How to bleed a radiator

When bleeding helps

Air at the top of a radiator stops hot water circulating, so the top stays cool while the bottom may feel warmer. Bleeding releases that air. If the radiator is cold at the bottom, sludge is more likely — bleeding alone will not fix that.

Steps

1. Turn the heating off and allow radiators to cool.
2. Put a cloth and shallow container under the bleed valve (usually a square key point at the top corner).
3. Turn the bleed key anti-clockwise a fraction until air hisses out.
4. When a steady trickle of water appears, close the valve firmly — do not over-tighten.
5. Check boiler pressure on a sealed system and top up if the handbook says you should after bleeding several radiators.
6. Restart heating and confirm the radiator warms evenly.

Safety notes

• Hot water and steam can scald — cool the system first.
• Protect floors and carpets from black system water, which can stain.
• If the valve stem breaks or will not close, shut the lockshield and wheel-head valves if present and call a plumber.

When to call a professional

Call for radiator repair if valves leak, the radiator still will not heat, or pressure loss continues. For cold bottoms and sludge, ask about power flushing. Guidance on radiator cold at the bottom and boiler pressure may help you describe the fault. Book via Derby 01332 314146 or the quote form.