Rex wrote:

The water heater in my home is about 5 yrs old. It has started
clicking constantly in the last day. Seems to be functioning fine,
but has a loud, steady clicking. As best I can tell, its coming from
somewhere near the top. When the water is shut off, it stops.
In reading this group, it sounds like I may have a valve problem? It
does sound like a small metal ball bouncing around inside the CPVC
pipe.
Can anyone help?

thanks!!
Randy

It *is* a small ball bouncing around! The heater is equipped
with "heat traps". These are short nipples on top of the heater
with a nall check valve inside to prevent the hot water from
"migrating" up the pipe when no water is being used. It's a
conservation measure.

Do a GOOGLE for: "Heat Trap" nipple

Jim