

Smoke, Fire & Gas Detection FAQs

Why is my alarm beeping?

In general there are three reasons an alarm might beep, other than when a fire is detected. It could indicate the alarm is over 10 years old and needs replacing. You can find the replace-by date on the alarm itself. Sometimes dust build-up can also set optical smoke alarms off. If this is the case, use a vacuum or hair dryer on the cold setting to clean it. Finally it could be an issue with the power supply. If it is a battery operated alarm, the battery might need replacing. If it is a mains powered alarm there could be a problem with the supply of power to the alarm.

How long do smoke alarms last before needing replacement?




Why do your mains powered alarms have batteries?




What is the best way to test my alarm?


Is there a combination smoke alarm which will detect both a fire and carbon monoxide?

The Kidde 900-0122 and the Kidde 10DS alarms detect both carbon monoxide and smoke.

What is the best way to dispose of an old smoke alarm?

Safelincs has signed up to Valpak's WEEE (Waste Electrical and Electronic Equipment) Distributor Take-Back Scheme*. This means if you are a Safelincs customer you can take old smoke and heat alarms to your local recycling centre.

To find your nearest recycling centre, please visit Find out more about smoke alarm disposal.

*Registration ID: 7370

Can air purifiers affect ionisation smoke alarms?


How do I fit my smoke alarm to the ceiling?

Smoke alarms can be either screwed to the ceiling using the holes on the base plate (screws provided) or fixed using a sticky pad.

Do you need an electrician to connect mains powered smoke alarms?

It is necessary that an electrician installs mains powered smoke alarms.

How long do the batteries last in smoke alarms?



Do I need an ionisation or optical smoke alarm?


I run a bed and breakfast, so I don't want my smoke alarms to beep when the battery runs low, but I also don't want to replace them yearly if they are still charged. Are there any alternatives?

Change the alarms for long life, lithium battery powered alarm, which last 10 years. These are also available as radio-interlinked alarms. Alternatively you can install mains powered alarms.

I need to install a number of alarms to an existing panel mains system, but don't want to install new wires everywhere. Can I install wireless units that will link to the panel system?

You can install mains powered radio-interlinked alarms in the rooms and a mains powered alarm with an Ei128R base near the central control panel. The Ei128R base would then be connected with wire to the panel.

Are there any restrictions to the distance a radio-interlinked smoke alarm will work?

Most radio-interlinked alarms have a range of 150 meters in an open space and up to 30 meters in buildings. The thickness of the walls and partitions will affect the travel distance of the signal.

Which interconnecting smoke alarms would be suitable to connect an upstairs landing, downstairs hallway and a kitchen?

The Ei 140 series with radio-interlink bases would be suitable for this application: Ei168RC/141 ionisation: best for landings Ei168RC/146 optical: best for hallway, living rooms etc Ei168RC/144 heat detector: best for kitchen and garage Alternatively the Ei160 series (again with radio-interlink bases): Ei168RC/161RC ionisation: best for landings Ei168RC/166RC optical: best for hallway, living rooms etc Ei168RC/164RC heat detector: best for kitchen and garage There are also battery operated radio-interlinked smoke alarms available (See Ei3100RF and Ei600RF series)

Can the sound level of smoke alarms be increased if they are used for hard of hearing?

Unfortunately the sound level on a smoke alarm cannot be adjusted.

Do batteries in radio-interlinked alarms expire quicker than those in normal alarms?

Batteries in radio-interlinked alarms do expire quicker than in other smoke alarms. RF smoke alarms are, however, also available with a 10 year sealed long life lithium battery. This battery will last for the 10 year life of the smoke alarm.

Are the battery radio-interlinked smoke alarms suitable to install in a four storey house with thick walls?

Our radio-interlinked smoke detectors have a radio frequency range of about 30 meters in buildings. This means that as long as the detectors are all within 30 meters of each other, the interconnection should be achieved. Some of the RF smoke alarms can also act as repeaters, which means that larger distances can be achieved. So, a four storey house should normally be suitable for RF install.

Is there a radio-interlinking alarm system that will cover a large three storey house? If one is activated they all need to go off.

Our radio-interlinked alarms are designed to have 12 smoke alarm units interlinked with each other in any one series. However the alarms are able to recognise more than 11 other smoke alarms but there will just be no visual confirmation on each unit when going through the initial house coding procedure. Interlinking 12 alarms with 6 call points should work together providing each unit is no more than a 30m distance apart. Larger distances can be covered by using one of the smoke alarms in repeater mode, activated by flicking a switch.

When the test button is pressed on an interlinking smoke alarm will this cause all the other units to go off, too?

Yes, by pressing the test button on one alarm all the units in that family will also be activated. To 'teach' the units which other smoke alarms belong to the same family, the smoke alarms have to be set up together during the installation. This is done by pressing a 'housecoding button' or similar process.

If a false alarm goes off can pressing the hush button on any of the interlinking alarms stop all the units beeping?

No, to stop the alarms from sounding the hush button on the unit that started the process needs to be pushed. Pressing any other unit will just silence that one unit. The unit can be identified by the rapidly flashing red LED.

Can a wireless router interfere with the radio interlinked alarms?

A wireless router is very unlikely to interfere with the signal of your radio interlinked alarms, as the RF signal of the smoke alarms is digitally coded.



I live in a thatched property and want to renew all my fire alarms, both the ones I put in the attic next to the thatch and the ones I put in my home. Is it better to get heat alarms or smoke alarms?

There are three different types of alarms available - ionisation and optical smoke alarms and the heat alarm. The heat alarm is specifically designed for kitchen areas. This is because it is activated when the temperature reaches approx 57 degrees centigrade.

In terms of the two smoke alarms, there is no right or wrong which to install as they are both going to detect a fire. The difference between the two is that ionisation smoke alarms are slightly quicker at detecting fast flaming fires that can cover a small area quite quickly. It is generally recommended for these to be installed in landing areas. Optical smoke alarms are slightly quicker at detecting slow smoldering fires. These originate from upholstery type materials or over heated wiring. These are usually installed in bedrooms, living rooms and downstairs hallways.

In terms of the thatched area, it is usually recommended for an ionisation smoke alarm to be installed in the loft. This is because if the thatch caught alight, it is likely that the thatch would catch fire quickly. With any alarm installed in a loft area, we would recommend that the alarm is cleaned regularly. This is to try and avoid false alarms from happening.

Which smoke alarm has a relay contact to connect to a GSM dialer?

There are two main options:

  • For mains powered, any Ei140 or 160 series alarm can be mounted on an Ei128R or Ei128RBU relay base. This will then give a switched output from the volt-free relay contacts whenever the alarm is triggered.
  • For low-voltage, the Ei100R, 105R, Ei181, Ei186 can be used. All of these units have a built-in set of volt-free relay contacts to again give a switched output.

How do radio interlinked smoke alarms work?

Several RF smoke alarms form a group which has the ability to recognise each other's signals. If one of these alarms detects fire, it sends a digitally coded signal to the other alarms which then also sound an alarm. Radio-interlinked smoke alarms are used in larger houses, small commercial premises and wherever there is a risk that not everybody in the building will hear a fire alarm from a different part of the building.

Which alarms can be interlinked?

All mains powered smoke alarms can be interlinked with signal wire. However, we also offer mains powered AICO/Ei and Kidde Slick alarms with radio-interlink. This saves the connection cable between the units.

In addition we offer battery powered radio-interlinked smoke alarms. A sealed battery operated with ten year battery life is also available.

Do I have to wire mains powered RF alarms at all?

Yes, each mains powered smoke alarm has to be supplied with mains power. In retrofit situations, this power supply will usually be taken from the nearest light fitting. In new builds the electrician will create a dedicated electrical circuit for the alarms. Normal mains powered alarms require also a signal cable between the smoke alarms. Where radio-interlinked mains powered units are used no signal wire between the alarms is required.

How can the alarms interconnect without a cable connection?

Radio-interlinked smoke alarms replace the signal cable between alarms with RF communication. A radio signal is sent when the test button is pressed, or the alarm senses smoke. This is received by all the interlinked alarms in the system and will cause all alarms to sound.

Is there any method of controlling an interlink system?

All our RF alarms offer a range of accessories, such as Manual Call Points. Ei and Aico RF units also offer manual fobs and wall switches to test or silence the system.

Why is carbon monoxide dangerous?

Having no colour, smell or taste means that it is very hard to detect. Inhaling carbon monoxide reduces the blood's ability to carry oxygen, leaving the body's organs and cells starved of oxygen. Each year, over 50 people die in the UK as a direct result of exposure to Carbon Monoxide Gas (CO). Many more people die through strokes and respiratory illness made worse by inhaling low levels of CO over prolonged periods. More, still are left with permanent damage and invalidity.

How can I protect my family from CO poisoning?

Make sure rooms and heaters are well ventilated, have your chimneys and flues checked regularly, make sure boilers and heaters are maintained and serviced regularly. Buy a carbon monoxide alarm/detector. A carbon monoxide alarm will measure the concentration of carbon monoxide in a room and sound an alarm if the CO concentration is higher than permitted



Is there a carbon monoxide alarm for the hearing impaired?

Yes, we supply a strobe and vibration pad for the deaf and hard of hearing, Ei170RF, which can be linked to a mains powered carbon monoxide alarm, Ei262.

Which areas should I avoid installing carbon monoxide detectors?

Do not install CO alarms above or below windows.


For more information please watch our video guide.

What is carbon monoxide?



Why is my mains powered smoke alarm beeping just after it has been installed?

This depends on whether the alarm is sounding intermittently or continuously.

If the alarm is sounding continuously, check there is no smoke or fire in your property.

If the alarm is beeping intermittently, the lithium backup battery may have lost some of its charge in storage resulting in a low battery warning. This will fully recharge within a few hours after the alarm is connected to the mains.

Read our smoke alarm troubleshooting guide to find a full list of reasons and solutions.

Which smoke alarm should I use in a bedroom with an en suite bathroom?

We recommend installing an optical smoke alarm in a bedroom with an en suite bathroom.

It would be less likely to sound a false alarm if steam or water droplets were to come into contact with the smoke alarm. They are also slightly quicker at detecting slow smouldering fires that can originate from upholstery and over-heated wiring. 

Detectors should usually be installed as central to the room as possible. However, we recommend ensuring your detector is not installed directly in the path of the bathroom door as smoke alarms are not designed for use in bathroom areas.

How many alarms can be wirelessly interconnected using radio frequency?

This depends purely on the model and manufacturer of the alarm or system you are planning to install. Some models will allow 12 to 15 alarms to connect wirelessly, whereas other newer models can interlink with up to 50 other devices.

Please view our range of Radio-Interlinked Alarm Systems.

How can I make sure I hear the smoke alarm?

To ensure you hear the smoke alarm when it detects a fire you should have radio-interlinked alarms. If one of the alarms detect a fire then all the other alarms in the system will sound which will greatly increase the chance of the occupant hearing the alarm.

If the occupant has a hearing impairment there are fire detection systems for the deaf and hard of hearing that feature strobe lights and vibration pads to ensure the occupant will be alerted in the event of a fire.

How can I test my heat alarm?

All of our heat alarms have test buttons. Press the test button for about 5 seconds regularly to ensure your alarms are operating correctly.

If you wish to test the heat sensor of the alarm, our advice is to use a solo 400 series tester or call a fire alarm servicing company.

Where should I install carbon monoxide detectors?


Place the detector 1 to 3 meters away from the boiler, etc. to avoid small start-up CO discharges to cause false alarms.

It is advisable to install detectors in areas of your home that you spend the most time in such as the living room and bedrooms. Larger homes may require several detectors to cover the property fully.

Please note: we recommend referring to the manufacturer installation guide that came with your detector for full instructions.

What are the symptoms of carbon monoxide poisoning?


View more symptoms on our carbon monoxide information page.

Can smoke alarms detect carbon monoxide gas?


How do I interconnect compatible alarms that are 'interconnectable'?

Generally, the process for interlinking hardwired alarms is the same. Firstly, you need to make sure that the alarms you are purchasing are compatible with each other, as alarms from different manufacturers (in most cases) do not mix. Dependent on the manufacturer's instructions, you will then be advised to use either a length of bell wire / twin cable to serve as an interlink cable, or 3-core and earth (which is usually adopted in newer installations).

In the same way as interlinking hardwired alarms, it is still crucial to check compatibility between alarms for systems that link wirelessly. The way in which radio-interlinked alarms are connected can differ from brand to brand, however there will be instructions included with the alarm to guide you through the interlinking process. No signal cables are required between radio-interlinked alarms.
