1canhelp, can you tell me where it states that you CAN use 6mm2 earth on a gas installation please. i would like to forward that onto my assessor. obviously you know everything about everything so this shouldnt be too hard for you.
from a foot pump it shoulnt take many pumps to get the vessell up to 1 bar from flat, so its either your vessell or your pump which is knackard, if you completely remove the vessell and then pump it you will soon see.
The valve in front of your cylinder is a bypass valve, its looks like your system is a 'y plan' so providing you have atleast 1 rad with no trv this should remain closed.
You may want to jump in the loft to check your f&e tank (the small one) to make sure its full, you may have a stuck ball...
Right the pump is actually under the floor boards, that picture is a bit confusing!!! on the zone valve there is a little lever on 1 side when the heating is on can you move the lever with no resistance?? (checking to see if valve is opening)