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Discussion Starter · #1 ·
Greetings!

My company primarily has done pool maintenance and install but we are expanding into landscaping installs.

I've personally designed and installed 8 irrigation systems over the last 10 years. I've always used some combination of rigid 3/4" or 1" for the main runs and swing/funny/flex for the risers. I've also used a combination of regular adjustable heads and MPRotators. They've always performed beautifully. I've never considered myself a pro, but I've always been confident I have done as good or better than some of the professional companies here in my area (after witnessing their installations at our new-construction clients homes).

This brings me to our current situation.

We have a client who requested Hunter PR40 bodies and MPRotator 800SR heads for a very narrow strip of lawn (11' x 80'). The home is modern, so this fits its style.
We installed a main 'spine' supply of 3/4 rigid down the center, and then branched off of this much like 'ribs' for each sprinkler with swing/funny pipe and a barbed elbow at each end. This was to provide mostly equal flow to each of the branches. There are 16 sprinklers on this and they are well balanced all the way down the yard in terms of flex pipe length and distance.

We turned it on to test, and with every test, we have identified a new weak point in a flex-to-barb connection. We are at 5 leaks at this point. One of the tests also totally blew up the auto-drain valve (it was a cheaper Orbit style, but they've never failed like this before). We kept blaming ourselves for over working the flex at the fitting, but after the auto-drain blew up, we grew suspicious there was something else going on.

The only difference in this install than any other that I've done, are the PR40 bodies. My understanding was, you could reduce pressure at 3 places: the main, the valve or the body. We knew we had to do this on this home to achieve the narrow width constraints and we chose the pressure reducing body because they paired well with the MP800SRs. However at this point, we are afraid stuff is going to keep blowing apart underground. My concern is that these PR40 bodies are creating back-pressure in the lines. I will admit, we have not tested the water pressure, but we are pretty certain it is 80-90psi at the anti-siphon valve. This has been the norm for our area and, again, I have never had any issues with things leaking or blowing apart when we used the unregulated ProSpray bodies. Additionally, we always designed the systems with enough volume to take advantage of the high pressure (most areas had consistent high culinary and high secondary water pressures of 80-90psi).

I am willing to accept ignorance here. For what it's worth, we have also tried reducing pressure right at the valve, by installing the Accu-Sync regulator, and all this caused was insane water-hammer/air-hammer and banging/oscillation that continued in perpetuity, and only stopped if you opened the air relief on the valve itself. No matter what the adjustments were on anything, it would not stop banging.

The sod has now been laid (we couldn't hold them off) and our temporary solution is to close the anti-siphon 95% of the way to reduce volume, and therefore indirectly reduce the pressure going into the manifold. Obviously it can't stay like this.

Short of installing a $200 pressure reducer before the manifold, is there something else to explore? Are we even on the right path as far as blaming the pressure or the PR40s?

The restriction at the anti-siphon valve is working for now, so our embarrassing solution may be to add a ball valve before the Hunter valve and restrict the volume this way if everything else fails to correct the issue.
 

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The cause is "high pressure potential"

While the heads you mentioned can reduce downstream pressures (nozzle inlet pressure), and indirectly keep upstream pressures higher by allowing reduced flow and friction loss, in certain situations...:

ultimately they are not the initiating-cause of the high pressure.
(if you would like for me to change the thread title I will be happy to.)

for the cost of the installation as described: checking static and dynamic pressures would cost pennies and is an excellent next step.
 

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Discussion Starter · #4 ·
The cause is "high pressure potential"

While the heads you mentioned can reduce downstream pressures (nozzle inlet pressure), and indirectly keep upstream pressures higher by allowing reduced flow and friction loss, in certain situations...:

ultimately they are not the initiating-cause of the high pressure.
(if you would like for me to change the thread title I will be happy to.)

for the cost of the installation as described: checking static and dynamic pressures would cost pennies and is an excellent next step.
We figured this needed to be our next test. The reason I took the time to ask, though, is because assuming we find the pressure to be as high or higher than 90psi, we'd like to know our options for taming the high pressure. I was hopeful the AccuSync would solve it, but it caused new issues. So now we're left with adding a $200 regulator. I just wanted to be sure that was really the last option.

The PR40s alone solves the pressure at the head, but it does not solve the pressure in the lines. Which, again, has never posed an issue prior and we assume this is because every other system was unregulated at the heads. I was just wondering if the logic was sound, that this was the difference. I completely understand that the PR40s do not increase the pressure. They merely highlight it.
 

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Discussion Starter · #6 ·
In the meantime, I am curious what causes the behavior we experienced when we added the AccuSync to the Hunter valve for this zone. I assumed this was the perfect solution: the lines to the manifold can handle the pressure just fine. Its the area beyond the valve that has weaknesses. But as soon as the AccuSync is installed below the solenoid, the system goes berserk at the valve.

Aren't we using this device exactly as intended? Is it the combination of the PR40s and the Accusync together? Does it have to be one or the other?
 

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Nothing else until pressure checked.

I had a customer describe an exploded toilet fill valve inlet that flooded his bathroom floor just a few days ago.

when i heard this, i handed him a hose bib guage, and enjoyed a moment of silence.

when he returned he reported 110 PSI static.
 

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In the meantime, I am curious what causes the behavior we experienced when we added the AccuSync to the Hunter valve for this zone. I assumed this was the perfect solution: the lines to the manifold can handle the pressure just fine. Its the area beyond the valve that has weaknesses. But as soon as the AccuSync is installed below the solenoid, the system goes berserk at the valve.

Aren't we using this device exactly as intended? Is it the combination of the PR40s and the Accusync together? Does it have to be one or the other?
There is some potential for a pressure-regulated valve to set up an oscillation, such as you described. This is one reason to have pressure readings in hand before you start work, so you know under what circumstances a problem is occurring.

There is an additional location where regulation might fit in - downstream of the zone valve, using a plastic pressure regulator, like those used for drip irrigation. Of course, they aren't as strong as a brass pressure reducing valve with a 300 psi inlet rating, so get your headings first, and see if one of them might be a solution.
 

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Discussion Starter · #9 ·
I threw an extra valve I had on the truck for pool filter cartridges that maxes out at 60psi. Unsurprisingly, the dial flipped all the way around to the underside of the holding pin faster than you can blink. I'm wondering if the static pressure is even higher than 90psi. I'll acquire a higher rated gauge and report back.
 

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Discussion Starter · #11 ·
I also tested the spigot on the house as a control; it read at 55psi. So it seems the gauge is accurate. I can't seem to add another photo today (1-a-day limit?).
 

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I also tested the spigot on the house as a control; it read at 55psi. So it seems the gauge is accurate. I can't seem to add another photo today (1-a-day limit?).
They want a bit more user 'experience' before photo restrictions are loosened.
At least you didn't peg the 200 psi gauge. In actual operation, you'd be preferring a 300 psi gauge on that supply, so that pressure spikes wouldn't damage the needle.
The good news is that you are at the point where a brass pressure reducing valve in the supply becomes an absolute no-brainer remedy. What's your pipe size? Water meter size?
 

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Discussion Starter · #13 ·
They want a bit more user 'experience' before photo restrictions are loosened.
At least you didn't peg the 200 psi gauge. In actual operation, you'd be preferring a 300 psi gauge on that supply, so that pressure spikes wouldn't damage the needle.
The good news is that you are at the point where a brass pressure reducing valve in the supply becomes an absolute no-brainer remedy. What's your pipe size? Water meter size?
Meter is labelled '5/8 Model'.

Pipe is 3/4 PEX shortly after the copper, which also appears to be 3/4". We mated the 3/4 PEX construction riser/spigot a 1" anti-siphon and 1" rigid to the manifold.

Our current discussion is now where to put it. We could place it right after the anti-siphon, but the client likes the idea of having that pressure available at spigots in the backyard at a future date. So we'll probably just throw a smaller brass reducer before the manifold itself. Something like the the Watts LFN45B.
 

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My company primarily has done pool maintenance and install but we are expanding into landscaping installs.
Welcome to the world of irrigation professionals....where our motto is "Never assume anything"....

Always always always know your static pressure before design and install, better yet static pressure and dynamic pressure at a variety of flow rates....
 

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Meter is labelled '5/8 Model'.

Pipe is 3/4 PEX shortly after the copper, which also appears to be 3/4". We mated the 3/4 PEX construction riser/spigot a 1" anti-siphon and 1" rigid to the manifold.

Our current discussion is now where to put it. We could place it right after the anti-siphon, but the client likes the idea of having that pressure available at spigots in the backyard at a future date. So we'll probably just throw a smaller brass reducer before the manifold itself. Something like the the Watts LFN45B.
You should let the PRV protect everything, including the hose bibs, since a hose with a trigger spray could burst with 160 psi. There are high-pressure springs made that you could retrofit a PRV with (depending on make and model), if their 75 psi top end isn't enough.
If you got PEX tubing like you see in home centers, you could cut in a PEX-ends PRV (PEX-B type shown in the photo)

 

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Discussion Starter · #16 ·
You should let the PRV protect everything, including the hose bibs, since a hose with a trigger spray could burst with 160 psi. There are high-pressure springs made that you could retrofit a PRV with (depending on make and model), if their 75 psi top end isn't enough.
If you got PEX tubing like you see in home centers, you could cut in a PEX-ends PRV (PEX-B type shown in the photo)

Thanks Boots,

We connected the PEX to the anti-siphon pretty close to the ground since the adapters add some vertical hight and we didn't want it too tall for a faux rock. We had planned on adding the PRV after the back flow preventer on the down-swing. Does the anti-siphon also need protection from this pressure?

Also, the valve you have shown above seems to permit the pressure to be adjusted up to 140; is that correct? So we could add that one to the main line, with a more adjustable range so they can have good pressure (half-acre of land still to landscape) and add yet another such as the one I referenced, right before the manifold?
 

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Discussion Starter · #17 ·
Welcome to the world of irrigation professionals....where our motto is "Never assume anything"....

Always always always know your static pressure before design and install, better yet static pressure and dynamic pressure at a variety of flow rates....
Thank you. We definitely learned that lesson this time around. We've never seen pressure this high; it's never exceeded 90psi before. To say I was shocked when it hit 155 is an obvious understatement.
 

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Yeah dont let the homeowners steer you into thinking 100+ PSI at a hose bib is smart. Its bad for the hose (left out in the sun, no doubt), its bad for the fittings, and its bad for someone getting hit by a jet at 100+ PSI.

By all means the PRV should be installed before everything else to honestly give all those fittings a break from the excessive PSI
 

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....the valve you have shown above seems to permit the pressure to be adjusted up to 140; is that correct?.....
No, that's just the range of the gauge. Most all PRVs will have a max setting of 75 psi, unless you special-order a wider pressure range model (what the hey, it's only money). I recommend trying a standard model first. 75-80 psi is more than enough for the sprinkler system, and these things will surprise you, because it won't act like a water supply with 75 psi street pressure, it will be more, what with the 150+ psi you have.
 

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Discussion Starter · #20 ·
Yeah dont let the homeowners steer you into thinking 100+ PSI at a hose bib is smart. Its bad for the hose (left out in the sun, no doubt), its bad for the fittings, and its bad for someone getting hit by a jet at 100+ PSI.

By all means the PRV should be installed before everything else to honestly give all those fittings a break from the excessive PSI
Also lesson learned. It blew two holes in the hose we were using. It was a black heavy duty hose that had been left to the sun for years, but it was pretty dramatic each time it blew apart. It also made our brand new hose pretty swollen.

We really have been shocked that this high of a pressure was even a possibility given the street location etc. How common is 155psi at the meter?
No, that's just the range of the gauge. Most all PRVs will have a max setting of 75 psi, unless you special-order a wider pressure range model (what the hey, it's only money). I recommend trying a standard model first. 75-80 psi is more than enough for the sprinkler system, and these things will surprise you, because it won't act like a water supply with 75 psi street pressure, it will be more, what with the 150+ psi you have.
Gotcha. I think they just enjoy the volume is greater than what they get off the house and they don't want to lose that. But if maxing out a PRV will still give them that 'experience' then everyone is happy.
 
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