I didn't know there were two kinds of Schedule 40 PVC. The wording to me seemed like cell core was something different than Sch 40, and was so eager to install didn't catch it. I decided to relocate WH to an outside utility room after learning that this WH also had an on board heater to prevent freezing. Just keeping a light on in this room will prevent freezing but that's why I decided to put it inside originally. The venting was also much easier outside with a vent terminal that's much better than two pipes sicking out the wall. I used PEX this time with curved corner braces and I can't notice any reduction in flow from the all copper set up. Both ran 2 showers and 2 faucets, maybe could do more but that was the extent of my testing for both installs. I read so many post about this heater and many others I'm surprised no one mentioned the specific PVC. Rheem water heater has been flawless though. Pleased with it now and learned a lot as that can be part of the process for first go around with something new.