Underground Piping Leak?

I have a customer with a Mitsubishi City Multi system in his house. The condensing unit is located about 40' from the house and the piping runs underground. There does not appear to be a sleeve of any type and I can't even see where the pipe comes in. It just appears in the attic from inside the wall.

There's a leak in the system somewhere. We found a leak at an evap and repaired it but it's still leaking elsewhere.

My question is: how likely is piping to develop a leak buried underground with no PVC sleeve? I hate to excavate this guy's yard but we haven't found a leak anywhere else. It was put in about 5 years ago.

is possible. Were there connections made in the buried tubing? What is the Ph of the soil? Was the liquid line insulated? Did they put crushed stone or anything around the pipe? Like you, I would make darn sure the leak was underground and not in the wall before I dug up the yard. I would isolate every piece of equipment and line and test it individually.

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Originally Posted by gregp

is possible. Were there connections made in the buried tubing? What is the Ph of the soil? Was the liquid line insulated? Did they put crushed stone or anything around the pipe? Like you, I would make darn sure the leak was underground and not in the wall before I dug up the yard. I would isolate every piece of equipment and line and test it individually.

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Yes, it's hard copper and not straight so there must be some fittings. Ph will be low. Salty, tropical environment buried close to the surface. I doubt the liquid line is insulated. I don't think there's anything around the pipes except that cheap plumbing type insulation (split and glued, not Armacell). We'll be isolating and pressurizing it tomorrow to see which side loses pressure. The part from the ground to the attic appears to be buried in the concrete wall so that could be fun, too. (Concrete/block homes here in hurricane country.)