Hi All! I have posted before about the water hammer noise in our home (started with one toilet, then both, then the clothes washer), and the noise has been getting progressively worse. Thought about just buying a water hammer arrestor, but since the sound is getting progressively louder, and after some good advice here, i am looking at the pressure regulator (PRV)at the front of the house . Incidentally, we don't have an expansion tank in our southern California home built in 2002, but the inside plumbing is all a PEX system. Put a gate water pressure gauge on the water spigot just, which is just before the 3/4 inch pipe goes into the house. Here is where I am a bit confused: What exactly should the water pressure be at?? Some say 30 to 50 PSI, some say 40 to 60 PSI. A few you-tube videos made by plumbers say 70 or even 80 PSI is OK?? So which is it? In our case, I am getting a base pressure of 70 PSI (black needle), and the red needle (MAX pressure) shows 100 PSI. My understanding is that the black needle shows the static pressure, and the red needle shows the most the water pressure PSI has been since it was last reset - Is that correct?, If so, is the fact the the max pressure is 100 PSI, even if only for a short time, does that mean there is a problem with the water pressure? Or is it normal to have pressure spikes and that i should only care about the base pressure? Finally, if the consensus here is to adjust, and if need be: to rebuild or replace the valve, (Watts LFN45B), how do I do that? I know to adjust the pressure (by screwing in/out the screw), but how do i open up the valve to rebuild it. The rep at Watts gave me the part number (0006960), which doesn't include the diaphragm or big spring, just a black plastic thing with a screen on it, along with two o-rings. However, I don't know if there is a rebuild kit that replaces all the guts inside. Does anyone know if there is one? Let me thanks in advance to all who offer help or advice.