Carbon monoxide detectors

Learn where to place carbon monoxide detectors in your home and what to do if you smell gas.

What is carbon monoxide?

Carbon monoxide (CO) is a colourless and odourless gas. It can be deadly if inhaled in high concentrations. It is produced when fuels such as gas, coal, wood, oil, or smokeless fuels are burned without enough oxygen. 

Gas appliances such as boilers, water heaters, and cookers can produce CO if they are not functioning properly. Also, if chimneys and vents become blocked, they can prevent CO from escaping outside. 

Carbon monoxide poisoning 

Carbon monoxide is a silent killer. You cannot see, smell, or taste the gas. This means you could be exposed to it without even realising it. CO poisoning can occur when there is a build-up of the gas in an enclosed space. Symptoms of CO poisoning include headaches, dizziness, nausea, and confusion, and in severe cases, can lead to coma or death. 

How to protect against carbon monoxide poisoning

A carbon monoxide detector measures the level of CO in the air, and it is the best way to alert you to a dangerous level of the gas in your home. These devices are often small and easy to install.  

Gas boilers and appliances should be serviced once a year by a Gas Safe registered engineer. Visit or call 0800 408 5500 

Where should I fit carbon monoxide detector?

Carbon monoxide detectors should be placed in all rooms where there is a carbon-fuelled appliance. These include boilers, fires (including open fires), gas or paraffin heaters, stoves or a flue. These do not need to be interlinked with your fire alarms. 

Once your carbon monoxide detector is set up, follow these steps: 

  • Ensure rooms with fuel burning appliances or boilers are properly ventilated 
  • Never block air bricks or vents 
  • Never block the outside grill of the flue 

What should you do if you suspect carbon monoxide is present?

  1. Turn off the gas  
  2. Turn off appliances  
  3. Open windows  
  4. Get everyone to exit the house  
  5. Call the emergency services or the Gas Emergency number 0800 111 999  
  6. If you are feeling unwell seek medical attention  

Further information 

Gas Safe Charity provide information and support, facilitate awareness and funding, work with charities and other organisations already trusted to go into people’s homes and deliver practical and preventative guidance.  

The Gas Safe Register is the official list of gas engineers who are qualified to work safely and legally on gas appliances.

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