Bleed your radiators the right way

Cold tops and hot bottoms on radiators usually mean trapped air. Bleeding is a 15-minute job with a key and a towel — messy only if you skip prep.

Follow this safety-first overview. Club adds system types, multi-floor order, and pressure rechecks.

Prep before you turn the key

Turn the heating off and let things cool enough to handle. Have a radiator key, cloth, and small bowl. Start on the lowest floor and work up in many systems so air migrates correctly.

• Open the bleed valve slowly until hissing air appears, then water.
• Close when water runs steady — don’t drain the system for fun.
• Check boiler pressure afterward and top up per your manual.

Tools and safety

• Radiator key or flat screwdriver depending on valve type
• A cloth and a shallow tray for drips
• Turn the heating off and let radiators cool before you start

Aftercare

If pressure keeps dropping after bleeding, you may have a larger leak — that’s beyond a towel-and-key afternoon. Listen for ongoing gurgles and recheck the coldest radiator the next morning once the system is hot again.

Hot bottom, cold top means air is stealing the heat you already paid for.

Full Club guide covers stubborn radiators, when bleeding isn’t the issue (stuck valves, sludge), and a seasonal checklist. Unlock to continue.

Cold top, hot bottom

Trapped air sits at the high point and blocks hot water from filling the panel. Bleeding releases that air until water sputters out. Have a cloth and small container ready; expect a little mess and check system pressure afterward on sealed systems.

• Turn heating off and let things settle before you start.
• Work from the highest radiator downstairs-to-upstairs patterns as your system requires.
• If you hear constant gurgling after, you may need a deeper system check.

The safe step-by-step with photos and “when to stop” notes are in the member article.