I'm a bit new to central heating. One radiator will not work when the
head is on - it looks like one of these:

http://www.heatingcontrolsonline.co....ead-p-690.html

If I take the head off the valve pin on the radiator works fine and
the radiator blasts into life - full on.

If I put the head on the radiator shuts off.

If I look at the bottom of the head and rotate from hot to cold and
vice versa I can't see any movement - should I?


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AnthonyL