primitives discuss rehabilitating an old water-heater

[franksolich]

http://www.democraticunderground.com/1158910

Oh my.

Robb (34,635 posts) Profile Journal Send DU Mail Ignore

Rehabbing an old hot water tank

I've picked up an old 80-gallon stone-lined high-temperature solar hot water tank -- the kind from the 80s with the copper heat exchanger built-in. Don't ask me how I got it out of that guy's basement. "Sturdy" would be the delicate way to describe the tank's weight. 

There's some corrosion on the connections... I'm thinking I need to replace the nipples and drain valve at a minimum. I know there's a de-scaling product out there that's nice and toxic; anyone know if that stuff will damage the copper coils, or if it's OK?

jeff47 (3,649 posts) Profile Journal Send DU Mail Ignore

1. No idea if this applies to this kind of piping...

...but on copper potable water pipes, you don't want to remove the "rust". It's a thin layer that's permanently stuck to the metal, and keeps the rest of the pipe from rusting. (As opposed to iron rust, which flakes away and exposes new metal).

So in copper potable water pipes, the inside of the pipe quickly rusts, but it stays there. Removing that rust makes the pipe thinner, and the newly-exposed metal rusts again, resulting in a thinner pipe.

However, this isn't a potable water situation, so I don't know if the same applies.

If it's just build up from minerals in the water, soaking in a relatively weak acid should dissolve those minerals quickly without harming the pipes. Think vinegar-level acidity, but you'll probably want to mix it up from a cheaper acid, such as muriatic. Too strong of an acid solution will indeed eat the pipes.