Once again you responded by sticking to the simple easy solution of an easy
problem and completely ignored and tip toed away from the initial question
(and my questions) that started this whole discussion. First, to address
your comments: You must be a very unusual plumber--I don't ever recall one
that actually measured anything--typically, they replaced or cleaned out,
nothing scientific or mind boggling.
Thermal expansion: Your comment:*** "The thermal expansion causes the
spike in pressure equally throughout the system as long as the PRV is
working and is closing the system.***
Dribble, and it surely indicates that you really don't understand what
you're talking about. Think of thermal expansion as it applies to the
cooling system in your car. As the coolant temp increases, volume increases,
pressure increases until it gets to the radiator cap setting and then the
coolant spills over to the expansion tank. No spikes in pressure--- it
increases along with the temperature. With the PRV and all faucets closed
you have a volume of water trapped between them--aka, a hydraulic lock. As
the temp is increased, up goes the pressure-what do you think would happen
to your piping if there was no escape route via a relief valve built in to
the PRV or the water heater T&P valve? No different than if the water
froze--something is going to break! Obviously, an expansion tank provides
the room to accept the volume increase--that's why it is recommended. Not
rocket science. Now once again--would you just stick to the subject--Why do
you think there is a flow of water that lasts for approx 10 seconds when the
faucet is opened? What do you do to resolve it?
Oh yes--you guys do make BIG bucks and in many cases it's justified. One
should get paid not only for the actual work but for what he knows. But do
you really know what BIG bucks are? Think of the most expensive thing you
ever worked on or charged. I worked on a product that sells for 2.5 million
dollars. At times I've had to make a judgment call on resolving a problem
and replaced a component(s) worth about $50,000 a piece. Early on in the
development process (and the need to resolve a problem) required the use of
a facility that, with a discount, cost $10,000 an hour with a 10 hr.
minimum. Do the arithmetic, it cost $100,000 a day, sometimes for 2-3
months at a time. Finally, our product ended up as a key component of a
$32,000,000 machine. In the troubleshooting process there is a difference
between shot gunning and selective replacement of components. At times,
the least likely of two components might be replaced first because it might
only take 1 hour vs. 8 hrs. for the most probable one. Better to waste an
hour than maybe 8 hours. Sorry if I got carried away--didn't mean to.
MLD


wrote in message
oups.com...

MLD wrote:
wrote in message
ups.com...


"I had a new hot water heater installed, and shortly after that, it
would discharge water."

why?
1) pressure
2) temp
3) faulty T&P

How are you going to tell if the discharge is either a faulty T&P or
due to pressure, you can't without a gauge.

How are you going to tell if the pressure is from a bad PRV, you can't
without a gauge.

You can watch the spikes on a gauge and even verify thermal expansion
is happening with a gauge.

Only an idiot would come to a conclusion without facts, at the
expense
of a homeowner.
kenny b

Good questions, but a very feeble example. First of all, most home
systems
don't have a point of entry where a pressure gage can be installed.Where
would you put one without taking anything apart?

Laundry tray, hose bibb, washing maching valve, the water heater drain
valve itself.
A plumber would know this.


Obviously, one can rule out temperature very quickly--not hard to
measure or just shut off the water heater and see if the problem
recurs.

Thats why it was listed but I responded with pressure.

Then there are times when it is just
as efficient and cost effective to substitute as it is to try and
troubleshoot.

Really, Most professional plumbers not only want to know but need to
know what is causing the problem before repairs are made. Someone's
paying you for a professional opinion and your guessing. I guess you
just defined your self.

As far as the rest, I won't waste my time. A real plumber would have
had the problem solved and repaired on the first trip at a fair price.
Hey thats why we get paid the big bucks, right.

You can see the real plumbers here responded with thermal expansion, a
gauge would prove that in seconds if the system was closed. The gauge
would also prove the PRV was working.The thermal expansion causes the
spike in pressure equally throughout the system as long as the PRV is
working and is closing the system.
We're not building a watch here, this is basic plumbing.

Yes an expansion tank is probably needed to solve the problem, but that
should of been confirmed from the begining. Instead his plumber
followed your play book and changed the PRV twice.

kenny b


In this case, the T&P first since it is the easiest to remove
and it is also the least expensive. Maybe you can watch spikes on a gage
but
in no way are you seeing what's actually happening. Have you ever
recorded
large amplitude, high frequency pressure pulses with and without a gage
installed in the system? I have!! First of all, a gage does not have
the
capability to respond to a transient pressure pulse; it tends to act as
an
accumulator. The net result is that it attenuates and dampens out
pressure
pulses in a system. Finally, you didn't address the prime topic of
discussion which is why there is a high flow for approx 10 sec after
opening
a faucet. Just use some common troubleshooting sense------- If you
have a
normally functioning PRV how can a defective T&P valve cause high flow
out
of a faucet for 10 secs? Flow is a function of Supply Pressure and
system r
esistance. The only component that is responding to the city supply
pressure
is the PRV. It has to reduce that pressure to it's set point (household
pressure) and keep it at that value independent of the flow demand.
The
slower the PRV responds, the bigger the variation in household pressure
and
the more the variation of flow out of the faucet. In this case a gage
would
certainly show a gradual reduction of pressure over a period of 10 secs
pointing to the PRV.
MLD