Do you have a safe and reliable carbon monoxide alarm in your home?
With Gas Safety Week 2024 around the corner it's important to take some time to ensure your carbon monoxide (CO) alarm is up to scratch.
High CO levels have the potential to kill in minutes, so the consequences of not being alerted about the presence of CO in your home can be deadly.
Below we take a closer look at how CO alarms work and highlight the signs of exposure to carbon monoxide.
Plus, we explain how you can use the Which? Trusted Traders website to find a reliable gas engineer.
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What is carbon monoxide?
Carbon monoxide is a poisonous gas that can make you seriously ill if you breathe it in. It's produced by fires and appliances that burn gas, wood, oil or coal.
As carbon monoxide is colourless and odourless, you won't notice if a fuel-burning appliance in your home is releasing it.
What is a carbon monoxide detector?
Carbon monoxide alarms are designed to sound when the concentrations of CO in the air are enough to harm you.
A good CO alarm will sound when it detects the gas and it will be loud enough to alert everybody in the house. However, our own expert tests prove that not every CO alarm you can buy will do this effectively.
A CO alarm makes a noise when there are 50 or more parts per million (PPM) of CO in the air. Alarms are designed to sound more quickly when higher and more dangerous concentrations of the gas are present.
At Which?, we test whether CO alarms can detect the presence of CO more than 30 times for each brand. Only those that sound the alarm every time CO is present become Best Buys.
See which models we recommend, and which are Don't Buys, in our carbon monoxide detector reviews.
Who needs a carbon monoxide detector?
If you have an appliance that burns fuel in your home, such as a gas, LPG, oil or wood boiler, you'll need a carbon monoxide alarm in every room that fuel is burned in.
You should also install a CO alarm if you have a wood or coal-burning fire or a wood burner.
It's important that the CO alarm is positioned high up in the same room as the potential source of carbon monoxide. But don't install it above a source of heat or steam.
For more tips on finding the perfect position for your CO alarm, see our guide on how to install and test carbon monoxide detectors.
How to see if there is carbon monoxide in your home
Although this poisonous gas is odourless, there are still a number of ways to detect its presence.
Look for a lazy yellow or orange flame on your hob, instead of the usual clear blue flame. You'll also want to check for staining around your fuel-burning appliances, as this is a sign of CO build-up.
Note that carbon monoxide will cause your boiler's pilot light to blow out regularly. Plus, it can lead to increased condensation on windows.
For more tips on keeping your home safe, see our advice on five ways to avoid a carbon monoxide build-up.
What should I do if my CO alarm goes off?
When you hear a CO alarm sound, you'll need to immediately follow these steps.
- Open all of the doors and windows in the house – this will help to clear some of the gas.
- Turn off your fuel-burning appliances – this includes boilers and fires. You should also avoid switching on any lights.
- Leave the house and seek medical advice – if you're showing symptoms of CO poisoning (details below), contact a doctor or call 999 for an ambulance.
- Contact an emergency advice number – reach the Gas Emergency Service on 0800 111 999. If you use oil to heat your home, call Oftec, the trade association for liquid fuel heating equipment manufacturers, on 01473 626 298.
- Get your appliances serviced – dangerous levels of carbon monoxide need to be dealt with as soon as possible. Consider reaching out to a Which? Trusted Trader.
Carbon monoxide poisoning symptoms
Low-level exposure
Headaches are the most common symptom of mild CO poisoning. Other symptoms associated with CO poisoning include dizziness, feeling sick and vomiting, confusion and tiredness, stomach aches, shortness of breath and difficulty breathing.
Low-level exposure to CO can feel like food poisoning or the flu without a high temperature. If you're exposed to CO at low levels for a long period of time, concentration may become difficult and you may experience frequent mood changes.
High-level exposure
Inhaling high concentrations of CO can produce more severe symptoms including intoxication, vertigo, loss of coordination, breathlessness, tachycardia, chest pains, seizures and unconsciousness.
In the worst cases, breathing high concentrations of carbon monoxide can lead to death in minutes.
Symptoms in children and pets
Pets and children can be the first to show signs of carbon monoxide poisoning. Children have smaller lung capacities than adults, so they're more sensitive to high levels of the gas and can be affected more quickly.
Pets can also be more at risk of carbon monoxide poisoning based on them being left in the same room as an appliance that's producing CO, such as a faulty boiler in a kitchen. Small pets, such as birds, can be particularly badly affected by a CO build-up.
For more information on spotting the signs of CO poisoning, see our guide on carbon monoxide symptoms.
How to choose the best carbon monoxide detector
When you're shopping for a CO alarm, look for accreditation marks, such as the Kitemark, that show the alarm has passed standard CO detection tests.
Typically, well-known brands of alarm that you see on the high street pass all of our carbon monoxide detection tests.
But our expert lab tests have also uncovered CO alarms that failed to sound when tested. We've found dangerous CO alarms that don't function reliably for sale on online marketplaces eBay, Amazon, Wish and AliExpress.
Make sure you know what to avoid, and find out more about the specific unsafe alarms here: Killer carbon monoxide alarms still on sale through online marketplaces.
For every CO alarm that we test, we answer important questions including:
- How well does it detect carbon monoxide?
- Will it be loud enough for you to hear when it goes off?
- Are the instructions safe regarding where to install the carbon monoxide alarm?
Our reviews cover plenty of brands, including Aico, FireAngel, Honeywell, Kidde and Nest.
To ensure you're buying a CO alarm that responds as soon as it needs to, discover Best Buy models with our guide to the best carbon monoxide detectors.
Use Which? Trusted Traders to find a gas engineer
If you're looking for someone to fit a new boiler or gas fire for you, or you need an engineer to service a fuel-burning appliance, Which? Trusted Traders can help you find a Gas Safe Registered engineer.
Before allowing traders to join the Which? Trusted Trader scheme, we check applicants' credit reports, find out how happy their customers are with the work they've carried out and examine how they run their businesses.
Head to Which? Trusted Traders to find a Gas Safe Registered engineer local to you.
