Brown hot water

[Hooo]

Help!

I've just got home to find my hot water is brown. It looks too murky to have a bath in, and if I leave it it eventually settles to a fine dust at the bottom.
The cold water is fine, even after heating in the kettle, so it doesn't seem to be a contaminant in the water supply.
The hot water system is thermal store system, less than 4 years old. It's a big vented cylinder with separate boiler and hot water coils. The hot water coil is at mains pressure, so it can't be the cylinder leaking into the tap water - if the coil had failed it would be going the other way and coming out the overflow.

What could it be? The only thing I can think of is the pipes disintegrating from the inside, is that possible?

 

[dreadnoughtheating]

just which make and/or model of thermal-store is it, and we'll go from there, shall we?

DH

 

[Hooo]

Thanks for the quick response!
It's a Gledhill Torrent solar RE 280. The solar coil is currently unused.

 

[dreadnoughtheating]

Do you have a separate feed&expansion cistern in the property? (you have mentioned a 'vented' cylinder). If yes, have you taken a look at it to see if it is filling upwards from the cold feed pipe?

I have to say, with my (thankfully limited & sad) experience of gledhill 'quality' my money is still on a pinholed coil.

if you look here http://www.gledhill.net/building-products/downloads/torrent-solar.pdf you will see a difference internally between sealed/unsealed.

Gotta say, the diagrams do show a vessel partway along the hot-water coil, never having stripped one down, unsure as to its purpose (mini expansion vessel anyone?)

DH

 

[Hooo]

I've just a look in the F&E cistern, and the water in there looks like it hasn't been disturbed in years. The level is below the overflow, and the end of the vent pipe that comes from the top of the cylinder is bone dry. It doesn't look like the cylinder has been flowing into the expansion tank from there.
The expansion tank for the cylinder is also the F&E tank for the heating, by the way.

 

[Hooo]

I've just had a look through the documentation that came with it, and there's no mention of the vessel partway along the hot water coil. It's in the diagrams, but it's not mentioned in the text.
I'm probably just displaying my ignorance here, but I can't see how it can be a hole in the hot water coil. That coil is constantly at 3 bar, and the only pressure in the cylinder is the 60cm of head to the F&E tank. So if there was a hole, water would be coming out, not going in?

 

[dreadnoughtheating]

Well, looking at it from here, apart from metalfilings in the blending valve finding their way into the hot-water to taps, its got me beat.

BTW, have you tried running the hot-taps continuously with the blending valve set to max temp? does the murkiness dissipate?, conversely, what happens if you set the blending valve to min temp?

DH

 

[Hooo]

Hold on a min, and I'll give it a go...

 

[dreadnoughtheating]

C'mom, C'mon Man, the plumber is on Friday night call-out charges.....

£75 ph +VAT and counting. (read my small print)

DH

(tony @ agile charges £84 for diagnostics, so I'm well cheap.....)

 

[picasso]

You might have disintegrating iron pipes on the incoming main

 

[dreadnoughtheating]

Picasso, he had said that the cold water was fine, but Hey, whatever....

DH

 

[picasso]

calm down, jesus,,, I missed the bit about the cold being clear

 

[Hooo]

I think you're onto something!
I can't adjust the blender while watching the water - it's up a ladder in the loft.
I turned the blender up to max, then went down to the bath and put the hot tap on full. It was steady brown while it cleared the pipes, then there was a slug of much darker brown, and then it was much clearer.
I turned off the tap, turned the blender down to min, and ran the water again. The water gradually got clearer, to the extent that it was only slightly murkier than the cold tap. I suppose this could be just residue in the pipes.
Then I left the tap on with the plug in, and turned the blender up to full and back down to the preset level. When I looked in the bath, the water was clearer than before I started, but still a bit brown. There was also some black bits in the water, lumps a few mm across and crumbly.
Could it just be a build up of crud in the blender, or is the blender disintegrating?

 

[Hooo]

@picasso
I did have disintegrating iron mains, but they got replaced with nice new plastic before the new plumbing was commissioned.

 

[Hooo]

I've just left the hot tap running and turned the blender end to end a few times, then reset it back to normal.
The hot water is fine now. Maybe very slightly brown but I can barely tell the difference between the hot and the cold.

Thanks dreadnoughtheating, I owe you a pint if you're ever down in Sussex.

My only question now is whether that's just something I have to do every now and again, or if it's the valve on its way out. I'll get on to Gledhill on Monday and see what they have to say.