Bleed a Hot Water Radiator

⏱️15 min per system💰$5🟢Beginner⭐4.9 (156 reviews)

Cold spots at the top of a radiator mean trapped air. 2 minutes per radiator restores even heat and cuts fuel bills.

Look at the top side of the radiator for a small square nut or slotted key socket. That's the bleed valve.

Water will come out — have an old cup or rag ready.

Use a radiator bleed key (or flathead screwdriver for some models). Turn counter-clockwise a quarter turn. You'll hear a hiss as air escapes.

Air hisses first, then water starts to drip or stream. As soon as you see steady water with no hissing, close the valve.

Bleed all radiators in the house, working from the lowest floor up. Then check boiler pressure — it may need topping up after bleeding.