.
  2. The unit is in "hush" mode, these beeps will self-cancel after ten minutes just by doing nothing.
  3. The unit is failing because it is over ten years old or faulty.

Note: This scenario is also applicable to other Ei150 and the Ei160 series alarms. The Ei150 and Ei160 ranges are smoke alarms with sealed-in, rechargeable backup batteries.

Scenario: Newly installed Ei161 randomly emits short beeping sounds

A new Ei161 alarm has been installed but is randomly emitting short (1-2 seconds) alarm beeping sounds.


The first thing to check in this scenario is whether the mains power is on by checking that the green LED on the alarm is lit. If the power supply is directly from the fuse box, make sure the fuse has been switched on again after the smoke alarm replacement or installation.

Another potential reason for this beeping in new installations is if the alarm is powered by a lighting circuit (quite common) but has been wired incorrectly and the power supply is interrupted by a light switch. To check if this is the case the green light should be monitored to check it is on at all times indicating a constant power supply. If the green light is interrupted you will need to call your electrician to review the installation and correct the installation fault.

Note: This scenario is also applicable to other Ei/Aico mains powered alarms.

Scenario: Ei168 RF base has a flashing amber light

One of the Ei168 radio bases flashes amber light every 10 seconds. All other bases in the group are fine.


The amber light may flash for one of two reasons; firstly it may be indicating the base is in House Code mode (used while setting up new networks of radio-interlinked alarms). House Code mode is automatically exited after 30 minutes or can be manually exited by inserting a screwdriver in the House Code slot and holding the House Code switch until the amber light turns on. Once a solid amber light appears release the switch and the amber light should stop flashing.

Ei168 RF base plate showing location of the House Code slot

Ei168 RF base plate showing location of the House Code slot

Another reason the amber light may be flashing is to indicate that the rechargeable back-up battery of the radio-base Ei168 is running low or not re-charging properly.

First thing to check is that the internal 'Battery on' switch is properly triggered. Remove the smoke alarm with the help of a screwdriver and press the 'on' switch on the base plate. Now replace the alarm.

Location of ON/Off switch on Ei168 base plate

Location of ON/Off switch on Ei168 base plate

If that does not resolve the issue, check that the power supply is not from a switched power source. This can occur if the unit has been incorrectly installed from the nearest lighting circuit. Switch the light from which the smoke alarm is fed with power, on and leave it on for 24 hours; if the amber light stops, call out the electrician to check wiring.

Scenario: Ei175 smoke alarm system for the deaf and hard of hearing has an inconsistent green mains power light

An Ei175 smoke alarm system for the deaf and hard of hearing has an inconsistent green mains power light. Sometimes the light will be on but other times off and sometimes even flashing.


A problem such as this could be caused by a loose connection if the 3 pin plug has been changed.

Try the system in a different plug socket in the house to see if the problem stops, this will eliminate the possibility that the socket could be causing the problem. If this does not resolve the issue check the warranty on your deaf alarm and contact Aico.

Scenario: Ei170RF Deaf smoke alarm not going off when testing

The Ei170RF radio-interlinked strobe and vibration pad set is not going off when the interconnected smoke alarms are tested.


The first thing to check in this case is that the unit is in the same house code system as all of your alarms. This can be done by re-house coding all of your alarms as described in the product’s instruction manual.

The green mains power indicator at the top left side of the unit should be constantly on. If it is off check that it is plugged into the mains, that the socket is not switched off and fuses, circuit breakers etc. are still functioning.

Another reason for this issue to occur would be if the vibration pad is not plugged into the strobe. The pad and strobe both need to be connected for the strobe to go off.

Scenario: Ei140 radio-interlinked alarms not interconnecting

The radio interlinked smoke alarms of the Ei140 series alarms, while having been fitted by an electrician, are not interconnecting.


It would appear that the system has been house coded incorrectly or something is disturbing the signal. If the units have not yet been house coded, the instructions supplied with the unit should be followed to do this. In most situations this will resolve the problem.

If the units have already been house coded or are still causing problems after house coding they may need to be reset back to factory mode. To set units back to factory mode: insert a screwdriver into the house code slot for seven seconds until the amber light has come on fully and repeat with other units. You can then repeat the house coding routine.

If this still fails to resolve the issue the interconnection distance may need to be reviewed. If the distance between alarms is too great or there are very thick walls, the RF signal might not be received by some of the alarms.

Make sure you look after your smoke alarms by changing batteries and testing the unit on a regular basis. We offer free reminder services to ensure you remember to do your alarm test and to change the battery.

You may also find our blog on false alarms interesting.


Reviewed: 13/01/2022 (doc:46 V2.1). Our articles are reviewed regularly. However, any changes made to standards or legislation following the review date will not have been considered. Please note that we provide abridged, easy-to-understand guidance. To make detailed decisions about your fire safety provisions, you might require further advice or need to consult the full standards and legislation.


Colour Scheme


Pricing Display



By continuing to browse this site you agree to the use of cookies.