I'm installing a 5 gallon Thermal Expansion Tank in my home. I'm also installing a PRV set at 50 PSI. The expansion tank states that it should be pressurized at 2 PSI below working pressure in the line. Is this as simple as pressurizing the tank to 48 psi before I install both items and that is all I need to do? Also (and this may be a dumb question), do PRV's have anything "loose" inside? There is something that rattles on the inside. It sounds like it is only one thing that is rattling around the inside. Any other help or pointers on this would be welcomed as well. Thanks, Craig

I have always been taught and have always recommended that the air pressure in the expansion tank be at or slightly over the working pressure of the system. That way you only have water entering the tank when it is expanding and increasing the pressure in the system. Otherwise, it becomes water logged and doesn't give the expansion anywhere to go. As far as the rattle in the PRV I don't recall ever hearing that before but maybe someone else will have more feedback on that.

Does PRV have a lever on side of box. If it does, u may be hearing it rattle.When lever is moved, it closes contacts on PRV.

Chuck

My apologies, the rattle is in the thermal expansion tank, not the PRV. The PRV is a standard old Watts 25aub.