How do I bleed a radiator?
Bleeding a radiator releases trapped air using a radiator key on the bleed valve — turn off the heating first and have a cloth ready to catch water.
How to Bleed a Radiator
- Turn off your heating and let radiators cool
- Locate the bleed valve (small square-shaped valve at the top corner of the radiator)
- Insert a radiator key and turn slowly anti-clockwise — you'll hear a hissing sound as air escapes
- Have a cloth ready — once water starts to trickle out steadily (no more hissing), close the valve
- Check system pressure afterwards and top up if it's dropped below the recommended level
When to Call an Engineer
If radiators need bleeding frequently, there may be an underlying issue such as a leak, corrosion producing gas, or a faulty auto air vent. RARE can diagnose recurring air problems and rebalance your system — call 020 7458 4949.
Reviewed by RARE Plumbing London Engineering Team — Gas Safe registered engineers serving prime London since 2013.
Related Service
Central Heating
Expert engineers across prime London