Fire and rescue services attended over 150,000 fires last year in England alone, and while the number of fire fatalities dropped to their lowest ever figure, 240 people still lost their lives. Buying a smoke alarm is one of the most important steps you can take to protect your home, your life and the lives of your family and friends. It can give you early warning of a fire before it spreads, and the best chance of getting everyone safely out of the house. This could be critical if you’re out when there’s a fire. All of the smart smoke alarms we've tested are optical models. The latter are pricier when you buy for the first time, but you won't have to factor in the expense of replacement battery costs. Horizontal optical bench housing infra-red emitter and sensor, arranged radially to detect forward scattered light. Weight Batteries used to be the weakness of most household smoke alarms, requiring replacement every year or so and usually running out of charge, causing the low battery alarm to ring, in the middle of the night. As with carbon monoxide alarms, the trend is now towards alarms with a built-in, 10-year lithium battery, designed to work for the alarm’s effective lifespan. In Scotland, these are now a legal requirement. In England and Wales, however, you can still buy and use alarms with a replaceable 9V battery, and these often work out cheaper. We’d recommend paying extra for the convenience and peace of mind, but the choice is yours. Is there anything else worth looking out for?

You can put them in kitchens and garages because they’re not prone to false alarms from cooking or exhaust fumes. But they are slower to respond than smoke alarms. All of the major manufacturers (Aico, FireAngel and Kidde) make smoke and heat alarms that will work in combination with one another and we have tested pairs of smoke and heat alarms from each of them. As a rule of thumb, it’s best to use optical alarms in living rooms, bedrooms or downstairs hallways where you either have a lot of upholstered furniture and soft furnishings or the alarm is likely to be set off by cooking fumes. Keep ionisation alarms for upstairs hallways or areas where dust or exposure to the elements (say, through an open door) might potentially set off an optical sensor. If in doubt, go optical or use a multi-sensor alarm. Use of ionisation alarms is generally being discouraged by many fire services, and some manufacturers have now discontinued their ionisation products.Of course, it is entirely possible to get connected smoke alarms that hook up directly to your home network via Wi-Fi, or through a proprietary connection or a Zigbee or Z-Wave hub. The advantage with these is that they can warn you of a fire through an alarm or alert on your smartphone, and also, with some systems, trigger smart lighting to come on. How we test smoke alarms Heat (thermal) alarms detect heat (hot air) instead of smoke. The alarm is triggered when the temperature within the sensor chamber reaches over 58 degrees Celsius – generally when a fire is well established. This also allows the sensor threshold level to be increased, thereby improving the signal to noise ratio and reducing susceptibility to false alarms. The ALN-EN(BLK) smoke chamber is easily removed or replaced for cleaning and utilises a unique improved baffle design which allows smoke to enter the chamber whilst keeping out ambient light. On a lighter note, Google’s data also revealed that the day when smoke alarms are most likely to sound in the UK is pancake day. Is the Nest Protect smoke and CO alarm suitable for homes in Scotland now that the law has changed? If you buy a battery-powered smoke alarm (rather than a mains-powered one), you'll need to decide whether you want one with a replaceable 9V battery, or sealed fixed-life battery

Smart smoke alarms are designed to sound the alarm when they detect smoke, as a conventional smoke alarm would. But the unique selling point of a smart smoke alarm is the ability to send alerts to your phone when there’s a fire. Different makes and models will be slower or faster to detect smoke coming through and have different alarms working at different volumes. Some even feature voice alarms or strobing lights. However, any alarms sold in the UK have to meet BS EN 14604:2005, which specifies the requirements, tests and performance criteria for smoke alarms using optical or ionisation sensors. Heat alarms are governed by the separate BS 5446-3:2003 standard. These alarms are more sensitive to smaller particles of smoke produced by the flaming stage of fires than optical alarms, and more easily triggered by cooking – causing false alarms. Wireless devices communicate with each other and other devices without the use of connecting wires. This can be through interlinking by radio or through wi-fi. Smoke particles change the balance of the current. When this happens a signal is sent to the integrated circuit and the alarm sounds.

INTRUDER ALARM KITS

Now that the alarms law has changed in Scotland, you'll need to install interlinked heat and smoke alarms in your home. Some smart models sound an alarm on your smartphone and through the alarm itself when triggered – this is the most helpful kind of smart alarm. If you own a Nest smoke and CO alarm, you will be able to continue to use it but it will need to be in addition to interlinked smoke and heat alarms. As smoke enters, the infrared light is scattered onto the photodiode light receptor, triggering an alarm. They detect the larger smoke particles from slower smouldering fires. If it does go off inadvertently, the large, central test/mute button makes it easy to silence, saving your ears from a thrashing. As with the Pro Connected, it buys you ten minutes to clear the air, while a “sleep easy” function gets you eight hours of quiet if you press the button once the low battery warning starts. Little touches such as this elevate the ST-622Q above your run-of-the-mill smoke alarms, making it one of the best options for most households.

Pros: Can suit dustier areas, such as lofts, the area near your bathroom or rooms where people smoke. An interesting by-product of the new breed of smart alarms is the fire-related data being collected, as is the case with Google, which makes the Nest Protect smoke and CO alarm. Google told us that it uses data from its alarms to provide ‘meaningful insights’ for its customers and to improve the product. So if you’re out of your home and not near your phone when the messages come through, you’ll have no way of knowing the alarm was sounding. Meanwhile, a system of colour-coded indicators on the central ring gives you visual alerts and updates, and even a subtle night light if you pass it in the dark. It’s more expensive than other smoke alarms, but if you’re invested in making your home smarter, this is the alarm to buy. Pros: Good for bedrooms, landings and hallways, and near to kitchens as they aren’t as prone to false alarms from cooking.Their distinguishing feature is the fact that they can be linked to other alarms, both heat and smoke alarms, so that when one senses danger they all sound.