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line set leak at contact with mineral wool insulation

Where there was direct contact with the line set by mineral wool blown-in insulation we had had two leaks. Nowhere else in the 30 foot run that has the foam factory insulation has had an issue. This is a 2 foot foot long section and has leaked 2 times prior.

Is there an issue with cold moist copper and contact with mineral wool? thanks....


  • mattmia2
    mattmia2 Member Posts: 9,942
    The ultimate issue is that the copper is paper thin so the tiniest defect causes a leak, but the mineral wool might be slightly acidic.
  • scottx
    scottx Member Posts: 1
    Just did a little more digging. Mineral wool has a high Ph. Too acid or alkaline seems to be a problem with copper, probably other metals too.
  • Jamie Hall
    Jamie Hall Member Posts: 23,635
    Combination of the mineral wool and it's holding moisture next to the copper. The lineset should be sleeved through there.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • pecmsg
    pecmsg Member Posts: 4,949
    Why was the suction line N O T insulated with the insulation ends sealed?