DG Plumbing Heating Exeter · Devon

How to bleed a radiator (and when it's more than that)

Bleeding a radiator is one heating job you can safely do yourself. Here's how — and how to spot when it's not just air.

Get a free quoteCall Dec
Simple DIY steps When to call someone Free advice

If a radiator is warm at the bottom but cold across the top, there's trapped air in it, and bleeding it is a quick job you can safely do yourself. Here's the simple version.

How to bleed a radiator

  • Turn the heating off and let the radiators cool down.
  • Find the little square valve at the top corner of the radiator and pop a radiator key (or flat screwdriver on some) onto it.
  • Hold a cloth underneath, then turn it a quarter to half turn anticlockwise. You'll hear a hiss of air escaping.
  • When water starts to dribble out instead of air, close it back up snugly.
  • Once done, check your boiler's pressure gauge and top it up if needed.

When it's more than just air

Bleeding only fixes trapped air. It's a bigger problem if you notice any of these:

  • You're bleeding the same radiator again and again
  • The radiator's cold along the bottom rather than the top
  • The water that comes out is black and dirty

That's sludge, not air, and it needs the system flushing out. Declan Gent can sort that with a power flush — Dec covers Exeter and Devon and will tell you honestly what's needed.

Free quote, no obligation

Heating still not right?

Call or text Dec on 07493 772609, or send a few details and he’ll get back to you.

Get a free quoteCall Dec