CO Advice

What Installers 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.

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:


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 50292:2013 offers recommendations on the installation and maintenance of carbon monoxide alarms. See FireAngel’s ‘What is the British Standard BS EN 50292:2013 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.

Carbon Monoxide Travel Alarms

Most battery powered CO alarms 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.

Audible Alarm

Whilst there are ‘colour changing’ or ‘back spot’ tools available to detect carbon monoxide, it is paramount that you install an audible CO alarm. This gives tenant 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 tenants who may struggle to hear a standalone audible alarm, it is recommended to look for a carbon monoxide detector that possesses interlinking technology (see below).

Digital CO 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 give tenants 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).

Interlinking technology

Our Smart RF technology allows you to wirelessly interlink up to 50 smoke, heat and CO alarms throughout a property. Therefore, if one alarm goes off, they all do – providing an early warning to tenants, regardless of where they are/which floor they are on in the property.

By encompassing smoke, heat and carbon monoxide alarms in an interlinking network, this provides tenants with a faster warning to danger. As the alarms will also mimic the originating alarm’s sound pattern, this will signify the next steps required, e.g. if the CO sound pattern is heard opening all the doors and windows, turning off fuel-burning appliances, evacuating, and calling the National Gas Service in the event of a CO alarm. For tenants who are hard of hearing there are low-frequency sounders, or strobes and vibrating pads that can also be interlinked in a Smart RF network. For a full list, please see our Fire Safety Measures For Adults At Risk blog post.

Where to fit a carbon monoxide alarm

BS EN 50292:2013 states that carbon monoxide alarms should be fitted in:

  • CO alarms should be placed in the same room as fuel-burning appliances (either wall or ceiling mounted) – such as an open fire, gas cooker or boiler
  • Rooms where people spend the most time – such as living rooms
  • Additional alarms can be located in bedrooms, relatively close to the breathing zone of the occupants.
  • Any room that has a flue running through it
  • They should be at least 300 mm from any wall (for ceiling mounted alarms)
  • At least 150 mm from the ceiling, above the height of any door or window (forwall mounted alarms)
  • Between 1 and 3 m (measured horizontally) from the potential source of CO.

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.

See FireAngel’s “How to install a FireAngel CO-9X carbon monoxide alarm” video below:


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 Smoke And Carbon Monoxide Alarm (England) Regulations 2015 and Building Regulations Document J.

  • Building Regs J – requires CO alarms to be fitted when any new or replacement solid-fuel appliance is installed
  • 2015 Regulations – require CO alarms in private residential properties in any room with a solid fuel burning appliance.

Therefore these two pieces of legislation only require CO alarms to be fitted with solid fuel burning appliances (such as an open fire or woodburner) in private properties. Not only does this fall short for social housing CO legislation, but it also excludes appliances such as gas boilers – which are also a risk. Following the Grenfell Tower fire tragedy the Government have now commissioned an independent review of the Building Regulations and Fire Safety. The final report will be submitted in spring 2018 and this may well result in changes to the Smoke and Carbon Monoxide Regulations 2015 and the requirement for all landlords to install CO alarms in all private and public rented sector properties that contain a fuel burning appliance of any kind, including social housing. For best practice it is recommended that landlords fit CO alarms in rooms containing any fuel burning appliance, not just solid fuel appliances.

With regard to installing new or replacement combustion appliances it is recommended to follow the Scottish Technical Handbook, which stipulates that certified carbon monoxide alarms need to be fitted when any new or replacement fixed combustion appliance is installed.

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.

Make sure you subscribe to the FireAngel newsletter to ensure you stay up-to-date with new technology and changes to smoke and carbon monoxide legislation.