9100DN OWNER wrote:
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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?
Cold storage tank in loft with it's outlet some 600mm above the level of the
loft floor. The outlet pipe drops to the loft floor, runs two metres
horizontal and then drops through ceiling, then 1.5 metres drop to the
bottom of the hot water tank. There are two pipe bends and a stop valve and
two tees in the run one for the boiler and a final one for a drain. Remove
stop valve it is opening fully with a small amount of gunge. Clean and
replace in system
Is there much difference in behaviour if you almost close the valve in
the pipework feeding cold water to the bottom of the cylinder?
From the top of the hot water tank the pipe work goes horizontal say 400mm,
90 elbow and rises say 500mm then through ceiling. ( That 90 elbow between
the horizontal and vertical pipe had gunge in it now cleaned but I'm scared
to remove top connection from cylinder as I may rip the top of the tank it
is ten years old.), then runs some 10 metres horizontal. then down through
ceiling two metres to the bath. On the way it goes through 3 off 90 elbows,
two 90 bends, a tee for the overflow and then gets to the bath. All these
pipes are 22mm.
Can anyone advise if this run is just too long and complicated for a gravity
system to run properly. I realise that a nasty old storage tank and steel
boiler are not helping either.
Is it a hard water area?
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 :-)
Can you cut the pipework (assuming it's copper not steel) close to the
cylinder connector and investigate?
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