Question: Been waiting 2 weeks to hear from US Products, wonder if you can answer my questions please. To what pressure is the heater tank tested to (psi) and What is the pressure relief set to. These are in the Pex 500. nothing in the manual, except thermal cut-out at 262 DegF.
Regards Alan

Answer: US products Heaters are designed to work at pressure below 500 psi. Safety valve is designed to open at 600 psi in the event the heater thermostat is stuck in the closed position.

Links:
Pex 500
http://www.steam-brite.com/advanced_...ywords=pex+500

US products heater rebuild kit
http://www.steam-brite.com/products-...h-p-14919.html