PRV Location in Run Pictured

[jepalan]

Greetings -

City made some changes and I have 98 psi from the source now.
Question 1: Does it matter if I locate a PRV just before or after the Dual Check in this picture ?

Our city adopts 2015 UPC without modification to excess-pressure sections. I assume I need to install a 3/4" x 3/4" PRV with integral strainer. I also assume a dual union PRV would be easiest ?
Question 2: Is above correct? Am I missing anything?
(Yes, I already have expansion tank at WH cold inlet.)

Thanks in advance for your time & help.

 

[hj]

I always use double unions so the device can just slide in between them. The PRV is a "backflow preventer" so the double check should be redundant.

 

[Sponsor]

 

[jepalan]

I did a little more research. City is in process of adopting 2015 UPC. 2009 UPC is currently in effect with modification. They added specific language to 602.1 as follows:

602.1 No installation of potable water supply piping or part thereof shall be made in such a manner that it will be possible for used, unclean, polluted, or contaminated water, mixtures, or substances to enter any portion of such piping from any tank, receptor, equipment, or plumbing fixture by reason of back siphonage, suction, or any other cause, either during normal use and operation thereof, or when any such tank, receptor, equipment, or plumbing fixture is flooded or subject to pressure exceeding the operating pressure in the hot or cold water piping. A dual check backflow preventer which conforms to ASSE 1024 shall be installed on the building side immediately downstream of the water meter where the water service enters the building.

Based on this I will leave the check valve in the line. Also, since it says "immediately downstream of the water meter", I wonder if I should place the PRV immediately upstream of the check? I think I'll call the inspector first.

 

[krik]

Sounds to me like the easiest change is to make sure the current dual check is ASSE 1024 conformant, and then move the sprinkler tee downstream from that dual check valve.

 

[jepalan]

The sprinkler tee runs straight up to a PVB in the false ceiling of the utility room before heading outside. Best I can tell, the PVB meets our code for backflow prevention from the sprinkler system without it being tapped downstream of the dual check. There is plenty of vertical run above the dual check to insert the PRV - I would prefer to insert it there and leave the sprinkler system on full city pressure if it passes inspection. I'll see what inspector says.

 

[krik]

But why are you focused on the PRV? the code change doesn't seem to require it. So moving the tee would still run the sprinkler full pressure, but meet the changed code of having the dual check as the first thing downstream of the meter. Maybe I'm missing something.

 

[jepalan]

Yeah, sorry - the thread went a little sideways regarding the double check.

The whole story goes like this...
1) I started getting daily spurt of water from TPR on my 2 yr old water heater. Check valve and expansion tank already installed.
2) After investigation, I found 98psi at city feed and throughout house. Call to inspector confirmed that they had made changes to supply & psi went up in neighborhood.
3) Further investigation, I found the expansion pre-charge was only 22psi. I increased it to 80 psi and TPR spurt stopped.
4) City code says no more than 80psi in the house, good practice says 50~70 even better. So I decided to add PRV to my system.
^^^ this is when I made my original post to ask about best place to install PRV.
5) HJ suggested *replacing* dual check with the PRV. My point about the additional code snippet was that I didn't want to *replace* the dual check as it is explicitly required by the city, rather I would just *add* the PRV. I'd rather leave the sprinkler tee alone *if* I can get away with it.

The whole point of the discussion is that I am adding the PRV one way or another. Gotta get house to 80 psi or lower.

BTW - I am just a homeowner that likes learning before doing. Not a plumber here.
And thanks for reading and commenting - I do appreciate it.

 

[krik]

I don't think you can leave the tee alone - the code clearly (well, actually vaguely) says the first thing after the meter has to be the double check. So you'd go meter -> check -> tee -> prv

EDIT: I would also check with the city whether over 80 PSI is OK for the sprinklers.

 

[jepalan]

Thanks Krik -
I thought I would close this out with an update. My inspector said the sprinkler Tee DOES have to be moved downstream of the dual-check. BUT, he said the sprinkler does NOT have to be downstream of the PRV - he would pass it either way. His reasoning is the interpretation of the following sentence in section 608.2 Excessive Water Pressure "...Such regulator(s) shall control the pressure to all water outlets in the building". The argument being that irrigation outlets are not "in the building". So choice is mine whether to regulate the irrigation feed or not.

 

[hj]

I would be more concerned about 90 psi to the irrigation system than I would to the house. Usually it is NOT designed for pressures like that.

 

[Themp]

The water pressure in our city is 100psi. Most people with irrigation systems pay to have a separate meter for the irrigation installed because the costs are lower for water(no sewer charge and fees). The city requires a backflow preventer after the meter that is 1 foot above grade. It has to be tested every 3 years. I do not know of anyone in my neighborhood that has a PRV to reduce this pressure for irrigation. I know when my system was inspected they did not require any PRV to be installed. I looked up the Orbit valve I use and it says it can handle 150psi. But other ones I found(Rainbird) say the max is 70psi. So, I would say that most irrigation systems in the city are going to have higher psi than it should. I would think the valves are the weakest point here as when they open and the heads are spraying I assume the psi in the pipes and heads is reduced.