I have a 1.5 inch PVC pipe inside my wall. The PVC serves no purpose and is open at both ends. I want to run 3/4" PEX though the PVC. Do I need to be concerned that the PEX is not tight in the PVC? The distance is about 20 feet. Any concern that the PEX is not snug inside the PVC?
You should be fine. We sleeve PEX piping when running it through foundation walls or where we are concerned about it being damaged. The PEX does not need to be snug in the PVC. If you experience water hammer it could cause the PEX pipe to move around inside the PVC and I would recommend addressing that if it is an issue. You don’t want to allow the pipe to slam around in any case.