Posted by PAUL M. DERY on June 16, 2002 at 15:29:54:
New condo association in beautiful Naples, FL is
having a rash of problems with underground copper
tubing leaks in the central air systems.Condo's
are fairly new; some still in construction. Age
of piping on discovered leaks varies from 18 months to 3 years. Very slow leaks occurring in
copper tubing. Owners don't know their system is
leaking until system fails to produce cold air.
Have found the following: copper tube type is
unknown. Suspect tube leaking has approx. 1/2" OD.
Tubing has developed random green bands externally
Tubing enters a 4 to 5" flexible corrugated duct
which runs under concrete slab to reach destination. Leakage, using a sniffer, is detected
where the tubing enters the duct. Problems are:
Tubing should be ASTM B280; verified by ASTM and
Copper Development Association. Mouth of duct is
sealed with polyurethane foam sealant (PFS). MSDS
for PFS says to avoid contact with all soft metals
including copper. A strong chemical reaction occurs when PFS is released from its "spray can".
It will burn your skin. The mouth of the duct is
buried under topsoil and pine needle mulch. Suspect chlorides abound in the soil because coral, crushed and stone, along with sea fossils
are prevalent in the soil. The tubing is also
flanked on both ends by concrete slabs. Concrete
can leach chlorides. Rainwater from the roof falls
directly upon the location of the duct mouth buried under the topsoil and pine needle (acidic)
mulch. The mulch helps to retain water in the soil. The rains are mostly downpours when they occur. So, we have some unknown type of copper
tubing being affected by water, chlorides, and PFS
Looks like a lose-lose situation.
The fix is to replace the copper lines and run them overhead through attics. There is a firewall
though. This means one compressor will have to be
relocated to the opposite end of the building and
a new concrete pad will be needed to support the
compressor. The developer says we don't have a problem with the existing copper lines because they were installed according to Code. However,
Code says to use Caulk or Tar to fill the void at
the duct mouth. Need to know what you know about
buried copper, chlorides mixed with water reacting
with the copper, and PFS. This problem probably
has occurred elsewhere. Looks like a class-action
lawsuit. Any thoughts?

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