Location and Mounting/Support of pressure regulator

[thenextdon13]

Hello-
At some point in history, the local municipality changed it's water sourcing and now my water pressure is quite high (80-90PSI, I believe).

This seems to wreak havoc on my toilet and sprinkler valves, and to my understanding is quite a bit higher than it should be by code.

The main coming into the house is copper, I believe 3/4 inch. It enters through the wall at ~3' 6", then bends to vertical and joins a 'plenum' line at the ceiling level.

I'm going to add a pressure regulator in the main line, but have been trying to decide/figure out
- where to mount it (underground/box by main valve at street / in basement where main enters house
- How to support it, if in the basement (if it needs support.. is the copper itself strong enough to support the weight?)


I can update with pictures a bit later if folks feel it would be helpful..

Any input appreciated.
many thanks!

 

[Reach4]

After the pipe enters the house usually, t after the whole house shutoff valve..

 

[Sponsor]

 

[Gary Swart]

The PRV is inserted into to main supply line. It is supported by the pipe on both sides, so it needs no additional support. Do you realize you need to install an expansion tanks when you install the PRV? This does need support. Directions for this come with the tank and will depend on where the tank is placed.

 

[thenextdon13]

Thank you for your responses!
I did not realize an expansion tank was required. I'll have to do more reading-

Many thanks!

 

[Valveman]

You don't need an expansion tank if the PRV is equipped with a thermal bypass. Many are equipped that way.

 

[thenextdon13]

Looks like Oregon specialty code requires the tank, unless
'
designed by registered engineers shall be permitted to use
approved pressure relief valves in lieu of expansion tanks pro-
vided such relief valves have a maximum pressure relief set-
ting of 100 psi (689 kPa) or less'





Full text of section.
"
608.2 Excessive Water Pressure. Where static water
pressure in the water supply piping is exceeding 80 psi (552
kPa), an approved-type pressure regulator preceded by an
adequate strainer shall be installed and the static pressure
reduced to 80 psi (552 kPa) or less. Such regulator(s) shall
control the pressure to water outlets in the building unless
otherwise approved by the building official. Each such regu-
lator and strainer shall be accessibly located aboveground or
in a vault equipped with adequate means to provide drainage
and shall be protected from freezing, and shall have the
strainer readily accessible for cleaning without removing the
regulator or strainer body or disconnecting the supply piping.
Pipe size determinations shall be based on 80 percent of the
reduced pressure where using Table 6-6. An approved expan-
sion tank shall be installed in the cold water distribution pip-
ing downstream of each such regulator to prevent excessive
pressure from developing due to thermal expansion and to
maintain the pressure setting of the regulator. Expansion tanks
shall be properly sized and installed in accordance with the
manufacturer’s installation instructions and listing. Systems
designed by registered engineers shall be permitted to use
approved pressure relief valves in lieu of expansion tanks pro-
vided such relief valves have a maximum pressure relief set-
ting of 100 psi (689 kPa) or less.

 

[Valveman]

Looks like an engineer wrote that spec because it doesn't make any sense. A PRV with a thermal bypass has no pressure setting like a pressure relief valve. A thermal bypass will open to allow flow to reverse anytime the outlet pressure exceeds the inlet pressure.

But if the inlet pressure is way too high, an expansion tank would maintain the outlet pressure at or just above the outlet pressure of the PRV.

 

[Gary Swart]

Easy to tell if a PRV has the bypass feature. Install it without an expansion tank then drain enough hot water from the tank to start the tank to heat. Watch the T/P outlet. If there is no water released, you're good to go. If the T/P opens, you need the expansion tank. Water expands when heated, it has to go somewhere, it doesn't compress. It will find somewhere to go. Sorry I forgot that some new PRV have a bypass. Older ones did not.

 

[Jadnashua]

If find it really strange that people go to the trouble to put in a PRV to keep the pressure stable and not too high, then feel that a thermal bypass is sufficient. With the bypass, the house's internal pressure will constantly cycle up to the supply pressure every time the WH runs. If you want your pressure to stay stable and not rise with heating your water, add an expansion tank. WHere I live, it's code...a prv with a thermal bypass won't cut it. Yes, they do not last forever, but they're easy and inexpensive to replace when they do fail.

 

[Jadnashua]

If find it really strange that people go to the trouble to put in a PRV to keep the pressure stable and not too high, then feel that a thermal bypass is sufficient. With the bypass, the house's internal pressure will constantly cycle up to the supply pressure every time the WH runs. If you want your pressure to stay stable and not rise with heating your water, add an expansion tank. WHere I live, it's code...a prv with a thermal bypass won't cut it. Yes, they do not last forever, but they're easy and inexpensive to replace when they do fail.

 

[Valveman]

If find it really strange that people go to the trouble to put in a PRV to keep the pressure stable and not too high, then feel that a thermal bypass is sufficient. With the bypass, the house's internal pressure will constantly cycle up to the supply pressure every time the WH runs. If you want your pressure to stay stable and not rise with heating your water, add an expansion tank. WHere I live, it's code...a prv with a thermal bypass won't cut it. Yes, they do not last forever, but they're easy and inexpensive to replace when they do fail.

I completely agree with you. However, if the incoming pressure is not too high a thermal bypass will work OK. It is usually not too bad to cycle up to the supply pressure. But if the incoming pressure is really high, or if you have a check valve on the incoming line, an expansion tank is mandatory. Maybe both a thermal bypass and an expansion tank would be best. Because without an expansion tank and/or a thermal bypass, the expansion from the water heater can cause extremely high pressures.

 

[Reach4]

If anybody is wondering, the PRVs under discussion are "thermal expansion bypass" PRVs. They do not have a temperature sensor. The word "bypass" in a PRV description search will turn up PRVs with this feature.

It seems to me that having a PRV with a bypass should be acceptable in place where no checkvalve was required. It does sound like a real advantage in reducing maintenance, since expansion tanks can fail.