• Nicholas Hall

How to bleed your radiator and when?


It’s something that we all know we should do, and its often a first port of call for many heating issues, you guessed it we are talking about bleeding your radiators. But do you actually know how and when to do it.

Check your radiator if it is the same temperature at both the top and the bottom

The best way to check if a radiator needs bleeding is to see if it is the same temperature at both the top and the bottom, if its cold at the top and hot at the bottom then there is air in it, and it needs to be bled. Bleeding is the process of releasing air from the radiator to allow hot water to circulate fully.

Get a right tool!

Although a simple process there is some equipment required, you’ll need a vent key, a containe and something to protect the floor in the area the radiator is situated. If you find yourself needing to bleed more than one radiator in your system, its best to start with the one furthest away from the boiler. If working over more than one floor start with the radiator’s downstairs.

Turn off your heating system before you do it

Before bleeding make sure your heating is turned off and the radiators are completely cool, you don’t not want to risk hot water spraying out of your radiator, it does not make for a pleasant experience.

How to

Once you have ensured the radiator is cold hold an old cloth, or a jug, under the bleed valve, and insert the bleed key. Turn the key anti-clockwise until air starts escaping (you'll hear a hissing noise). When water starts to escape, turn the key clockwise to re-tighten and close the valve. Repeat on other radiators that need attention, making your way back towards the boiler. Turn your heating back on and check if your radiators are now heating up correctly.

Still not solve the radiator issue?

Whilst bleeding the radiators will help you may find that it doesn’t solve all problems, nor does it take the place of a flush. It solely drains air from the system to help the radiators heat properly. If after bleeding you are still experiencing issues then its time to contact a heating engineer who will be able to advise you on your next steps.


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Ps. You can get the vent key from Amazon.