I'm switching it up a little bit this week by going to the plumbing side, which many of us mechanicals do often.  Tim Totten from PVI and I discuss instant vs. storage, sizing, tank construction, water treatments, legionella and their electric water heater that I'm using more of with the electrification of California.  I highly suggest looking into the PVI Durawatt and the Aquaplex construction.  It blows me away how short of a life span tanks actually have and how PVI will offer up to a 25 year, yes 25 year warranty.