opinions always welcome. Wilkins sets theirs to 50 psi. The final PRV PSI is an arbitrary thing to the individual household based on stories, etc.. Wilkins, and I think Watt too have graphs where the GPM going thru the PRV can be compared to pressure loss across the PRV. Meaning that a PRV set at 50 PSI will drop up to 12 - 17 PSI depending on load. Because here water at say 40 PSI is quite weak and the washer takes forever to fill, that was actually the basis of my original question that started this thread - do I set it to say 60 and expect it to be 50 on demand etc. But in spending quite some time reading Watts and Wilkins documents there are a couple places where it says the PRV's are set closed. The second part of the equation was where to set the Expansion Tank - at the closed PRV value or the average operating PSI under load, The answer was to match the PRV closed value. Then there was a pissing match over whether to remove the expansion tank and drain it to check it, or to just turn the water off and open a faucet to relieve pressure before checking it. Some were concerned that the water in the pipe would greatly skew the pressure. No need to discuss all that again.