On Fri, 25 Jul 2008 08:39:50 -0700 (PDT), JayN
wrote:

So far I've had the gauge connected for over 12 hours. I've still yet
seen the red memory needle get above around 98, and it didn't stay
near there long. The pressure is probably averaging 85 or maybe upper
80s. It's higher than normal, but not extraordinarily high. I'm
wondering why they can't install a Watts PRV valve that allows
backflow rather than bothering with an expansion tank? According to
Watts the ones with a B suffix in the model number allow backflow from
thermal expansion.

Totally pointless. The backflow may be prevented at your meter,
either now or in the future. Put in the expansion tank; take it from
somebody who's been there and had the leaks.