I second the notion that it is caused from thermal gain from heating the
water. My camper is real bad about this when I use the PRV on it, because a
PRV also acts as a check valve.

--
Steve Barker



"eastcoastguyz" wrote in message
ups.com...
I talked to the plumber and he said that about in 25% of the homes that
they install new hot water heaters, they need expansion tanks, and that
this affects the hot and cold water as well. While I am waiting for a
quote to have this expansion tank installed, I thought I would post and
ask if others have had this experience or could shed some light on it.
Does an expansion tank sound like the solution?