On 2/5/2017 3:14 PM, Bobby wrote:
replying to Chris Hill, Bobby wrote: No hard and fast rules. I have
one in this house, never did in my old one. My water pressure is 70
psi. When the water heats and is not running, pressure will go up to
100 psi. At that point the PRV will weep a bit. It would leak
about a pint to a quart in a day depending on use. If you have
any leak, put in the expansion tank. If no leak, not to worry,

When I moved into my house there was an expansion tank. When I
had the hot water heater replaced recently the guy removed the expansion
tank. When I questioned this he said the new water heater was designed
to not need one. He was apparently right since the pressure does remain
constant throughout the cycle.

BTW I'm late to the thread so please excuse if already covered.