Hi, i'm new here and i've just read this post. FWIW: in Bay Area Ca. we installed the Watts 210 in the T&P port using hard pipe on either side of the W210 and flexi-connectors at the gas valve and the isolator. W210's were always installed with a Watts 530C calibrated PRV installed on the water service at the hose bib, just before the service entered the property. The W530C was to control the pressure of water entering the W/H, of course. No conventional T&P was installed, and the W/H was typically a "Stubby" - apparently, Stubbies are no longer made.
