Loss of water pressure

I have a gravity fed hot water system. Until recently it had a health

system presssure. No changes have been made to the system and no recen work has been carried out. Pressure has dropped off to the point wher it can take 20 minutes to run a bath. There has been a correspondin drop (although not quite as significant) in cold water presure Pressure starts good and tails off as if a down pipe were emptying bu not being backed up.

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

-- kipper

Is the hot water tank open to the atmosphere? If not, I assume there must be some kind of vent to allow air into the tank as hot water is drawn off. Vent clogged?

By chance, is this system in the UK? If so, the UK group may know more: UK.D-I-Y

Jim

The header tank is open to the atmosphere.

It is in the UK. Will try UK DI

-- kipper