How to Bleed a Radiator
Quick Answer
Turn off the heating, use a radiator key to open the bleed valve, release air until water trickles out, then close it.
How to troubleshoot How to Bleed a Radiator
If your radiator is cold at the top but warm at the bottom, it likely has trapped air. Bleeding the radiator releases the air and restores full heat output.
Step-by-Step Fix
- Turn off your central heating and allow radiators to cool completely.
- Place a towel or small container underneath the radiator bleed valve.
- Insert a radiator bleed key into the valve and turn it counter-clockwise slowly.
- You will hear a hissing sound as air escapes; wait until water begins to trickle out steadily.
- Turn the key clockwise to close the valve tightly.
- Check the boiler pressure and top up if necessary, then turn the heating back on.
Common Error Codes
| Code | Meaning | Resolution |
|---|---|---|
| No water comes out | Valve is blocked or boiler pressure too low | Check pressure gauge and repressurise if needed; if blocked, call a technician. |
| Water splutters | Air still trapped | Continue bleeding until a steady stream of water appears. |
Frequently Asked Questions
Do I need to turn the heating off before bleeding?
Yes, to prevent burns and ensure the system is not under excessive pressure.
What if I don't have a radiator key?
A flat-head screwdriver can fit some bleed valves, but a key is recommended.