How to Bleed a Radiator
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If your radiator is cold at the top but warm at the bottom, trapped air may be stopping it from heating properly.
"Bleeding the radiator" releases the air and allows the hot water to circulate.
If the radiator is cold all over, the issue may be something else. If you're unsure, ask a qualified heating professional.
What you'll need
- Radiator bleed key
- Cloth or towel
- Small bowl or container
1. Turn off the heating
Turn off your central heating using your heating controls, then allow the radiator to cool before you start.
2. Find the bleed valve
The bleed valve is usually at the top corner/ side of the radiator.
Insert the radiator key into the square fitting.
3. Open the valve slowly
Place a cloth and bowl underneath the valve. Turn the key slowly anti-clockwise.
You should hear air escaping with a hissing sound. Don't open the valve too far.
4. Close the valve
When water starts to trickle out, turn the key clockwise to close the valve.
Don't over-tighten it.
5. Turn the heating back on
Wipe away any water, then turn your heating back on and allow the radiator to heat up.
It should now heat more evenly from top to bottom.
6. Check your boiler pressure
Bleeding a radiator can cause the pressure in a pressurised heating system to drop.
Check your boiler pressure and follow the manufacturer's instructions if it needs topping up. If you're unsure, ask a qualified professional.
When should you ask for help?
Get professional advice if:
- The bleed valve is stuck or damaged
- Water continues to leak
- The radiator is still cold after bleeding
- Your boiler pressure keeps dropping
- Several radiators aren't heating properly
- You're not comfortable doing the job yourself
A quick tip from Plumb Merchants
If your radiator is cold all over, bleeding it may not solve the problem. The issue could be the valve, system pressure, balancing or another part of your heating system.
If you're unsure what's causing the problem, talk to our team and we'll point you in the right direction.