How to Bleed a Radiator: Step-by-Step Guide
Bleeding a radiator is one of the few plumbing jobs most homeowners can safely tackle without calling a plumber. Here's how to do it properly.
What you'll need
- ✓ A radiator bleed key (widely available and cheap)
- ✓ An old cloth or small towel
- ✓ A small container to catch drips
Step by step
Turn your heating on for 15-20 minutes so you can feel which radiators have cold spots, then turn the system off completely before you start - never bleed a radiator while it's hot and under pressure. Locate the bleed valve, usually a small square-shaped fitting at one of the top corners. Fit the key and turn slowly anti-clockwise, no more than a quarter to half turn. You'll hear air hissing out - keep the cloth handy underneath. Once the hissing stops and a small amount of water dribbles out, close the valve firmly (clockwise) straight away.
After you've finished
Check your boiler's pressure gauge. Bleeding radiators releases a small amount of water from the system, which can drop pressure below the recommended level (usually 1-1.5 bar). If it's low, top it up via the filling loop following your boiler's instructions.
If radiators need bleeding constantly, or your pressure won't hold, there's likely a leak somewhere worth investigating - our leak detection team can help track it down.
Need help now?
Our Swindon plumbing team is available 24/7.