How To Bleed Your Radiators

02-06-2018

Air trapped in your radiators could be the cause of cold spots, longer than usual to heating times, or high water pressure in your boiler.

Bleeding your radiators can improve heating efficiency, remove cold spots in your radiators and reduce pressure in your boiler. It is a task that can be completed without the need for a Gas Safe registered heating engineer. However, if you're unsure about bleeding your radiators, encounter any issues or have any questions, please contact our friendly team on 01295 224844, or email hello@mnheating.co.uk and we'll happily assist you.

Before attempting to bleed your radiators, check your heating system is cold and your boiler has not been in operation for at least one hour.

Your boiler heats water that is then circulated to radiators, outputting heat around your home. Heating water creates steam that could become trapped and cause cold spots often nearer the top of your radiators, which reduces their efficiency. Trapped air can also increase the water pressure in your heating system. It is recommended that the pressure gauge, usually found on the front of your gas boiler, reads between 1 and 2 bar.

To bleed your radiators you'll need a radiator key, which can be purchased at your local DIY store, and an old towel. It's best to start with radiators on the ground floor farthest away from your boiler, then move upstairs (again, starting with the radiators farthest from your boiler).

At the top of the radiator at one end, there will be a valve where the radiator key will fit. Hold the old towel closely beneath the valve and carefully turn the radiator key anticlockwise until you hear air hissing out of the open valve. Be ready to close the valve as when the trapped air has escaped, water will follow (this is why it's important to ensure your heating system is cold, otherwise it would be hot water). Ensure to securely close the valve, wipe down any spilled water, and repeat this process with all your radiators. Once completed, check the pressure gauge reads between 1 and 2 bar on your boiler. If you have a combi boiler, you may need to increase the pressure after bleeding your radiators.

Should the cold spots and slow heating times remain, you may have excess sludge, deposits, rust and debris in your radiators and may benefit from a power flush of your heating system. If a high boiler pressure remains and you've checked the valves of your filling loop are securely closed, you may have an issue with your boiler's expansion vessel, pressure gauge or filling loop. Remember, only Gas Safe registered heating engineers are legally allowed to work on gas appliances.

If you're unsure about bleeding your radiators or still have issues after following these instructions, don't hesitate to contact our friendly team on 01295 224844 today.

Recap

1. Switch off your boiler and ensure your heating system is cold for at least one hour.
2. Check your radiators for cold spots and/or longer than usual heating times.
3. Check the pressure gauge, which is often found on the front of your boiler.
4. Start with radiators on the ground floor, farthest from your boiler.
5. Hold an old towel beneath the valve at the top of one end of the radiator.
6. Carefully turn the radiator key anticlockwise until you hear air hissing out of the valve.
7. Be ready to close the valve as water will follow once all the trapped air has been released.
8. Wipe down any spilled water, and repeat the process with other radiators.
9. Check the pressure gauge on your boiler reads between 1 and 2 bar.
10. If you have a combi boiler, you may need to increase the water pressure.