Feel the radiator at the top, if it needs bleeding it will be cooler at the top than at the bottom.
1. Turn off the pump.
2. Get a radiator bleed key (has a square hole in it)
3. At the top of one end of the radiator there is a square recessed bleed screw.
4. Get some rags or an old towel place below the bleed screw to catch the water that will eventually come out..
5. Starting with the lowest radiators first, insert the key into the bleed screw and turn anticlockwise, you will hear hissing of the air coming out, you can vary the speed of this air by slowly turning the key more. When the air comes out the water level rises in the radiator and will eventually come bubbling out the bleed screw where you catch it in the rags / towel.
Wait for the bubbling to stop then tighten the bleed screw clockwise (but only a pinch...not too tight!...otherwise you will strip the thread)
Do all the radiators in this manner, lowest first (because air rises).
If you still have a problem then the central heating pump will need bleeding and that is done by first switching it off then releasing the large screw headed cover at the centre of the pump (usually black with a big screwdriver slot in it) a little until you hear the rush of air and then the bubbles. Retighten this cover and check all the radiators again.
Switch the pump back on again.
You are done.......easy eh!
Bob the Builder, February 2005
