Radiator advice
How to bleed a radiator.
Carefully and without the guesswork.
A radiator that is warm at the bottom but cold at the top, or makes a gurgling sound, may have trapped air inside. Bleeding lets that air escape.
What you will need
- The correct radiator key or tool for the valve
- A cloth and a small container for drips
- The boiler instructions, in case system pressure needs checking afterwards
Bleed the radiator
- Turn the heating offAllow the radiator to cool so hot water is not circulating while you work.
- Protect the areaHold a cloth and small container beneath the bleed valve, usually found near the top corner of the radiator.
- Open the valve slowlyTurn the key a small amount. A hiss usually means trapped air is escaping; there is no need to remove the valve.
- Close it when water appearsAs soon as the hissing stops and a steady trickle of water appears, close the valve gently. Do not overtighten it.
- Check the systemWipe the valve dry, turn the heating back on and check for leaks. On a sealed system, check boiler pressure against the manufacturer’s instructions.
When bleeding is unlikely to be the answer
Coldness at the bottom of a radiator, one radiator staying completely cold, repeated air build-up or regular pressure loss can have other causes. Continually bleeding or topping up the system may hide a leak or circulation problem.
Call for advice if you are unsure, if the valve leaks, or if the same symptom returns.
