I've looked around the intertubez, and think this MIGHT be galvanic corrosion, but there was NO sign of it when we bought our 1930's house 5 years ago. The Taco pump WAS replaced 3 years ago (that's when I learned about airlocks, too!)... the old one had no "corrosion" issues, the new one clearly does. Did the plumber miss a step in terms of separating the connecting surfaces with something? I recently replaced the pump servicing the upstairs rooms (again, user error, based on faulty instructions), and the piping on either side of the new pump appears to be starting to corrode as well.

The auto-pressure valve on the cold water inlet to the heating system has never been touched, so why it's doing the same thing is beyond me at this point.

IS this corrosion, and if so, how can it be prevented/cleaned up?

Cold water inlet - blue buildup on bottom [Taco pump - buildup on hot side of pump[2] Taco pump - buildup on cold side of pump

  • Well it's definitely corrosion - that's the color you get when copper oxidizes: google.com/search?q=oxidized+copper&tbm=isch ... why it has happened so quickly, I do not know. – CactusCake Apr 13 '17 at 20:14
  • Is that a cold water pipe? If there is moisture on the outside in contact with the copper and steel bolts galvanic corossion can happen very quickly. Cold water pipes some times collect condensation and that can cause the corrosion when in contact with other metals and or excessive flux residue. Was thinking about condensation collecting and dripping because there is some buildup on 1 side of the brass ball valve just below. – Ed Beal Apr 13 '17 at 22:14
  • Thanks for the input... so, first thoughts are just to retighten all the bolts, just to make damn sure the cold water is staying inside the pipes. There's no sign of dripping, but if it IS a slow leak, I do have a dehumidifier running at all times down there, so that might account for both the lack of obvious wetness AND the deposits. – Dustin Kreidler Apr 17 '17 at 15:35

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