We have domestic water at a pressure of about 80 psi and we
have pressurized irrigation water at who knows what
pressure. Many people connect both to their lawn irrigation
systems because they need water between the times the
irrigation system is turned off in the fall and turned on in
the spring. Note: the irrigation companies were developed
for agriculture and the timing of water delivery is based on
agricultural needs so the needs of lawns are not really a
consideration.

The domestic water delivery people are worried about
contamination of the domestic water system and to a lesser
extent the contamination of the domestic water at homes.
They would have no worry for the system if there were check
valves at each turn out.

Kevin wrote:

He does not need an expansion tank on his domestic hot water system unless
he has a circulating pump. The PRV he should install. The check valve I am
guessing your talking about is a backflow only needed on the irrigation
system
"George E. Cawthon" wrote in message
...


bud wrote:

WRONG - WRONG - WRONG !!!

I just got done fighting this same battle and contacted 10 local
plumbers
and not a single one had the correct answer ... but they all had an
incorrect EXPENSIVE answer.

The odds are that you have (or now have) either a check valve or PRV
(Pressure Reducing Valve) at your water meter. That makes your house
plumbing a CLOSED system. A water softener can also "close" a plumbing
system as they are reluctant to "backflow". A closed system does not
allow
for the expansion of water heated in your hot water heater. Since
"thermal
expansion" is a certainty when water is heated some accommodation for
the
increased volume of water is necessary (and may be required by plumbing
code in your area).

That can be accomplished by a variety of solutions. One, do nothing and
allow your T&P valve on the water heater to "burp" the excess. That's
bad
for the valve and cuts it's life. Second, install a "thermal expansion
tank" at the cold side of the hot water heater. This is costly, usually
requires a plumber, and can be a kludge as there is usually no where to
locate the tank as an after thought. Third, and a really cute answer ...
go
to


https://www.wattsind.com/watts/showp...jectGroup_ID=2
47

This is a replacement ballcock for your toilet that incorporates a
pressure
relief valve set to dribble excess pressure at 80 psi. It works
flawlessly.
Just be careful to get the correct size for your WC tank. Their docs are
vague and you must measure the height of your overflow tube from the
tank
bottom and get the valve which has a "CL" or "critical level" equal to
or
higher than the height of the overflow tube. The valve comes in 10",
11.5",
& 12.5 " overall length and is usually sold only through Plumbing Supply
Houses ... no Home Depot or Lowes. You can buy direct through the Watts
Online Store or I have found them on the net but always at the same
price.
The price is a bargain when considering you don't need a plumber or an
expensive expansion tank and installation.

What's wrong? my observatons? Well, I don't have a PRV,
didn't even have a meter for years. Don't know if there is
check valve. With all the cautioning by the water company
about antisiphon valves and making sure you don't cross hook
up domestic and irrigation systems, I suspect the water
company doesn't believe there are any check valves either.
I didn't get out my physics books to check the volume
difference of 50 gallons of water at 60 degrees and and at
130 degrees. Somebody can do it, but I doubt that it is
much. You open a tap, you flush the stool and the system
stabilizes. When your washing machine is on, it is
constantly opening a valve, so any pressure build up
decreases. My system doesn't burp.

I like the idea of your system, but please don't set it at
80 psi for me, it woud be dribbling all the time, since my
pressure often read 80 psi.

BTW, if you have anti water hammer devices, they will
provide expansion room. But then I don't have them either.
Guess I could go just go buy a pressure release that's set
to 85 and stick it on an outside faucet, but don't think I
will.