There are two types of smoke alarm:
- Ionisation alarms are the cheapest and most readily available smoke alarms.
- They are very sensitive to 'flaming fires' - fires that burn fiercely, like chip-pan fires. Ionisation alarms will detect flaming fires before the smoke gets too thick.
- Are more expensive. However, they are more effective at detecting slow-burning fires, like smouldering foam-filled furniture or overheated wiring.
- Are less likely to go off accidentally and so are best for ground-floor hallways and for homes on one level.
For the best protection, you should install one of each. However, if you can't have both, it's still safer to have either one, rather than none at all.
Whichever model you choose, you should make sure that it meets British Standard BS EN 14604 and ideally also carries the British Standard Kitemark.
The different smoke alarm models available
A lot of people forget to check their smoke alarms, so the best choice of power supply is usually the one that lasts longest.
An 'ionisation battery alarm' is the cheapest and most basic smoke alarm available. An 'optical battery alarm' is a little more expensive. Both run off 9-volt batteries.
Battery alarms with an emergency light
These come fitted with an emergency light which comes on when the alarm is triggered. They are particularly suitable if someone in your house has hearing difficulties and may help light up an escape route.
Alarms with ten-year batteries
These are slightly more expensive, but you save on the cost of replacing batteries. They are available as ionisation/optical alarms and are fitted with a long-life lithium battery or a sealed power pack that lasts for ten years.
These are powered by your home's electricity supply and need to be installed by qualified electricians. There's no battery to check, although they are available with battery back-up in case of a power cut.
Interconnecting or linked alarms
Some alarms can be connected to each other so that when one senses smoke, all the alarms in the property sound. They are useful for people with hearing difficulties and also in larger homes.
Mains-powered alarm with strobe light and vibrating pad
These are designed for people who are deaf or have hearing difficulties. If there's a fire, the alarm alerts you with a flashing light and vibrating pad - which is placed beneath your pillow.
Mains-powered alarm which plugs into a light socket
This type of alarm uses a rechargeable battery that charges up when the light is switched on. It lasts for ten years and can be silenced or tested by the light switch.
People who are deaf or hard of hearing need additional ways of making them aware the alarm has been activated, including vibrating pads and flashing strobe lights.
A whole range of alarms has been designed specifically for the hard of hearing, with features ranging from strobe lighting and vibrating alarms to small wearable radio linked pagers.
These specialist alarms can save lives, alerting people to a fire in their home even if they remove their hearing aid at night.
British Standard BS5446-3:2005, which was amended in 2007, specifies smoke alarm kits for deaf and hard of hearing people. Products made to this standard give deaf people assurance of quality smoke alarms designed to meet their needs.