On 17 Nov, 19:59, Peter Johnson
wrote:
On Mon, 17 Nov 2008 16:43:25 GMT, "BigWallop"

wrote:
This system is cold water storage tank fed? *The cold water tank is in the
loft? *The hot water cylinder is one floor below the cold water tank? *The
shower room is on the same floor as the hot water cylinder?

If the answers to these questions is yes, then make sure your cold water
tank is filling properly, because the actual pressure for this system is
coming from the highest point in the cold water storage tank.

If you answered no to any of the questions, then can you explain what is
different?

Your analysis is correct. I will investigate the tank in the loft
tomorrow. Thanks.

I had to resolve a not dissimilar problem in my daughter's house some
years ago. I never did see what was causing a blockage in the cold
water feed to the hot tank, but I had to back flush the system with a
hose between the the mains tap and the hot tap, having drained down
the cold tank first. That didn't work initially but loosened up
whatever it was for the problem to disappear an hour after I'd given
up!!

The suggestion was that the blockage was caused by a slime film build
up.

Rob