Do you have sufficient air inlet to the storage tank?
RJ
"kipper" wrote in message
...

I have a gravity fed hot water system. Until recently it had a healthy
system presssure. No changes have been made to the system and no recent
work has been carried out. Pressure has dropped off to the point where
it can take 20 minutes to run a bath. There has been a corresponding
drop (although not quite as significant) in cold water presure.
Pressure starts good and tails off as if a down pipe were emptying but
not being backed up.

All valves feeding the header tanks seem to be open and depressing the
ballcocks results in appropriate water flow into the tanks.


--
kipper