Landscaping - sprinkler pressure low

I have 7 zones in my backyard. All of them have been working reasonably well for some time. I'm only using 2 of them (the farthest two from the main water line) as I've been bringing back my yard slowly (we bought the house 8 months ago). Recently, 6 of the seven zones lost considerable pressure (the heads just bubble).

The zone closest to the main water line seems to work fine but every zone after it has lost pressure. I can't believe the pipe is clogged in between these two valves (it's only a few inches) and I'm having trouble just evaluating what could be wrong. I can't believe there's something out in the yard broken in all 6 zones and keep coming back to what could have happened in the valves.

Does this make any sense? Can anyone shed some light on at least possible symptoms? I've been struggling with this for a week or so and the lawn I have brought back is going brown fast.

Thanks:wall:

just because two valves are close together does not mean they run areas that are nearby. It would make sense that they did, but its just not always true.

if 2 of your 7 run just fine then an obstruction sounds reasonable. Either the pipe is being squeezed or pinched off somewhere, or there is something inside of the pipe.

Do you have a pump with this system, city water, etc? Can you tell me about your water supply?

there are 7 valves all lined up next to one another. The water is city water coming in directly (I think) from the street. When I manually turn on the first valve in the line (which I was assuming was closest to the main water line), it's sprinklers come on just fine. However, when I manually turn on the next valve and every one after it, I get weak pressure and just bubbling sprinklers.

Could there be air in the line creating the blockage in between the first and second valves?

Okay. Your descriptions helped. I think one of two things is happening given the information at hand.

1. each of your remaining zones has a broken head on it.

2. Your valves have flow controls. You have them turned down.


Can you take a picture of these valves, especially any handles on top? This would help me to explain how to fix this problem for you.

I'll try and get you a picture of the actual setup tomorrow (it's too dark out right now). Here's what the valves look like (CLICK_HERE (http://images.google.com/imgres?imgurl=http://images.hardwareandtools.com/P/2364677.jpg&imgrefurl=http://www.doityourself.com/invt/2364677&usg=__Qq3y9S0uLItaiVTUNeAskpzGUOc=&h=200&w=200&sz=5&hl=en&start=107&um=1&tbnid=9LyzS4iK7zkhRM:&tbnh=104&tbnw=104&prev=/images%3Fq%3Dsprinkler%2Bvalve%26ndsp%3D20%26hl%3Den%26sa%3DN%26start%3D100%26um%3D1)

regardless, the flow control knob on top is wide open. I definitely checked this (closed and opened it) when I had them running manually.

It's difficult to believe a head is broken on every zone as 5 of the 7 zones aren't used and worked fine last time I turned them on. I don't want to believe this explaination (even if it may be the simpilest answer)

Could the grade of my yard have something to do with it? There are several sprinklers that run ~20 feet downhill from these valves. Again, I keep coming back to something like an air pocket in between the two valves.

Thanks so much for following up. I'll definitely re-check the heads in at least one zone next just to rule out this possibility.

A flow control problem is the best solution at the moment for your problem. A picture of the entire setup would help. If your valves are exactly like the one pictured then the flow control is the knob shaped like an "X". There are other valves that are similar to this that control the flow in a different manner.

Don't worry, we can solve this problem.

here are the pictures of the valves in their current state.
ImageShack Gallery (http://img200.imageshack.us/gal.php?g=img7947.jpg)

I went back through 2 of my zones and am pretty confident there aren't any broken heads or leaky pipes.

I'm hoping the pics help you see the situation.

program the clock for one zone at a time. You only have enough pressure for one zone at a time. Try each zone one at a time and see what happens.

program the clock? I've been just manually turning on one zone at a time and the pressure is too low.

I doubt there is something blocking the pipe that supplies the last 4 valves. Its possible, but why would it suddenly show up now--unless its galvanized steel down there. In that case, rust buildup could cause this.

Its more likely that your valves with low pressure are not opening all of the way for one reason or another.


When you open these manually, what part are you touching in order to do this? There is the bleeder screw, the flow control and the solenoid. I think that either your valves have gone bad or you may be operating this incorrectly.

http://img239.imageshack.us/img239/259/controls.th.jpg (http://img239.imageshack.us/i/controls.jpg/)

Here is one of your images edited pointing out which part is which.

I want to you open the flow control all the way on one of the ones that does no work well for you. Then, unscrew your solenoid all the way. Water will spray out the hole so dont stick your head right on top of it. See if this fixes your problem. If not, your valve is no longer any good.

Another possibility is that the outgoing water for the valves is being pinched off by roots or something else. Hitting 4 at once would be highly unlikely but not impossible I suppose.

I should also point out that virtually every building code around does not count these valves as legal for backflow prevention. Where you live may be an exception but better to check before you face possible fines and water shutoff.

thanks again for sticking with me on this.

1) I unscrewed the flow control as far as it goes (all the way up) for maximum flow.
2) I have been unscrewing the bleeder but in this case i unscrewed the solenoid all the way off.
Result: Water will shoot out of the solenoid hole a good 36 inches straight up. I stuck my finger over the hole to help with pressure as the sprinklers turned on. Unfortunately, still very low pressure in the sprinklers.

Thinking the whole valve may be bad, I unscrewed the part that contains the bleeder, solenoid and flow control and screwed on a brand new version. Additionally, I put on a new backflow valve on the other half.

With the new setup, I repeated steps 1 and 2 with unfortunately, the same result. I can't believe all those valves went bad at once although I continue to be willing to try anything.

My next step is to dig up the section of dirt around it. I wonder if something got in the way of the first and second valves down below (pipe broke perhaps).

Let me know what you think.

If the pipes were broken below (where your valves are) it should be extremely obvious. I mean, water would be everywhere.

Sometimes on those valves they can stop opening all of the way. However, they are so close together, replacing one would be a difficult and time consuming.

Since the feed side is all PVC it would not be compressed in some manner. If the outgoing side is poly pipe (black) then its possible they are all being pinched off by roots or something like that. But to happen to 5-6 of them all at once just seems unlikely.

I would suggest you carefully dig below the valves and see what you can find out down there. If you see galvanized pipe/nipples it could be that it is so rusted on the inside that its causing the flow of water to be bad.


Do you use a booster pump with this system or does it just run off the city water or the house water supply?

This is almost starting to sound like there is something down below inside your mainline feeding the rest of the system. How something would suddenly get in there is a mystery but to have 6 or 7 zones all go bad at the same time just seems so unlikely to rule out much else.

I hate to say it but you may have to dig down there to see what is going on. Since it is PVC you may have to cut it open and I don't think there is room to glue a joint in there so if you do anything this will end up being a huge project and it may or may not fix the problem. Try this:

Unscrew the second valve (from the water source). Use a hand-held screwdriver and not a drill. The screws are kinda cheap and they may strip if you use a power drill. Once you have it all opened, turn the water on and see if you can "flush" out any sort of rock or debris that may be caught between the first valve and the rest. If nothing comes out, try using a wire coat hanger or something similar to kinda fish out or see if you can move something that might be inside the pipes.

This will allow you to check the inside of the pipe without cutting into it which could be a major deal. I cannot 100% remember if you can do this check with these types of valves. More common valves do not allow you to do this but I think these have an open port on the bottom where they screw into the PVC fitting. I am not positive so I hope I dont make you waste a bunch of time trying this out.

At least we're in synch. This is very much the route I was going. (no, I don't use a booster pump. great question though)

I dug down from the main valve and found a T connection. One route goes into the sprinklers and the other feeds a hose spigot on the other side of the yard. The spigot pressure is just fine so I'm thinking the problem can't be in the mainline anywhere.

It's white 3/4" pvc pipe all the way down and around.

I removed the top of the first valve and turned on the water to watch it come through. everything looked good. It just bubbled up a ways. I did the same with the second and last valves (replacing the top of the last valve) and the water ran just fine as well. I wonder if I could measure the pressure in some way to determine if it's the same accross valves?

I wonder if one of the valves is stuck open reducing the pressure in the rest of the line? (this can't be because I don't hear any water running and when I turn the mainline back on, there's not a big rush to fill a void that leaked open)

reduction in pressure... reduction in pressure... I'm still thinking.

Will let you know what my next steps are.

thanks again for all your input in helping to work through this.

if there is no booster pump involved then the pressure would be the same for each specific zone. If you have nothing clogging your supply and you said you have no leaks I can only think of a few things.

1. Your other 6 zones may be trying to use more water than the system can provide. Say a few heads were replaced with ones that call for more water. If you can only supply 15 gallons per minute and the zone is trying to use 20, it will look terrible.

2. 6 out of 7 valves have gone bad. Possible, but not likely all at once.

3. 6 of 7 zones are being pinched off somewhere. Again, not very likely.



I suggest trying this:

Close the flow control on every valve except one. Open one valve at a time and see if it runs better. If so, one of your other valves is leaking and causing the drop in pressure. If not, then we can void out a leaking valve.

Try counting the heads or gallons per minute that each zone is using--maybe there is a pattern here. Your first zone may be smaller than the rest.

Any update? I'm experiencing a similar problem and am running out of ideas..

The setup he has is basically an inexpensive and bad setup. The valves are fraught with problems and prone to this kind of situation. Since they were put together so close together you cannot really do any kind of work on it without taking apart the entire thing. Not to mention these valves do not count as a vacuum breaker in almost every county.

We can help you out, delfindle, but a picture is a good place to start. Make a new thread please, because each situation is different.

I believe I now have a solution.

1) It turns out, your water pressure can change during the year and the water company isn't going to necessarily tell you (I'm on city water). They'll confirm it if you call them but it's not like they send you a notice.

2) Combine that with my system. I'm located on top of a hill, in a desert climate with a number of sprinkler zones that have a maximum of 5-6 heads on them.

3) Sprinklers have a very "Binary" aspect about them in that they either turn on all the way or they don't. It doesn't take much of a change in pressure to affect this if you're on top of a hill with sensitive water pressure, in late summer when everyone's using a lot of water, with a system that has a number of zones maxed out with heads.

Solution:
I capped two heads to increase pressure in the others. I adjusted the other heads to ensure the whole lawn still gets coverage.

Going forward, I'm replacing all of my heads with adjustable heads (turn on, off) so that I can tweak the system easily when I want to.

Thanks all for following up with this.

Capmaster Lets check for leaks real easy things you need 1 - 0 to 60 psi gage with a hose fitting (ie ) whats your house pressure ???? 2 - 6 " nipple 3 - tee 4 - (2) drain vales 5 - pluges for all your heads on that line First thig you do is recourd the water pressure in the house this can be done by screwing it in to a hose line drain next remove all sprinkler heads and cap them off all but one the last one use the nipple ,tee ,and drain vales with the gage on one vale open drain vale now open zone vale when water runs out of drain vale at end of run close vale record pressure should be about the same as house pressure next close zone vale pressure should remain the same drop very little if any after ten mins pressure should be the same if press dropes to o you have a leak
ps. water will not show all the time
ASM660