: Scott Evans wrote:
: > I have a 40 gal natural gas water heater that's at least 17
: > and so is past its prime, but still heats up the water just
: > quite quickly, so there are no performance issues with it.
: > However, I've noted that over the past few years that
whenever it fires
: > to heat the water back up after hot water is drawn off for
use that the
: > water pressure in the house goes up significantly. I do have
: > pressure reducer valve at the water service entrance that
: > permit any back flow which was installed a few years ago, but
: > does not seem to correlate with the start of the increase in
: > after using hot water.
: > I do not have any expansion tank installed, but I know that
: > originally moved into this house that this pressure increase
: > present, so that's not the core issue.
: > Once I draw off some water from the pipes (a cup or two or
: > bring the pressure back to normal) the pressure remains where
: > Is this increased pressure when water's been heated a sign
: > heater's ready for replacement, or is the root issue
: > Thanks!
: Has nothing to do with the heater or its (impending) failure.
: You *must* have an expansion tank when a PRV is installed.
: The PRV might have a "bypass" port which has become
: clogged and that is causing the pressure build where
: there wasn't any initially.
: The expansion tank will solve the problem AND give the
: heater longer life by holding the pressure inside the vessel
: to normal levels.
I'd have to agree with that. The "change" could also be due to a
loss of some of the air in the anti-hammer air traps, etc.,
especially if there has been any rearrangement in the plumbing at
all. I can't recall what you call those air traps at the moment,
but often they're enough to absorb the water expansion due to
heat until they lose their air. An indicator of this would be
that the pipes also bang or make thumping noises now that they
didn't used to, or it's louder than it was.
Just my 2 cents.