Is it truly a concern that the hot water drained would cause problems with potential melting of the PVC joints?
There is access in the attic to replace a portion of the PVC up to where it goes into the wall. If I had the accessible PVC replaced with copper into a holding tank that subsequently connects to the PVC, would it be sufficient to cool the water enough?
Is there a flexible hose option - similar to hot water hoses that connect to washing machines?
I want to avoid any interior work where the lines go through the wall and drain outside.