DIY guideRadiator
Bleed a radiator
Let trapped air out of a hot water radiator that's cold at the top.
- 10 to 20 min
- 5 steps
- Every step animated
5 steps
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Turn the heating off and let the radiators cool, so the water inside isn't hot.
Water from a hot radiator can scald.Look at a top corner of the radiator for a small square or slotted valve. This is for hot water radiators: a steam radiator has a different vent, so leave that one to a pro.
Hold the cloth and the cup under it and turn the key a quarter turn counterclockwise. You'll hear air hiss out.
When a steady trickle of water comes out instead of air, turn the key back clockwise to close it.
Turn the heating back on. If the boiler has a pressure gauge, check it's still in its normal range. If it's low, follow the boiler's manual or ask a pro.
What you need
- A radiator key (or a flat screwdriver, for some valves)
- A cloth and a small cup
Call a pro if
- It's a steam radiator
- The valve is stuck, broken, or keeps leaking
- The boiler pressure keeps dropping
- Radiators stay cold after bleeding
Free for every home. Handyman asks a few questions, then books a pro it trusts.
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