Why Are My Copper Pipes Turning Black?

Roysterama

The copper risers and returns near my 24 year old steam boiler have turned black. The risers are black around the fittings and the returns are black and scaly on the undersides (see photos)

. Is this normal? I thought the fittings and vents might be leaking but I don't see any leakage when it is running.

The boiler still works, but lately has been consuming more water than it has in past. I now need to add water every couple of days.

EdTheHeaterMan

The acid flux was not wiped off after soldering was completed?!?

Steel wool or grit cloth will remove the old patina from copper. Clear lacquer will keep it shiny.

I did that for a supply house operating display I built. It actually operated one of the air handlers that heated the office space. I think it is still operational today after 21 years.

mattmia2

the part that is crusty under the vent is because either that vent or some previous vent was spitting water. might need a nipple between the main and the vent to let the water drop out of the air and possibly a bigger vent or maybe that vent is just bad, but given that it is all copper there are likely some deficiencies in the piping.

what is that greens Sears box on the wall from some old boiler?

Jamie Hall

That black is one of the quite normal copper oxides — I forget which one. Pretty harmless, if ugly. Though I wonder if by any chance you have an oxidant, such as pool sodium hypochlorite, around?

The water usage however, is too high. You have a leak or leaks somewhere — but that isn't contributing to the black .