Well, I finally got around to disconnecting the pipework from the top of the
tank the other day and tried syphoning the water out with a hosepipe to see
if I could drain the mud from the bottom of the tank.

This didn't porduce the expected results so I assume that the hose was
coiling up in the tank. I found a bit of 15mm plastic pipe which made a
perfect "dip-tube" to reach to the bottom of the tank and started syphoning
again.

Again, there was hardly any discolouration.

Having drained of a good deal of water reassmbled everything and
repressurised the system, I just flushed all the hot taps for at least half
an hour each.

This produced some crud briefly but then the water ran clear.

Despite all this, I'm *still* getting some discolouration when first
openning a tap in the morning (shower and bathroom sink) . It's probably a
bit less marked than it was though. I think just *has* to be silt in the
pipework but it's proving very hard (and slow) to shift completely. :-(

I guess in time it will just clear up and I suspect it's the higher flow
rates induced by having a mains pressure tank now that is shifting all this
old crud but I'm amazed at how persistent the ruddy stuff is! The tank was
installed over a year ago and the problem has been going on all this time.

Tim



Tim+ wrote:
We have a pressurised HW system (an Albion Ultrasteel cylinder) with a
external 18L expansion vessel.

For some time now we've suffered from intermittant dirty water
supplies which we suspect was due to a problem with our water mains
further down the street (as manifest by the major blowout recently
http://i1052.photobucket.com/albums/...k/da49f87f.jpg )

Anyhow, our water supply (or at least our cold water supply) has
cleared up but we continue to intermitently get dirt in our HW supply
which I've been putting down to a HW cyclinder full of silt. If no
water has been drawn for a while (like overnight) the HW is visibly
stained.
Today I thought I'd try and drain down the HW tank using the drain
cock to see what the water was like nearer the bottom of the tank
(expecting it to be really dirty). I filled half a bucket and poured
it into our sink and this is what it looked like
http://i1052.photobucket.com/albums/...EDFA1D3991.jpg
As you can see, only very lightly stained.

It seemed a bit pointless to carry on draining the tank so I
repressurised and and refilled the sink from the tap with this result.
http://i1052.photobucket.com/albums/...ED925ED3B6.jpg


What I want to know is, where the feck is all this crud hiding?? This
always happens if I depressurise and repressurise the tank. It's had
a new pressure vessel about 3 weeks ago after the diaphragm failed in
the old one so I know it's not the pressure vessel that's full of
crud.
As I say, our cold supply seems okay but I'd really like to flush all
this crud out of our HW system but I'm mystified why water drained
from the bottom of the tank is so much cleaner than what's coming out
the top.
Tim