Carbon monoxide (CO) is an extremely dangerous substance to humans.  Aptly named the “silent killer” due to its difficulty to detect without an alarm.  In this blog, we answer some of the most common questions that we are asked by customers about carbon monoxide and carbon monoxide detectors, to help protect you and your family from a potentially life-threatening problem.

What is carbon monoxide (CO)?

Carbon monoxide is an odourless, tasteless and colourless gas that is toxic to humans.  Its unrecognisable traits make it very hard, if not impossible, for homeowners to detect.  CO leaks that are not addressed can lead to a very dangerous, sometimes deadly outcome for those subjected to the gas for a prolonged period.

What is a carbon monoxide detector?

A carbon monoxide detector is a safety device that can be easily fitted into a property to alert homeowners of a CO leak by raising an alarm.  Just like a fire alarm alerts the owner to a fire hazard, the CO detector alerts the homeowner of a carbon monoxide leak allowing them to escape a potentially life-threatening scenario.  

What are the main sources of carbon monoxide leaks?

Carbon monoxide can be produced by any fuel-burning device. In many households this will likely include:

  • Boilers
  • Gas fires
  • Central heating systems
  • Water heaters
  • Cookers
  • Open fires

Carbon monoxide is produced when fuels such as gas, oil, coal, and wood do not burn fully. Incorrectly installed, poorly maintained, or poorly ventilated household appliances, are the most common causes of accidental exposure to carbon monoxide so it is vital to have any appliances regularly serviced and cleaned by a professional so that they operate correctly and to prevent any issues which could lead to a CO leak a potential carbon monoxide poisoning.

Other possible causes of carbon monoxide poisoning include:

  • Blocked flues and chimneys – a blockage will stop products of combustion from escaping which will prevent the appliance from burning and operating correctly, which could cause carbon monoxide to be produced.
  • Burning fuel in an enclosed or unventilated space – for example, running a car engine inside a closed garage, or an open flue appliance in an enclosed area without ventilation.
  • Appliances which have not been cleaned or serviced – if the burner in the appliance is dirty then this will prevent the fuel from burning correctly and will cause incomplete combustion which can result in CO being produced.

What are the symptoms of carbon monoxide poisoning?

It is very easy to confuse CO poisoning with the flu, so make sure you are aware of the early tell-tale symptoms of carbon monoxide poisoning including:

  • Headaches
  • Dizziness
  • Nausea
  • Breathlessness
  • Collapsing
  • Passing out

A comprehensive list of symptoms and treatment can be found on the NHS website.

How to minimise the risk of carbon monoxide

According to Gas Safe Register, the most important thing you can do to minimise the risk of CO is to ensure that your gas appliances are safety checked annually by a Gas Safe registered engineer.

Installing an accredited carbon monoxide leak detector, or audible CO alarm, in your home or business is a good second line of defence, as they emit a sound when CO is detected. However, because an alarm only activates once there is CO present, you should never rely on them as your sole form of prevention.

Where should I install a carbon monoxide detector?

CO detectors should be fitted in every room that contains a fuel burning appliance. They should be installed in accordance with the manufacturer’s instructions, usually fixed to the wall at high level an appropriate distance from appliances. They typically have a life expectancy of 5-10 years and should be tested regularly.


The new rules regarding smoke and carbon dioxide alarms – as of 1 October 2022 – require social landlords to have a smoke alarm on every floor, not just private landlords, as well as a carbon monoxide alarm in any room with a fixed combustion appliance (such as a gas boiler or fire).  Plus, all smoke detectors and carbon monoxide alarms must be tested on the first day a tenant moves in. Landlords need to ensure they comply with the new requirements otherwise they may face up to a £5,000 fine.

In addition, landlords must also provide a valid Gas Safety Certificate and Energy Performance (EPC) certificate. Without these documents in place, a landlord will be in violation of the law and be unable to serve a Section 21 notice.

Tenants will still be responsible for testing alarms during the tenancy, but landlords will now be required to fix or replace any faulty alarms as soon as they are informed.

How often should I test my CO detector so make sure it is working?

It is important to test the alarm is working regularly. We recommend testing them at least once a month. If your detector has replaceable batteries, they should be changed at least every six months. Even with replacing the batteries, it will not last a forever, so make sure you check the specific lifetime of your detector, so you know when to consider purchasing a new one.

What should I do if my carbon monoxide detector goes off?

If the alarm starts bleeping, you can smell gas or think there might be a leak, ensure you carry out the following steps immediately:

  • SEEK PROFESSIONAL HELP – Contact a Gas Safe registered engineer to test and inspect the gas installation and appliances. Maintracts are proud to be members of the Gas Safe Register and we have an emergency team on call 24/7.
  • YOU FEEL UNWELL – See your doctor immediately or go to hospital. They can do a blood or breath test to check and can advise if you need treatment for CO poisoning.

Top tip:
Make sure any alarm you buy is marked EN 50291 and has the British Standards Kitemark. Good quality alarms are manufactured by FireAngel, Honeywell, Kidde and Aico. We do not recommend the use of ‘black spot detector’ warning strips because their warning is too easily missed and they do not emit a sound, so they will not alert you if you have a CO leak whilst you are asleep (this recommendation is in line with the Gas Safe Register advice).

We often read reports about CO poisoning on the news and in the press, but CO leaks really can happen to anyone. A carbon monoxide detector will save lives, and with good quality alarm starting at £20, there really isn’t any reason why you shouldn’t have one in your home.