Low pressure irrigation, just 2 of 6 zones

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  #1  
Old 05-25-13, 08:36 AM
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Wink Low pressure irrigation, just 2 of 6 zones

Hi all -

First time posting on a forum like this... frustrated and very much a novice, at wits end. Kindly forgive what may ultimately be a dumb question with an obvious answer, and also forgive that it is so long... I tried to include the relevant info that might lead a brighter mind to a solution.

I have a 6 zone sprinkler system on a well in FL. It was originally 4 zones, expanded to 6 about three years ago with no problems. Driven by a 6-zone timer that is relatively new. Pump is 40 feet down, plenty of water.

A few months ago, the dear wife decided she wanted a garden, and being the dutiful husband I am, I rerouted one of the two newer zones to the first part of the garden area. A few weeks later, I rerouted the sixth zone to the expanded garden area, and ever since I did that, both zones 5 and 6 have been sketchy and intermittent. Initially, the 6th zone didn't have enough heads to support the flow and the pump was cycling (even though it was the same number of heads as zone 5 and traveling roughly the same distance over the same grade, which is about 5 feet downhill from the valves). I added another head, the cycling slowed a bit, and then added a gear head (I know... not supposed to mix them) and the cycling stopped. However, now more often than not, but interestingly not every time, those zones will run at very low pressure and just bubble. When it first started my thought was ok, shouldn't have added the gear-driven head and I cap it off to see what happens. I remove the head to cap it while the system is running, expecting to get wet while I install the cap, and it still dribbles out even without the head. Capping it off has no discernible effect on the remaining heads. However, at other times, doing this same thing (removing this head while running) leads to a 6 foot fountain as I would have expected.

Also to note is that for the sixth zone, I set up a junction farther out in the yard with manual valves so I could (theoretically at least) still occasionally water the areas previously served by that same zone before I rerouted it. The 6th zone now feeds the new area that is failing unless I close that zone manually and open another at the junction, though none of them work at full pressure. The other manual valves out there are not leaking, and note that the problem is not only with this zone but also with another which does not have this manual junction.

To simplify several weeks of trying this and that, here is what I know:

*plenty of water in the well
*pump works every time
*indoor timer works
*there are no broken lines or heads that could lead to loss of pressure
*flow controls on valves are wide open, and the valves were just replaced as part of the troubleshooting.

Two other things that may be useful to know:

*when I run through the full six zone cycle, the two zones in question will often run just fine, at full pressure. When I run them on a partial cycle with just those two zones, either by setting the timer or by manually opening each valve in turn, they will only bubble. Unfortunately, we have watering restrictions and I only want to water the newly planted areas daily, not all six zones.

*on two occasions, pressure to ALL ZONES was compromised, but generally the original four zones run perfectly. The fact that it has occurred in all zones a couple of times is the one thing that just makes no sense to me and seems to rule out obstructions/breaks in the two new zones. The original four zones are designed poorly with mix of head types but have always run well.

To the very limited portion of my brain dedicated to sprinkler knowledge, it would seem that something is up with the pressure switch. If so, I don't know where to find it, if it's the culprit so perhaps someone can give me an idea where to look... hopefully it's not at the bottom of the well. Last thing, and this may be important, is that around the time that I set up these zones, I did break both the lines accidentally with a backhoe... I took care to repair a long section of both lines, well beyond the break in both directions so there should be nothing in the lines, but perhaps that has something to do with it too.

Any help anyone can offer would be very much appreciated!
 
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  #2  
Old 05-25-13, 09:00 AM
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Welcome to the forums.

The pressure switch should be fairly near the pump. It will not be underground. It's a small square gray box attached to your water line from the pump. If you can see the pump....follow the power wiring....it will be inline with it.

Do you have a pressure gauge on the system ?
 
  #3  
Old 05-26-13, 04:21 AM
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Try plugging a couple emitters on your problem zones and see if that helps your problem.

1. I think your problem may be that you are maxing out your pump. It sounds like you are adding emitters to stop the pump from cycling on & off which means they are drawing as much water as the pump can produce which is a difficult balancing act. When the emitters can flow more water than the pump can produce then the pressure drops.

2. Pop up emitters need a good volume of water to raise the heads and generally need more flow to raise them than when in the up position. If not given good enough flow initially they will not raise and when not raised the pop up tube does not seal which gushes water making the problem worse.
 
  #4  
Old 05-26-13, 10:44 AM
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Thank you very much for the replies! First, I found what I suppose must be the pressure control switch behind the overflow tank... small tan Square D box labeled "Pumptrol" with four terminals, two black wires and two white. Haven't touched it yet.

Regarding plugging emitters, it seems the more I plug, the faster the pump cycles, presumably from pump delivering more water than heads can accommodate but perhaps there is something else afoot. I will play around with them some more today. Also note that the area previously served well on this zone (before I rerouted it) will no longer run with enough pressure to even pop up those heads when I manually configure the valves to route the water there. I would think there's a possibility of a leak in one of those manual valves on that zone, but the problem also persists in another zone with no such manual configuration.

Might be instructive to tell you what I watched today. Station turned on, immediately had what appeared to be decent pressure in that all the heads popped up and began spraying with no problem, but the patterns were very limited, only about 4-5 feet for each rather than the 10 feet expected. Sprays that way for about ten seconds, and the pump cycles off and then back on. This repeated ten times for a total of 90 seconds or so, and then all heads begin to only bubble and the pump stayed on constant from there. There are 13 heads on the zone, roughly equal to the four properly running zones. I guess my question is if there are too many heads in the zone leading to the small spray pattern, why would the pump be cycling? If there are too few heads in the zone to flow all the water the pump is trying to deliver (such that it is cycling), why aren't the heads delivering the full ten foot spray pattern before the pump cycles?

I regret I can't tell you the hp, brand, or specs of the pump down there... that would probably be helpful to know. I'll see if I can dig up an old receipt.

Again, thanks to all for your patience and advice.
 

Last edited by hometeamfla; 05-26-13 at 10:59 AM.
  #5  
Old 05-26-13, 11:20 AM
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Capped some heads...

Ok, correction on the heads on the zone... there are 14 total including the gear drive I had thrown on there. I capped that and four more, and there is no change. After a few pump power cycles (maybe 30 seconds) the heads just bubble.
 
  #6  
Old 05-27-13, 06:26 PM
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Nuclear Option

Hi all -
I did the nuclear option today and wiped out the valves on those two zones, installing manual ball valves in their place and both work fine now. Hard to believe two brand new valves were both defective, though possible I suppose.
 
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