PRV for irrigation below grade?

[Matthew Hardy]

I am replacing my sprinkler system in connection with a total redo of my landscaping. I am putting together my assembly with a reduced pressure backflow preventer. The previous setup had the backflow preventer on the assembly above ground (over 12", but lower than 36" per give), but the PRV was below grade in a circular valve box. Is there any reason I cannot add it after the backflow preventer on the assembly? Why are they buried some times? The PRV on the line to the house is above grade right before the it enters the exterior wall.

I can put the prv below grade, but would prefer above as the previous was really messy despite being in the valve box (eg rust, dirt, etc).

 

[RichMoney]

I am not familiar with a PRV, what does the acronym stand for? The PVB back-flows, must be 12" above the highest outlet. So they have to be installed above ground.

I always like to see all back-flows above ground, it makes them so much easier to service, but sometimes due to location this is not possible. No one wants a back-flow sticking up in the middle of their front yard!
Rich@sprinklerresource.com

 

[Sponsor]

 

[Matthew Hardy]

I am not familiar with a PRV, what does the acronym stand for? The PVB back-flows, must be 12" above the highest outlet. So they have to be installed above ground.

I always like to see all back-flows above ground, it makes them so much easier to service, but sometimes due to location this is not possible. No one wants a back-flow sticking up in the middle of their front yard!
Rich@sprinklerresource.com

Sorry for the acronym. I am asking about a pressure reducing valve. The water pressure from the street is really high where I live so a pressure reducing valve is necessary to lower the psi to levels that do not inflict damage to the pipes / fixtures / appliances.

I have the PRV for the house set around 55 PSI. I recently installed a water heater and had to add a thermal expansion tank to bring the install up to current code. The irrigation line has a separate PRV and I will set it around 50 psi.

I can replicate the previous install below grade, but am planning on putting the PRV in the same assembly as the backflow preventer if possible. My hesitation is that the previous install put it below grade so wondering if he or she had a reason. Could be he or she did not want to mess with the steel pipes so went below grade so they could use pvc. I am building the assembly using copper so can simply add the PRV unless it is supposed to be below grade.

 

[WorthFlorida]

Since a PRV is adjustable you want it above ground for access but it really doesn't need to be since it is a sealed unit. Do place it before the PVB. The PVB must be above ground since it works on water and atmospheric pressure. It will allow air to enter to break any siphon.

(PRV installation instructions)
http://media.wattswater.com/1910259.pdf


Typical Installation (https://www.sprinklerwarehouse.com/Wilkins-Pressure-Vacuum-Breaker-p/wk720a-075.htm)

Local codes shall govern installation requirements. Unless otherwise specified, the assembly shall be mounted at a minimum of 12" (305mm) above the highest piping or outlet downstream of the device. Install with adequate drain and sufficient side clearance for testing and maintenance. The installation shall be made so that no part of the unit can be submerged. A pressure vacuum breaker cannot be installed where back-pressure could occur or where spillage of water from vent could cause damage.

SpecificationInstallation

 

[Matthew Hardy]

Since a PRV is adjustable you want it above ground for access but it really doesn't need to be since it is a sealed unit. Do place it before the PVB. The PVB must be above ground since it works on water and atmospheric pressure. It will allow air to enter to break any siphon.

(PRV installation instructions)
http://media.wattswater.com/1910259.pdf


Typical Installation (https://www.sprinklerwarehouse.com/Wilkins-Pressure-Vacuum-Breaker-p/wk720a-075.htm)

Local codes shall govern installation requirements. Unless otherwise specified, the assembly shall be mounted at a minimum of 12" (305mm) above the highest piping or outlet downstream of the device. Install with adequate drain and sufficient side clearance for testing and maintenance. The installation shall be made so that no part of the unit can be submerged. A pressure vacuum breaker cannot be installed where back-pressure could occur or where spillage of water from vent could cause damage.

SpecificationInstallation

Thank you. For backflow, I am using a reduced pressure backflow preventer vs a pressure vacuum breaker, but understand same principles apply. It will be at about the highest point in the yard and I actually have it about 24 inches above grade just to be safe and ensure it will be at least 12"above any other outlet that might go in the future.

On the PRV, I could adjust the previous one as it was in a circular valve box, but will be much easier and cleaner to have above grade. Just sweating the copper pipes right now and about to install. Thanks for the help.