Yes you are right. The average guy like me has no understanding of pressurised systems. The pipe drips on all 6 houses constantly.
We now have some idea why.
Thanks again
Yes it is a Megaflow. There is a label on it which you can read once you empty the airing cupboard and climb round the side of the cylinder.
Followed the instructions and it gurgled for about 40 mins. All seems well Thank you all.
Will pop round the neighbours now as they all had water...
I have a mains pressure system with a large cylinder in the airing cupboard. It is fitted with a vent valve on the side which is constantly letting hot waterout of the cylinder into an open cup. In the winter the pipe which runs down the side of the house froze and water back filled the pipe...