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How to install and look after smoke alarms


Installing smoke and carbon monoxide detectors in your home is one of the most important steps you can take towards keeping you and your family safe. Making sure that they are fitted correctly and regularly maintained and tested will ensure that they work as effectively as possible.

To understand why and where you should fit smoke and carbon monoxide alarms in your home, and to discover helpful fire safety tips including advice on creating an escape plan for your home, read our guide.

B&Q has a comprehensive range of smoke alarms and carbon monoxide detectors, as well as other fire safety products suitable for your home.


It is imperative that you test your smoke alarms and carbon monoxide detectors at least once a month, ideally once a week - less often than this and you will risk not discovering a broken alarm for too long.

  • They're easy to check; simply press the test button that is visible on the unit.
  • The unit will emit a loud alarm for approximately five seconds and then stop automatically.
  • There is an LED light that will also flash during the audible signal.
  • If your alarm does not sound or flash, this is a sign that the batteries need to be changed. You should do this immediately.
  • If your smoke alarms are linked with other smoke alarms, every individual smoke alarm should be tested.
Top tip: Making it easier to test

If reaching for the test button is too difficult or requires a ladder, try using the end of a long handled broom or mop to press the test button. Alternatively, upgrade your alarms to the latest smart systems. These clever alarms can self-test and they allow you to silence the alarm from your phone. No more climbing ladders every four weeks.

If your smoke alarm goes off without warning

This could be a sign that smoke and/or fire is present - always check there is no danger before silencing. Never ignore an alarm.

If your carbon monoxide alarm goes off without warning

This could be a sign that high levels of carbon monoxide are present.

  • Switch off gas-fuelled appliances (boiler, cooker, gas fire) and open doors and windows in the room to ventilate. Do not sleep in the room.
  • Evacuate the property and call the Gas Emergency Freephone Number 0800 111 999.
  • Seek medical advice for anyone suffering from the effects of carbon monoxide poisoning. Symptoms include headaches, nausea and flu-like symptoms.

Top tip: Worried that you won't remember?

Set a reminder on your phone or add it to your calendar - this way you shouldn't forget.

Although the smoke alarms are relatively maintenance-free, it’s still important to follow a few simple steps to ensure they are working properly:

  • Test your alarm at least monthly, or weekly if you can
  • Change the batteries yearly - and test the alarm after fitting these
  • Replace the batteries immediately if you hear the low battery warning - a low, beeping tone
  • Always change all the batteries in the alarm - when you update them annually, or if the low battery warning sounds.
  • Clean your smoke alarm every few months, using a slightly damp cloth or gently with a soft brush attachment on a vacuum cleaner. This will help to keep vents and sensors clear.
  • Do not open the case/ unit as this may damage the parts inside.

Important: The alarm may sound as you are cleaning it as you could knock the sensor. To be sure, check for smoke or fire, then silence when you’re sure it was accidental.

Do not use solvents or cleaners on your alarms as they may cause damage to the sensor or circuitry. Equally do not paint the alarm as this may block the openings and prevent smoke or carbon monoxide from entering the sensor.