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Saturday, September 19th 2015, 7:40pm

Sprinkler problems 1. low pressure in all zones 2. pressure vacuum breaker leaking

Just bought a new house -- very cash poor! The day we moved in we found one of the five sprinkler zones running nonstop. I turned it off via main shutoff valve the next day, but not before wasting >20,000 gallons of water!!

I played around and localized it to one of the valves (Irritrol 205 I believe). I opened it up and checked diaphragm, which looked a little firm, though nothing obvious. No obvious debris sitting in the pipe. I switched out the diaphragm with an adjacent zone's diaphragm, and then the zone with the transplanted bad diaphragm also began to leak slightly from the valve itself and some from a couple of the sprinkler heads, even when they were turned off by the control box. I thought I had figured out the problem, and proudly ordered a replacement diaphragm online. Whenever I turned off the water, I did so in the basement adjacent to the main water valve.

While it was shipping, I tried to cycle my zones manually a few times so that my lawn didn't die. In between, I left the shutoff valve off so that I wouldn't continue to leak. Initially it was working beautifully and did it once through all zones without any problems. Great pressure, etc. I tried again a few days later, and that's when the new problem began.

When activating ANY zone, just heard a lot of hammering and then lots of water gushing out of the pressure vacuum breaker. There was little-to-no pressure at any sprinkler heads. Frustrated, I called the service company and they fiddled around with the pressure vacuum breaker (opened it, cleaned it) and then told me I should upgrade all five zones to new valves ($700+!). That's it.

Meanwhile, the new diaphragms came today. I switched out the rubber on the faulty diaphragm, and it seemed initially good because I could hear that there was no longer any leaking water when I turned the water back on. BUT when I try to cycle the zones, the water pressure is VERY low in all sprinkler heads (for both heads that are above and below the level of the valve) in all zones. Though there was no significant hammering, I opened a few bleeder valves to see if any air needed to escape or something. I doubt that did anything, but perhaps after 10 minutes of running one zone, the pressure did seem greater (though still far short of what it should be). Towards the end, there was one zone that, when activated, leaked a lot from the pressure vacuum breaker, though the other four didn't. The one that caused the leaking from the pressure vacuum breaker was one that I never played around with/opened.

I should mention that the flow control valves are all open. I did play with them on the two valves I messed around with, so I'd half understand if it was just those two zones that were messed up. (I believe they are both turned all the way clockwise so they're sticking out as much as possible.) But they're all messed up.

Any ideas?? It seems like it has to be something at the point of the valve or more proximal going back towards the main pipe because they're all uniformly affected. Problem with Pressure Vacuum Breaker? Possibly hidden debris/rocks? I haven't flushed out the pipes by opening the valve and turning on the water -- this seems like there'd be a TON of water drowning me, though if I should do it I will. What's the best way to try to flush out any debris safely in this situation? Do I have to open all the valves? The valves are semi-underground anyway so doing so would likely flood them quickly.

Thanks for any help!



Posts: 2,319

Location: USA


Sunday, September 20th 2015, 1:56am

I'd make sure the shut off valves are all the way open. You had plenty of pressure before you shut them off.
One time on an 1 1/2" PVB the system had low pressure. It turned out that both ball valves were broken. One on either side of the PVB.
Even though the handles were indicating they were on all the way the balls inside were only partially open.
That's a rare case though. Ball valves don't usually do that.
I had to cut the PVB out to see the broken ball valves. Maybe there's unions on yours.

If you have gate valves they can break in the off position. I've seen that many times. Especially on OLD valves.

Did you turn the water off at the street or anywhere else? Make sure the valve is on all the way.

Another thing I look for if there's low pressure in the whole system is a broken pressure regulator. Most systems don't have one but some do.

A broken main line would cause low pressure but I'm thinking you would have figured that one out by now if that was the case.


Active Member

Posts: 42

Location: east coast


Sunday, September 20th 2015, 11:06am

Ditto what Mr fixit said. If your backflow device is not seating and continually flushing water there is not enough pressure to seat it. Begin with checking your water source inside. A broken pipe outside beyond the valves will do the same thing but that does not appear to be the case from what you have said.




Sunday, September 20th 2015, 4:21pm

Thanks mrfixit and pass1. The rest of my house has normal water pressure, so I don't think it's a problem on the street. I haven't done anything out there. The sprinkler pipe in my basement where it takes off from the main and goes outside looks okay. I doubt it's a problem/break in that pipe because (since I replaced the diaphragm) I can now leave the sprinkler main valve open (it's a quarter turn ball valve) and there is no flow or leakage. I have verified this by watching my water meter stay steady whereas before fixing the diaphragm it would keep running. If there was a break proximal to the PVB, wouldn't it leak automatically with the valve open?

Plus it seems weird that something else would break down within two weeks of a diaphragm going kaput.

I suppose I cannot rule out the ball valves on both sides of the PVB being broken (I am sure the handles are at least open all the way), though again it'd be odd for something this rare to happen alongside a diaphragm breaking down. I'd rather not have to mess with these guys if I don't have to because that'd up the level of complexity quite a bit, it seems.

I'm not sure about a broken pressure regulator. It is a 60 year old house (sprinklers are newer though unsure age). Could I have a broken pressure regulator with the rest of my house water pressure being normal? How would I find this?

Guess there's no unifying theory that ties the two problems together. Darn!



Posts: 2,319

Location: USA


Sunday, September 20th 2015, 5:17pm

Are there any hose bibs in the yard that are connected to the same main line that the valves are connected to? Older homes usually have them. Turn one on and see how the pressure is.

You could take the bonnet off of a valve and turn the water back on to see if you have flow. It might make a watery mess but it would help diagnose.

I'm thinking on a long shot that you don't have 205 valves that you really have 2500 valves and you've installed diaphragms for the 2711DPR anti syphon valves. The diaphragms look similar but one will not work in the other. Sometimes the guys working the counter at whatever store you're shopping at will grab the wrong diaphragms. But I'm thinking they'd still work with the bleeder screw if you've done this.

Did you line up the new diaphragms correctly?

How about a picture of the valves?

As far as having two things go bad at the same time isn't as rare as you might think. It happens all the time.

This post has been edited 1 times, last edit by "mrfixit" (Sep 20th 2015, 5:22pm)




Monday, September 21st 2015, 7:41am

You may have a point about the model of Irritol valve. The serviceman told me I had a 205, but they do look similar when I just looked up the 2500. Will try go get a picture to upload. I am usually at work when the sun is up, so don't know when I'll get to it but will try by tomorrow.

I purchased the diaphragm from sprinklerworks. The plastic casing was very similar though noted different so i actually took it apart and took out the rubber diaphragm and put the new rubber diaphragm (sans the plastic) into the old diaphragm casing (which looks fine to me). The diameter and shape of the new rubber looks almost the same (including the little rubber tab) but the pattern of texture is a little different.

Maybe you're onto something. I'm not an expert and doubt that still one/two messed up diaphragms would mess up an entire system (please tell me I'm wrong!), but I'll also admit that when I bled the one/two valves that I messed with to make sure there was no air etc, I closed the bleeder screw back down when i physically left to go check the sprinkler (and instead turned the zones on via the control box).

Could the problem be that every time I have tested a zone and gone to see if it was working I used the control box? I didn't think the control box could cause this sort of problem across all zones.




Monday, September 21st 2015, 7:49am

*Note: I should mention the diaphragm I bought from SprinklerWorks

Also I've got some pictures I took previously of the diaphragm in position but I'm ashamed to say I don't know how to upload them. When i click the picture icon, it asks for a URL.


Supreme Member

Posts: 5,292

Location: Metro NYC


Monday, September 21st 2015, 9:35am

take your photos to and copy and paste the Forum Code it provides - you may get a brief ad in the anti-robot confirmation popup, but otherwise, no strings attached



Posts: 2,319

Location: USA


Tuesday, September 22nd 2015, 3:00am

If you're taking diaphragms apart and swapping parts you don't have 2500 valves. It sounds like you do have the 205's.
The brand new diaphragms would have worked just fine.
Try putting the new one back together on one of the valves and see what happens.
The 205 can be a tad tricky to rebuild. The bonnet can easily be turned a bit. The valve will not function if you've done this.
I doubt you messed up all the valves but who knows.




Tuesday, September 22nd 2015, 7:51am

let's try this old picture: (thanks for the tiny pic recommendation)

Sorry can't take any more quite yet. It's behind a bunch of shrubs in a very muddy area which is a bit of a pain to access. Will try to take more and replace with the entire new diaphragm, but realistically won't get to it for another couple of days maybe Friday.

The old and new valve both had components that unscrewed letting me switch out the rubber. The undersurface was slightly different (the part with the nut) which is why I did this.

Here's a link for the SW site I bought the new diaphragm for:

To be continued...

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