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. 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. 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.

Ionisation alarms ionise the air between two electrodes. These are positively and negatively charged, creating a small current inside the chamber. 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 As of February 2022, the Nest protect smoke and CO alarm no longer meet the requirements of the new Scottish alarm laws. This is because, while it can be linked to other Nest alarms, it has no way of detecting heat rises or of being linked to another heat alarm.

Stay safe and get an early warning of a fire with the smartest, most effective smoke detectors for every budget

Interlinked smoke alarms will use the same optical or ionisation technology mentioned above, so, they're not a type of alarm in their own right.

The best smoke alarms you can buy in 2023 1. Google Nest Protect: Best smart smoke and carbon monoxide alarmDifferent 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. Now that the alarms law has changed in Scotland, you'll need to install interlinked heat and smoke alarms in your home. 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? 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.

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.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. Horizontal optical bench housing infra-red emitter and sensor, arranged radially to detect forward scattered light. Weight