Low pressure in heating system

Albermarle

WIAWSNB said:

Before you remove the plastic handle, look at it carefully, and it will likely show it can only be turned one way. Once removed, the chances are the shaft can be turned either way, and actually rotated ad infinitum - it'll almost certainly be a 'ball' valve inside. So, try turning it the 'correct' way first with your spanner, but you should be fine trying it either way.
With the handle off, look for signs of scale on the shaft, which would indicate it's weeping slightly and this scale might be why it's reluctant to turn. Wipe/brush any off.
But almost certainly it will release and then turn smoothly given enough 'force'. Hold the valve firmly in one hand, and turn t'spanner with t'other.
A very good way to apply strong pressure in a 'controlled' manner is to try the spanner or wrench on the spindle in a number of directions, until you find one that has the spanner handle in a similar direction to the actual pipe, but not quite in line. Do this so that to then turn the spanner to be fully in line would be to turn the shaft in the desired direction. Make sense?!
Ok, now grasp the pipe and spanner in one clenching hand, adding the other hand over it if needed, and just squeeeeeze to turn.

Thanks for the advice.
As they have only just moved in, and only need hot water at the moment, which is working, I will leave it a couple of weeks before attempting any heroics ( and make sure I know where the stopc**k is first !)