I'm wondering if anyone has had success or tried to replace/retrofit a line set which was originally run behind the interior walls of the house. About 6 years ago, I had to have the line set replaced in order to get the full warranty for the replacement heat pump from Ruud. The installers ran the line set on the exterior of the house to save time/money and ran it up through the attic gable vent. The look has bothered me ever since and am now contracting someone to replace it on the inside. They've told me that they would run it from the attic down and it would be exposed inside in corner (in closets/pantry,etc.) Although this is better than it exposed on the outside of our brick home, I'm wondering if it's possible to drill new holes from the attic down through the studs and maybe place some kind of PVC pipe or conduit running down through to the bottom floor to help guide the copper set behind the sheetrock and facilitate any replacements in the future. I"m even Ok with cutting some drywall inside the pantry to guide it/drill holes and then put an access cover over it. This to me would look better than a pipe running through closet/pantry. This is approx. a 25' vertical run. The line set is 3/8" x 7/8". Thanks for any suggestions.