Quote Originally Posted by ballvalve View Post
I really don't get the 150 psi rating on the T&P valves. By that time, the old toilet supply hose blew and ruined your wood floor.

I like Watts pressure relief valve made just for water heaters, as backup to the stupid t&p's and exp. tanks that blow silently and plug your fixtures with gunk.

The 150 PSI rating is to protect the water heater from pressure higher than that point, which can damage the tank. You MUST have "T & P" because you must also protect against the T.

All components in your plumbing system, including the toilet and its supply lines, are designed for a test pressure of 150 PSI. The normal operating pressure should not exceed 80 PSI, and your house should be built so that is does not ( PRV installed if necessary). There is no code requirment to PROTECT your house should the pressure go higher. The expansion tank will help to keep the pressure much lower than that 150 PSI number.
A bypass on a PRV will only keep the house pressure from exceeding the street pressure. That is of little comfort is the street is well above 100, maybe above 150.

I don't understand about the silent blowing and the gunk???????