Half of households at greater risk of carbon monoxide poisoning: find out if this means you
Almost half of those we surveyed* don't get their boiler serviced annually - increasing the risk of it developing a dangerous fault, such as a carbon monoxide leak.
For Gas Safety Week 2022 (12th -18th September) we're urging anyone who hasn't had their boiler serviced in the past year to do so.
Gas Safety Week is a national safety campaign coordinated by Gas Safe Register. If your boiler hasn't been serviced in a year, now's the time to get it done. Call a Gas Safe Registered engineer to check your boiler is in good shape for the winter and reduce the risk of problems such as a carbon monoxide leak.
An annual boiler service also means your boiler is less likely to develop a fault, according to our research. Plus it will be significantly cheaper than waiting for your boiler to break and then paying for an expensive repair.
Read on to learn how to spot signs of a carbon monoxide leak, how much you should pay for a boiler service, and how much you could save by getting one.
Which? Trusted Traders - find a gas safe engineer in your local area to service your boiler.
Do boilers emit carbon monoxide?
When there isn't enough oxygen being supplied to the burning fuel in gas appliances, including your boiler, they can produce carbon monoxide.
Boilers usually carry any waste gases out of your home via the boiler's flue. But if your flue is blocked, or there's a leak in your boiler, then the carbon monoxide has nowhere to go but into your home.
Carbon monoxide is poisonous. It can make you seriously ill or even kill you.
It's also odourless, colourless and tasteless - so you can't rely on your senses to detect a leak.
When you get your annual boiler service, your engineer will check that your flue is properly maintained and the components are working as they should. This dramatically reduces the risk of your boiler leaking carbon monoxide.
A good carbon monoxide detector is essential for your home, but four in 10 models we've reviewed don't work as they should. Find out which carbon monoxide detectors passed and failed our tests.
Signs of a carbon monoxide leak
Signs that one of your gas appliances (including your boiler) has a carbon monoxide leak include:
- Dark, sooty staining on or around the appliance
- Increased condensation on the inside of your windows
- The flame struggling to stay alight
- A floppy yellow or orange flame, rather than crisp blue. You shouldn't, under any circumstances, open your boiler to check its flame, so look at your gas hob's flame next time you're cooking.
Find out how to get the best boiler service
Symptoms of carbon monoxide poisoning
The most common symptoms of carbon monoxide poisoning are:
- Headaches
- Dizziness
- Nausea
- Breathlessness
- Collapsing
- Losing consciousness
Find out more about signs of carbon monoxide poisoning and what to do if you suspect a carbon monoxide leak in our expert guides
Gas Safety Week 2022
Gas Safety Week is an annual event to raise awareness of gas safety and the importance of taking care of your gas appliances. Now in its 12th year, Gas Safety Week is coordinated by Gas Safe Register, the official list of gas engineers who are legally allowed to work on gas.
Badly fitted and poorly serviced boilers can cause gas leaks and carbon monoxide poisoning. By taking care of your gas appliances, you'll keep your home and loved ones safe.
Follow the Gas Safe Register's recommendations:
- Check your gas appliances every year This includes getting them serviced regularly by a Gas Safe registered engineer. If you're renting, make sure your landlord arranges this. Set a reminder so you don't forget at StayGasSafe.co.uk.
- Check your engineer is qualified for the type of gas work that needs doing Not all Gas Safe Registered engineers are qualified to carry out all types of gas work. You can find this information on the back of their Gas Safe ID card and on the Gas Safe Register website.
- Install an audible carbon monoxide alarm Make sure your friends and relatives have one too. Check they're marked EN50291 and display the British Standards' Kitemark (pictured below). To find the best models, see our Best Buy carbon monoxide detectors.
Learn about other ways to avoid a carbon monoxide build-up
The cost of a service vs the cost of one-off boiler repairs
Getting a service ensures your boiler will be in top working order. Unless you're paying for boiler cover that includes an annual service, you'll need to pay for it. But it will still be cheaper to pay for an annual service than to pick up the cost of fixing a broken boiler.
You can expect to pay around £80 for an annual service. Compare this with the cost of replacing the boiler parts that most often fail and, depending on the part, you'd typically save anywhere from £30 up to £219 by opting for the service.
The table below shows the four boiler parts that are most likely to develop a fault according to our Trusted Trader engineers, plus the average cost of a repair.
The cost will vary depending on factors such as your specific boiler and where you live, but our analysis should give you a good sense of typical costs.
| Boiler part | Average repair cost (part and labour) | |
 | Pressure-relief valve | £128 |
 | Automatic air vent | £117 |
 | Diverter / zone valve | £225 |
 | Printed circuit board | £313 |
Find out the costs for all 10 of the most common boiler faults in our guide to common boiler problems.
Need to find a boiler engineer? Use the Which? Trusted Trader website to find a Gas Safe Registered engineer local to you.
* Which? online boiler survey of 5,647 members of the public in May 2022 who've bought a new boiler in the past six years.
