Safety First: A Guide to Carbon Monoxide Alarms


carbon monoxide alarmsCarbon monoxide is produced by any appliance in your home that burns fuel such as gas, coal, wood and oil. There is no easy way to detect carbon monoxide levels in your home as the gas is tasteless, colourless and odourless, which is why it is important to have a carbon monoxide alarm. Every year deaths are caused from carbon monoxide poisoning that could have been avoided had an alarm been installed. 

What type of carbon monoxide alarm do I need?

When choosing a carbon monoxide alarm the first thing you want to do is avoid anything that doesn’t give you an audible alarm. There are some very cheap “detectors” on the market that show the presence of carbon monoxide when a spot turns black. These are not recommended as, by the time the spot has turned black, you too will have been exposed to carbon monoxide for some period of time. 

Any carbon monoxide alarm you choose should conform to British Standard EN50291, have a British Standards Kitemark or have a CE mark.

Your next decision will be whether you want an alarm that is powered by battery or mains power. If choosing a battery powered unit you will need to change the batteries regularly and, if choosing a mains powered device, make sure it has a battery backup in case of power cuts. 

Some carbon monoxide alarms and detectors will show you the level of carbon monoxide in the air on an LCD display. Others will just alarm without indicating the levels of carbon monoxide present. You will need to decide what level of information you need and whether knowing levels may be helpful.

How many carbon monoxide detectors/alarms do I need? 

The recommendation is that you have at least one alarm per floor. This will help make sure that the alarm can be heard throughout the house and, if you have more than one appliance, provide better coverage. 

Where should I fit my alarm?

First consult the instructions that come with the alarm. General guidelines state you should:

  • Install the alarm in the same room as the appliance but at least 1 meter away and not directly above any heat or steam.
  • Away from doors or windows as this may lead to the detector sensing lower carbon monoxide levels than are actually present due to draughts.
  • Don't place the alarm in a cupboard or area where it will be more difficult to heat the audible warning. 
  • Alarms can be installed at head height on a wall, on a bookcase or table.


How much do they cost?

Given a carbon monoxide alarm could save your life, the cost is negligible. Prices typically start at around £12 up to over £30. Alarms from £20 upwards typically offer LED displays showing the actual carbon monoxide level.


How long will a carbon monoxide alarm last?

This will depend on the manufacturer but typically they last around 5-7 years. There are models available that offer 10 years’ service and even some that will alarm you when they are reaching their end of life. It is important to make a note on the alarm of when it was purchased so that you can easily check how old it is and when it needs replacing.  A lifetime of 5-7 years doesn't however mean you don't need to change the batteries! 


A word of warning

Just like smoke detectors, carbon monoxide alarms need to be tested regularly to make sure they are working. This should be done at a minimum once a month, ideally once a week. Your alarm will have a test button, or similar, to check it is working correctly. 

Carbon monoxide alarms are not a replacement for smoke alarms. You need to have both. 

Fitting an alarm is NOT a substitute for having appliances serviced annually to check they are safe. 



More Information


For more information about carbon monoxide poisoning see our infographic.

The Gas Safe Register guide to carbon monoxide alarms:

More advice about carbon monoxide alarms can be found at the fire service page:



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