9100DN OWNER wrote:
Now test hot water taps again. Wash hand basin about Ok but not as good
as before boiler replacement! Kitchen tap not wonderful but it is a mixer
tap and may not be suitable for a gravity system. Bath tap flow very
poor. So go into loft and the bath tap appears to start by draining the
overflow pipe

how do you know this?
The friend is a lady and she said so!!! for drop in performance recently.
Otherwisw this is from getting friend to open the hot water bath tap when I
am standing beside the cold water storage tank.

Sorry, I meant how do you know the bit about draining the overflow pipe
(since you can't see into it)?



Is there much difference in behaviour if you almost close the valve in the
pipework feeding cold water to the bottom of the cylinder?


I will try that tommorrow. I know it stops the cylinder filling when closed.


Is it a hard water area?


No, very soft water area, Aberdeenshire

I've seen an almost-blocked outlet from a cold water tank in a soft
water area (mid-wales, Elan Valleys supply, so I supose it must have
been reactions between different metals rather than anything in the
water itself). I wonder if the same could happen at the hot water
cylinder outlet?


Could it be that the top outlet of the hot water cylinder is scaled up and
letting little water through? That could explain the vent pipe draining
and air consequently being drawn into the system. Also, since it's about
the one part of the system you haven't opened up to check, Sod's law
dictates that that's the culprit :-)


When I last filled the system with the hot water cylinder say 10% full, I
turned on the washing machine link and the water was comming in there at
what appeared to be with some force.

Though with mains behind it you'd expect some force, even if the actual
flow wasn't up to much.