Onetap wrote:
On Friday, August 31, 2012 2:48:13 PM UTC+1, 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

The internal coil has probably failed; the crud is from the heating system.

Nope. It's a sealed CH system. No pressure loss

Tim