2 biz if you don't mind me asking, how did you make the caps that cover the PVC?More options for you! I did my outside truck bay using this method...The cap I made just snaps into place. In the attic, I cut a 1.5"-2" wide strip down the entire length of the 5" pipe. Right through the connections. Makes for easy install of any tubing or replacing anything in the trough. To insulate, I cut 8' long strips of 4" insulation and stuff it in the pipe to seal it up. No freeze ups since making the change. When I bought the wash, the pipe was solid with only openings above each bay! No insulation...PO complained of freezing up every winter...For the life of me I don't know why the PO's put up with that! Pulling new lines down the entire length of pipe must have been exhausting too!
It looks to me like the thin wall 4" sewer pipe.Is it just regular PVC? What size? It looks very thin.