CO Advice

What to look for in a carbon monoxide detector and where to fit

Carbon monoxide (CO) is a toxic gas that cannot be smelled, tasted or seen. A by-product of incomplete combustion, CO can be produced in the home when fuel-burning appliances (such as boilers, gas fires and cookers) develop a fault, or are poorly maintained.

According to the Department Of Health, accidental carbon monoxide poisoning accounts for 50 deaths per year, and as many as 4,000 medical visits. It is therefore paramount that housing providers protect their tenants by installing carbon monoxide alarms in their properties and have fuel-burning appliances regularly checked by registered engineers.

What does a carbon monoxide detector do?

Carbon monoxide detectors alert you to the presence of the poisonous gas carbon monoxide (CO). CO is a colourless, odourless gas that cannot be detected by human senses. Installing sufficient audible CO detectors in your home ensures a rapid alert to the detection of CO providing you with vital time to seek fresh air.

Do I need a carbon monoxide detector? 

A carbon monoxide detector is recommended in rooms where there are fuel-burning appliances, such as gas boilers, log burners or open fires, or rooms that have a flue running through them.

However, as carbon monoxide can pass through walls, even if your home does not contain any fuel-burning appliances, the poisonous gas can be caused by your neighbours’ appliances. Therefore, installing an audible CO alarm in the rooms most often used, including bedrooms, or near any fuel-burning appliances, will ensure you are alerted to the potential presence of carbon monoxide at home or when travelling.

Having decided you want to update or buy a carbon monoxide detector for your property, it is important you know what technology is available and where to fit the CO alarm. Here are the main things to consider before making your purchase.

Third-party certification

Ensure the carbon monoxide alarm complies with British Standard EN 50291 and carries a British or European approval mark, such as a Kitemark. The British Standard BS EN 50292:2023 offers recommendations on the installation and maintenance of carbon monoxide alarms. See FireAngel’s ‘What is the British Standard BS EN 50292:2023 for more information.

Battery or hard-wired?

There are equal benefits to battery and hardwired CO alarms. Whilst tamper-proof mains powered alarms require professional installation by an electrician, there are also battery powered CO alarms available that are both tamper-proof and have a sealed for life lithium battery (usually 7 to 10 years). This enables you to trust the product will be working for the entire of its product life, and will continue to work in power cuts. Although it is still important to test alarms and keep them free from dust by gently vacuuming the case with a soft brush as required.

When looking for a battery-powered carbon monoxide detector, ensure you are familiar with its low battery warning signal e.g. a warning chirp or a visual display.

Portable carbon monoxide detectors for travel 

Most battery powered CO detectors are portable which makes them ideal for taking on holiday. In hotels, guests are often unaware that they are sleeping next to boiler rooms or above a room with a fireplace; if you’re camping, CO can enter your tent from a smouldering BBQ outside; plan to take a CO alarm to any future holiday destinations to ensure you are safe.

Take a battery powered CO alarm when going away to ensure you stay protected from carbon monoxide when on your travels. Whether it’s a week in sunny Spain, a cottage weekend in the Cotswolds or a camping / caravan break UK or abroad, remember to pack a CO alarm every time you go away and keep yourself and others protected from CO.

Summer fire safety

Audible CO detectors 

Whilst there are ‘colour changing’ or ‘black spot’ tools available to detect carbon monoxide, it is paramount that you install an audible CO alarm. This ensures a clear indication that there is a problem, and as quickly as possible, a feature that is paramount given the speed at which this toxic gas can spread, and how quickly it can start having negative effects on the body. For vulnerable people or tenants who may struggle to hear a standalone audible alarm, it is recommended to look for a carbon monoxide detector that possesses interlinking technology as found in our Pro Connected range of alarms.

CO detectors with digital display

For ultimate protection, carbon monoxide detectors with digital displays can be used. This shows the peak level of CO detected over a 4 week period – a quick visual indication that will indicate if CO (measured in parts per million) is present, even if concentrations are below the level that triggers the alarm. Therefore a quick and simple way to provide an early visual warning and if the alarm does sound a quick way to see the highest level of CO detected during that time (although this feature may result in the alarm costing a little more than industry average as a result).

FireAngel’s FA3322 Digital Carbon Monoxide Alarm offers the highest level of CO detection for your home and replaces end-of-life CO-9D alarms. The multi‑functional LCD display changes colour to indicate various warnings and instructions to homeowners and tenants for clear safety advice.

Where should I put my carbon monoxide detector? 

British Standard BS EN 50292:2023 states that carbon monoxide alarms should be fitted in:

  • Rooms that contain any fuel-burning appliances (such as an open fire or gas boiler) – CO alarms may be interlinked with other alarms in the property such as smoke or heat, in accordance with EN 50291-1:2018, to ensure appropriate early warning
  • Rooms where people spend the most time – such as living rooms
  • Rooms where people sleep
  • Any room that has a flue running through it

The British Standard EN 50292 standard also recommends that an alarm is not fitted:

  • Where it can be obstructed
  • In an enclosed space
  • Directly above a sink
  • Next to a door, window, extractor fan, air vent or similar ventilation opening
  • Where the temperature may exceed 40 ºC or drop below –5 ºC.


The importance of installing CO detectors is reflected in recent updates to legislation. Currently Carbon Monoxide Regulations vary throughout the UK, but the main legislation that applies to England and Wales includes the Carbon Monoxide Alarm (Amendment) Regulations 2022 and Building Regulations Document J.

  • Building Regs J – requires CO alarms to be fitted when any new or replacement solid-fuel appliance is installed
  • 2022 Regulations – Ensure a carbon monoxide alarm is equipped in any room used as living accommodation which contains a fixed combustion appliance (excluding gas cookers), and ensure carbon monoxide alarms are repaired or replaced once informed and found that they are faulty.

Fundamentally, advances in technology will make it easier – and possibly cheaper in the long run – to protect tenants from fire and carbon monoxide. It is becoming progressively easier for landlords to offer a higher standard of care to tenants, whilst simultaneously managing their own liability risk.

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