Covid 19 update: We are still carrying out repairs and boiler replacements to make sure your heating and warm water is operational and effective. We employ extra safety measures and we make our customers' and engineers' safety a priority.

Can my boiler leak carbon monoxide?

Can my boiler leak carbon monoxide?

Fortunately, because carbon monoxide is so dangerous, it’s one of the things manufacturers and the law are very strict on. A well-maintained boiler should never leak CO, and if it does, it should be vented relatively harmlessly to the outdoors.

You should therefore take great care to ensure your vent is not blocked. This can happen through autumn leaves, snow, bird nests or any other build-ups, so make sure you check it regularly. It’s a good idea to have a guard over it to prevent things from getting near it.

The efficient running of the boiler should prevent dangerous levels of CO from building up, but when they are old or badly maintained, the fuel-air mix can become suboptimal, increasing the risk of CO production.

Badly maintained boilers can be inefficient, noisy and unreliable, but the biggest danger by far comes from carbon monoxide. We thought it would be useful to point out what it is, why it’s dangerous and how you can prevent carbon monoxide poisoning.

What is carbon monoxide?

You’ve probably heard of carbon dioxide (CO₂) – it’s the greenhouse gas that’s breathed out by animals and absorbed by trees, and it’s also what makes drinks fizzy. Each molecule has one carbon atom and two oxygen atoms. It’s a relatively harmless gas.

Carbon monoxide (CO) is altogether different. Its molecule consists of one carbon atom and one oxygen atom, but because of the way chemistry works, it isn’t comparable to CO₂. Carbon monoxide is formed when fuels like gas, oil, petrol or wood don’t burn properly.

Why is carbon monoxide so dangerous?

Carbon monoxide is dangerous for two reasons. First, there’s the effect it has on your body, which can be anything from headaches and dizziness to breathing difficulties and even death.

And second, it is completely colourless and odourless, so you don’t know you’re being poisoned by it. Furthermore, the effects can creep up on you over days, hours or weeks, so you might not notice yourself getting worse until it’s too late.

How do I prevent carbon monoxide risk?

The best way to prevent it is to always make sure your boiler has its annual service. The engineer will check for CO and ensure the fuel is burning completely, so the risk of CO will be minimised. They will also check your flue for blockages.

If your boiler is getting old, it can be inefficient and more prone to breakages through wear, so getting a replacement boiler might work out more cost-effective in the long run. Newer units run more efficiently and they are safer too.

For peace of mind, you should also invest in a carbon monoxide detector. They look similar to smoke alarms (and you can buy dual smoke/CO detectors), and are either battery or mains powered. Although all households are recommended to install at least one, if you are a landlord, it will be mandatory where appropriate to have a working carbon monoxide alarm.

Find out more about possible grants you could be entitled to for upgrading your boiler.

Published: 14 October 2021