Ink Black Radiator Water

[Oddjob]

Hello all, I have just taken the bathroom radiator off. The water inside was ink black.

Does anybody know why this is or if it points to anything? I assume it is corrosion.

Thanks

[Invisible Man]

I have seen plenty of ink black water in houses I have bought. Suggest you get something to flush the system with and a corrosion inhibitor (or whatever they call it in diy shops at present). The last lot I did I had to leave the flusher in for a few weeks I believe. Not sure whether you will have to run the system hot which might not be ideal in the current warm weather.

[Gel]

Better than having rust coloured water!

[Palindrome]

Afraid not..

It is probably very fine particles of black iron oxide (Fe3O4). It is formed preferentially to "normal rust" when rusting occurs quickly under water. It may be due to the presence of corrosion cells, pit corrosion or an impressed current.

There is an easy way to test - take the liquid and pass it through a very fine filter paper. Repeat. Allow the paper to dry. Apply a magnet. Black iron oxide is magnetic and the paper will stick to a magnet.

The good news is that it doesn't expand and block pipes and tubes, as normal rust will. The bad news is that it used to be metal... If it is all coming from one spot, which is distinctly possible.. then it could eat through a few mm of steel in next to no time..

No, or very old, corrosion inhibitor in the system, perhaps?

[Andy Champ]

That was last week :(

The black is an iron salt. Flush it, then stick some Fernox in it.

Andy

[cj]

Hi You think right,it is a form of corrosion but in most cases not a problem. A chemistry geek friend did tell me once but all I recall is its a combination of the copper reacting with the chlorine in the water,the iron in the radiators,pump and valves and the cast iron of the boiler (if you have a cast iron heat exchanger). A good flushing with clear water and a dose of 'Fernox' or similar will soon shift it but here's the kicker .. some 'fernox' types turn the water Black. One things for sure Keep it of the carpet its a b*^^*r to clean.

CJ

[Ian_m]

Wrong....copper oxide and the "gel" sometimes found blocking radiators is a copper hydroxide complex. Both are irritants.

[Andy Champ]

Ian, I'm puzzled. Which part of my post is wrong?

Andy

[Ian_m]

The black bit. It is copper oxide not iron oxide.

[Andy Champ]

Ah. I admit I've never tested it, but others have posted up Iron oxide many times. Of course if it's true about the magnet...

Andy