Bleeding Radiators Safely
A radiator that's cold at the top with a warm bottom usually has trapped air, and bleeding it is one of the few jobs most people can do safely themselves with basic care..
A radiator that's cold at the top with a warm bottom usually has trapped air, and bleeding it is one of the few jobs most people can do safely themselves with basic care.
Before you start
Turn the heating off and let radiators cool slightly so escaping water isn't scalding, and have a cloth and small container ready.
The bleed itself
Use a radiator key to turn the valve slowly until you hear hissing air, then close it firmly the moment steady water appears.
After bleeding
Check the system pressure afterwards, since bleeding radiators typically drops it slightly and it may need topping up.
Signs a radiator needs bleeding
- Cold patch at the top of the radiator
- Gurgling noises from the radiator or pipework
- Heating takes longer than usual to warm the room
Who does the work
- Gas Safe registered engineers — registration 554328
- Worcester Bosch accredited installer
- John The Plumb Ltd, company registration 10026483
Still getting cold radiators?
If bleeding hasn't sorted it, tell us which radiators are affected and we'll work out whether it's sludge, balance or something else.
Questions we get asked
How often should I bleed radiators?
Only when you notice symptoms; there's no need to do it on a fixed schedule if radiators are heating evenly.
Is it safe to bleed a radiator myself?
Yes, it's a low-risk task, just take care with the hot water and don't force a stiff valve.
What if bleeding doesn't fix the cold patch?
A cold patch lower down or one that returns quickly can mean sludge build-up, which points towards a power flush rather than bleeding.