On Monday, September 3, 2012 8:44:24 PM UTC+1, Tim+ wrote:
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

mmm but the HW tank is mains pressure? & the CH is pressurised by the mains through the filling loop(when being re-pressuised)?

So spose the CH should be at a lower pressure than full-on mains? If you were to reduce slightly the pressure in the CH would it magically gain pressure (overnight say) from a possible leak in the HW tank coil between the mains pressure HW cylinder and CH system?

That wouldn't explain how the crud comes back out of the CH system into the HW tank to give mucky water - but would confirm no leaks in the HW tank coil?

Jim K