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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?

It is recommended that smoke alarms are replaced after 10 years. This is because the sensors in the smoke alarms become less sensitive and may not activate when a fire is present.

What is the difference between an ionisation and an optical (photoelectrical) smoke alarm?

Ionisation smoke alarms detect fast flaming fires and are suitable for landings. Optical smoke alarms detect slow smouldering fires typical for burning soft furnishings. Optical alarms are suitable for living rooms and sleeping areas and are used near kitchens as they are less prone to false alarms. Please note that ionisation alarms contain a small amount of radioactivity.

Why do your mains powered alarms have batteries?

All our mains powered alarms have a battery backup. Although mains powered alarms without this option do exist (BS5839 part 6 grade E), we regard them as far too dangerous, as a lot of fires are caused by electrical faults leaving the building unprotected against fire if the smoke alarms have no backup battery. With our mains powered alarms you will always be protected.

Can I put my smoke alarm on the wall, or must it be mounted on the ceiling?

The best location to install your smoke alarm is in the centre of the ceiling rather than on the wall. During a fire, smoke initially rises and then spreads to the sides of the room. By installing the alarm on the ceiling, this ensures that you receive the earliest possible warning of a fire.

What is the best way to test my alarm?

We recommend testing alarms by pressing the test button built-in to the unit, as this is designed to simulate the detection of the target stimuli (usually smoke, heat, or CO) at the alarm sensor. You should test your alarms regularly to ensure they are protecting building occupants, preferably every week. For more detailed guidance, check the manual included with your 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.

How do I safely dispose of my old smoke alarms?

Safelincs is signed up to Valpak's WEEE (Waste Electrical and Electronic Equipment) Distributor Take-Back Scheme (Registration ID: 7370). Private households can therefore drop off their electronic and electrical fire safety waste at their municipal recycling centre when they are purchasing new products from us. To find your nearest recycling centre, please visit

How are smoke alarms fitted 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, this can be added to your basket through the ordering process.

Can air purifiers affect ionisation smoke alarms?

Yes, air purifiers may cause ionisation smoke alarms to sound falsely.

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?

The 9V alkaline batteries last 12-18 months. Lithium batteries will usually last 5x longer than their alkaline counterparts, achieving around 5 years lifetime. Some lithium cells are also rechargeable, and when used in a mains-powered alarm may last for the entire functional lifespan of the alarm. Newer alarm models may also feature a "sealed" lithium battery. These batteries are specialist components which are designed to not be removed or need replacing by the user, and have been tested by the alarm manufacturer to ensure they last for the lifetime of the alarm.

Please Note: the actual lifetime of your batteries depends on how often the alarms are tested or activated, as sounding the alarm draws more power than when the alarms are "waiting" to detect fire. You should also read your alarm's manual to make sure you only use the recommended types and brands of batteries, as failing to follow these instructions may cause the alarm to malfunction, not alerting you in the event of a fire, and might also invalidate the warranty.

Do I need an ionisation or optical smoke alarm?

We recommend using an optical smoke alarm in hallways, as these are less likely to go off because of cooking fumes from a connected kitchen. Optical smoke alarms are also ideal for living rooms, dining rooms, bedrooms, as they are good at detecting smouldering fires from soft furnishings. For landings we recommend ionisation alarms. Heat alarms are designed for kitchens and garages. No alarms should be installed in bathrooms.

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.

Can the mains powered smoke alarm range be connected to mains power via the lighting circuit?

Yes, hard-wired mains powered alarms can be wired to the unswitched live feed of the nearest frequently used lighting circuit.

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

It is usually recommended to install an optical smoke alarm in a bedroom. This is because optical smoke alarms are slightly quicker at detecting slow smouldering fires that can originate from upholstery type materials and over-heated wiring. Also, an optical smoke alarm would be less likely to sound a false alarm than an ionisation would, if steam/water droplets were present from the bathroom. Detectors should be installed as central to the room as possible; however for your application I would also consider the position of the en suite to make sure that the detector is not in the direct path of the joining door. This is just to try and avoid the chances of a false alarm. No detector is designed for use in bathroom areas.

My mains powered smoke alarm with lithium backup battery is beeping just after it has been installed. Why is that?

The lithium battery of the smoke alarm will have lost some of its charge in storage. While it is re-charging, the alarm is giving a low battery warning. This might take a few hours.

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.

How can I test my heat alarm?

Our heat alarms have test buttons. Press the test button for about five seconds. If you want to test the alarm with a heat source you can test the alarm with a hair dryer. Be careful as not to damage the plastic or sensor with excessive heat. Do not attempt test using open fire as this will damage the unit!

How can I make sure I hear the smoke alarm?

Our mains powered smoke alarms and radio-interlinked alarms are all interlinked. If one alarm detects fire it passes that information to all other smoke alarms in the same system. You can interconnect some of our alarms with other smoke alarms from our range. We also offer fire detection systems for the hard of hearing featuring strobe lights and vibration pads for the pillow.

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

EI battery-operated smoke alarms (have letter 'C' in the part number):With two strands of bell wire or twin cable. Kidde and Aico mains-powered alarms: With 3 core wire. All radio-interlinked smoke alarms: No signal cables required between the alarms.

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 I operate magnetic door retainers using a smoke alarm system without central panel?

Probably the easiest and option is to use Ei140 or Ei160 series smoke alarms. One of the units is mounted on an Ei128R relay base and all door holders would be wired through this relay base. The door holders used would be for example an electro magnetic door retainer. All units are run from a 230V AC supply. If any interlinked smoke alarm detects fire the relay contacts in the Ei128R will cut power to the door retainer which releases the fire door.

The Ei140 and Ei160 series alarms do have an internal battery back-up so the alarms would still sound in the event of a mains failure. However, the door holders or the Ei128R relay will not operate without mains power, which means they would go into safe mode and let the door close.

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.

How many alarms can be interconnected using radio frequency?

This depends from the model. Usually 12 or 15 alarms can be interconnected.

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.

What is carbon monoxide?

Carbon Monoxide (chemical symbol: CO) is a colourless, odourless, tasteless and toxic gas created by the incomplete combustion of fossil fuels (gas, oil, coal and wood), as used in our everyday appliances such as heaters, engines and boilers.

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.

What are the symptoms of carbon monoxide poisoning?

The symptoms of mild carbon monoxide poisoning are similar to those of viral cold infections: headache, nausea, dizziness, sore throat and dry cough. More severe poisoning can result in a fast and irregular heart beat, over-breathing (hyperventilation), confusion, drowsiness and difficulty breathing. Ultimately it leads to coma and death.

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

What are the regulations to testing CO detectors? Do I need to use test gas?

There is no legal or BSI requirement to test the CO detectors with a test gas. A weekly check with the test button is fully sufficient if you choose a quality CO detector. The test gas is offered as a 'belts and braces' option.

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.

Where should I install carbon monoxide detectors?

CO detectors should be installed near boilers and other potential sources of carbon monoxide. Keep a 1 to 3 meter distance to the boiler, etc. to avoid small start-up CO discharges to cause false alarms. As you are likely to be most affected by CO in areas of your home that you spend the most time in it is advisable to install detectors in those areas as well, such as the living room and bedrooms. It is also worth noting that while one detector is better than no detectors at all, larger homes may require several detectors to cover the property fully.

Which areas should I avoid installing carbon monoxide detectors?

Do not install CO alarms above or below windows.

Although most kitchens contain fuel burning appliances it is not recommended to install your detector there. Kitchens can be quite steamy while you are cooking and this may affect the sensor in the CO detector. Similarly it is not recommended to install detectors in dusty areas such as workshops or garages.

For more information please watch our video guide.


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