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Tuesday, August 4th 2020, 3:32pm

Valve maintenance, check valves, anti-siphons and water pressure

I apologize as that is a lot for one subject line. I have been doing some maintenance on my phalanx of Irritorol 2711DPR valves. This video shows some dripping from a valve even after doing some maintenance. At first I thought it was an unfixed leak, but I think it's just backflow since it still happens even after closing the main ball valve, plus I can stop the backflow putting my finger into the downstream hole on the bottom of the anti-siphon.

One backflow weirdness though: I can run a single zone and afterward MANY of the valves seem to want to backflow drip in sympathy. I'm not sure why that would be the case? And the dripping can go on for 45 minutes.

For the maintenance, most valves I think have needed just a cleaning of the diaphragm, one diaphragm got replaced, and the gasketry on the anti-siphons has gotten to the disintegration point where I need to replace them (they leave so much black on my hands as if they are permanent markers). I think the cheapest way to get parts is just to buy new valves and cherry pick. Solenoids are all working fine, at least in that they turn zones on / off.

My valves are downhill from almost all my zones and some of the zones themselves have slopes. So I of course get low-head drainage, and I'm considering getting some on-head check valves to prevent the low-head drainage. (The affected heads are all Hunter PGP or Rain Bird 1800 so there's a way to put check valves right into the heads.) But I also wonder about putting in inline ¾" PVC check valves like thesewhere needed on the laterals right after they leave the valves. Is this advisable?

Finally, the water pressure on the spigot next to the valves is 120psi. That's on the line before it gets into the house and to a pressure control valve. I know, it's a lot. My sprinklers fog too much and this is no doubt why. Do they make a PVC-connectable pressure control valve for sprinkler systems or am I just going to need to install another whole-house PCV?

mrfixit

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Posts: 2,552

Location: USA

2

Wednesday, August 5th 2020, 1:36am

You can buy check valves for the PGP's. Just unscrew the innards of the sprinkler, take out the screen at the bottom, put in the check valve.

The RainBird 1800's they don't make a check valve that you can just install that way that I know of. You'll need to buy SAM's. Then swap out the innards. Meaning unscrew the cap and pull the guts out of the sprinkler body, leaving the body in the ground. Or you can just install the whole new head. Fairly simple to do. They only have SAM's on 4" pop ups and taller. But I taught myself a new trick the other day. I needed a 2" SAM so I pried the check out of a 4". It came right off. Was held on by four tiny glue points then I glued it onto the 2". So far so good.

As far as the pressure goes, I'd install a brass pressure regulator.

As far as installing check valves on the outlet side, it's not legal to do. Will it solve the drainage problem, yes. But your valves are already installed incorrectly being lower than the sprinklers.

To do it right, you'd have to start over with inline valves and the proper back flow device.

And you might be the first person in history to call a mess of valves a "phalanx". haha I promise to not steal that from you.

TrippKnightlydupe

Unregistered

3

Wednesday, August 5th 2020, 3:19pm

You can buy check valves for the PGP's. Just unscrew the innards of the sprinkler, take out the screen at the bottom, put in the check valve.

The RainBird 1800's they don't make a check valve that you can just install that way that I know of. You'll need to buy SAM's. Then swap out the innards. Meaning unscrew the cap and pull the guts out of the sprinkler body, leaving the body in the ground. Or you can just install the whole new head. Fairly simple to do. They only have SAM's on 4" pop ups and taller. But I taught myself a new trick the other day. I needed a 2" SAM so I pried the check out of a 4". It came right off. Was held on by four tiny glue points then I glued it onto the 2". So far so good.

As far as the pressure goes, I'd install a brass pressure regulator.

As far as installing check valves on the outlet side, it's not legal to do. Will it solve the drainage problem, yes. But your valves are already installed incorrectly being lower than the sprinklers.

To do it right, you'd have to start over with inline valves and the proper back flow device.

And you might be the first person in history to call a mess of valves a "phalanx". haha I promise to not steal that from you.


Thx. Rain Bird told me same re: can’t buy 1800 check valves a la carte so have ordered SAM bodies for the swap. Have also ordered the PGP variants.

Hunter makes inline check valves too I thought... so they must be legal somewhere somehow. This seems more geared to put in right before the head but it’s still on the outlet side... kinda sorta maybe still in the lateral itself? https://www.sprinklerwarehouse.com/amfile/file/download/file_id/5407/product_id/30557/

I didn’t design this system and the valve location is awful (front of house, no less!). I don’t know if/how/when I can do/afford the whole-manifold transplant

mrfixit

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Posts: 2,552

Location: USA

4

Wednesday, August 5th 2020, 11:20pm

I can't say that I've never done what you're asking. It's very effective at stopping massive amounts of back flow.
I wont tell anybody if you wont.
Use a spring loaded check valve. I use King brand.
The Hunter you have picture does have a spring so you're good to go with that.

Wet_Boots

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Posts: 5,369

Location: Metro NYC

5

Friday, August 7th 2020, 11:36am

RE: Valve maintenance, check valves, anti-siphons and water pressure

My valves are downhill from almost all my zones
Then your sprinkler system has no backflow protection. The question becomes why on earth do you you want that? Absent a location for this system, the only "one-size-fits-all" remedy is a reduced pressure principle backflow prevention assembly (the old self-explanatory name is better known today by the abbreviation RPZ) You have to spend some money for the RPZ, but it gains you plumbing code compliance, which is a nice thing to have when you put your house up for sale. The only above ground plumbing in the system would be the RPZ, and the zone valves can become the standard variety located in a valve box, which ends your adventures with antisyphon valves.

For anyone with downslope zone valves, the RPZ is a worthwhile, forward-looking investment.

6

Saturday, August 8th 2020, 2:30pm

Thank ya Boots. So the RPZ would go in before the manifold set-up to cover all the valves? And then I guess I’d have to replace the anti-siphon valves with plain old valves, otherwise I assume I’d still have drain out of the anti-siphon bonnets. My valves don’t owe me much at this point. And finally to state what I believe to be true: a Reduced Pressure Zone (RPZ) valve is not just for a single zone nor does it step down your system pressure, both if which I thought when I first saw the name.

Wet_Boots

Supreme Member

Posts: 5,369

Location: Metro NYC

7

Monday, August 10th 2020, 12:25pm

Exactly. The RPZ goes upstream of the rest of the system. You would eventually replace the antisyphon valves with conventional inline valves.

You are also correct that the RPZ name is not connected to system zones. It refers to the portion of the assembly where the water pressure is reduced from the supply pressure upstream of the RPZ - it is this pressure difference that creates the physical force that closes off the water outlet built into the RPZ.

A further note on water drainage from zones. A system as you describe will benefit by not having a master valve. A master valve is designed to be an extra layer of protection - a valve that will shut off water flow even if a zone valve got stuck open. The order of water flow would be supply > backflow preventer > master valve > zone valves. All this is a good idea until steep slopes enter the picture, when high elevation water drains back through a zone valve and on through another zone valve, to exit lower elevation sprinkler heads. This back drainage becomes possible when a master valve prevents the zone valves from being pressurized 24/7 (because a zone valve can never truly be 'off' unless it has supply pressure)

One further note. There is a water pressure "cost" for installing the RPZ, but the fact that your supply pressure measured 120 psi means you can afford the 10-15 psi that an RPZ will subtract. In the unfortunate event that your zones were designed in a way that maxes out your available supply, there are ways to reduce a zone's water consumption, usually by changing nozzles, so as to compensate for the backflow preventer.

This post has been edited 1 times, last edit by "Wet_Boots" (Aug 10th 2020, 1:13pm)


8

Saturday, August 29th 2020, 1:28pm

Exactly. The RPZ goes upstream of the rest of the system. You would eventually replace the antisyphon valves with conventional inline valves.

You are also correct that the RPZ name is not connected to system zones. It refers to the portion of the assembly where the water pressure is reduced from the supply pressure upstream of the RPZ - it is this pressure difference that creates the physical force that closes off the water outlet built into the RPZ.

A further note on water drainage from zones. A system as you describe will benefit by not having a master valve. A master valve is designed to be an extra layer of protection - a valve that will shut off water flow even if a zone valve got stuck open. The order of water flow would be supply > backflow preventer > master valve > zone valves. All this is a good idea until steep slopes enter the picture, when high elevation water drains back through a zone valve and on through another zone valve, to exit lower elevation sprinkler heads. This back drainage becomes possible when a master valve prevents the zone valves from being pressurized 24/7 (because a zone valve can never truly be 'off' unless it has supply pressure)

One further note. There is a water pressure "cost" for installing the RPZ, but the fact that your supply pressure measured 120 psi means you can afford the 10-15 psi that an RPZ will subtract. In the unfortunate event that your zones were designed in a way that maxes out your available supply, there are ways to reduce a zone's water consumption, usually by changing nozzles, so as to compensate for the backflow preventer.


Is there something specific to the RPZ vs other backflow valve designs that caused you to suggest only it? My wild guess: only the RPZ can hold back the static gravitational backpressure from the water in the upslope laterals (without discharge) when nothing is running?

Wet_Boots

Supreme Member

Posts: 5,369

Location: Metro NYC

9

Saturday, August 29th 2020, 3:34pm

the RPZ is elevation-proof, and can be downhill of the sprinkler system, unlike antisyphon valves - it is also rated to protect against toxic backflow, which is the going highest standard of backflow protection, and why I give it as the one choice that makes other factors irrelevant

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