DIY Doctor UK DIY Forums

I'd be grateful if anyone has any advice on the following:

I bought my house from new, just over 4 years ago. Yesterday, one radiator sprung a leak and the liquid that came out was a really dark colour.

On inspecting the header tank in the loft, it contains slimy deposits, like algae, and is obviously dirty, although fresh water flows in.

I'm concerned that as the house is so new, and the header tank water is as described above, does this suggest that a rust inhibitor has never been put in or can this happen anyway?

From the leak on the radiator, it appears that part of it has been corroded and another radiator looks to be going the same way.

I've got someone to help rectify the problem, but I'd be grateful if anyone could let me know whether there is a reason for what's happened in a relatively new house and whether the underlying cause could be with the original installation?

Many thanks, Mark

"Peter-the-plumber" has suggested that some of my history of sludge problems blocking radiators, has been likely down to plumbers not bothering to add the anti-corrosion inhibitor chemical;--- that would cause dark particulate iron oxide (magnetite, which can be separated out in a magnetic filter, when power-flushing to clean the whole system). Air ingress from leaky joints/couplings/permeable plastic piping (no longer in use), is known to create brown slimy algae, even to the extent of it accumulating in the header as "cumberland sausages". I have had auto-bleed valves fitted to the bleed-point of the tallest upstairs radiator, and also to a 22 mm pipe reaching above the boiler input to the indirect cylinder.
A power-flush costs about £600, but all air problems need to be adressed

if it is a new house there wont be too much sludge build up to need a full powerflush. they probably didnt use an inhibitor or flush out the left over flux from the installation which is causing your problems. stick some x400 in it leave for 4 weeks then drain and fill a few times then add x100. but damage to existing rads and maybe even boiler is probably allready done

Thanks for your responses, they are really helpful. I contacted the building company and they are sending out an independent plumber next week to carry out some tests on the header tank water.

Thanks again,
Mark