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cwwest

Active Member

Posts: 9

Location: USA

1

Wednesday, February 28th 2007, 9:45am

low pressure

I have a 5 zone (lake pump) system. Has been working great for 8 years. Now zone 3 has very low pressure. Have done the following: Removed all sprinkler heads (5) and capped uprights - attached pressure gauge, turned pump on = great presure. Turned pump off and waited - pressure did not drop = no leaks! Reinstalled heads one at a time and checked pressure - one head = great pressure - as each head is reinstalled pressure drops. Replaced control valve = no difference. I am at a loss. Does not appear to have a leak and the valve is new. That is everything in a simple system. What now? Thanks for any suggestions.

drpete3

Supreme Member

Posts: 375

Location: USA

2

Wednesday, February 28th 2007, 11:03am

All other zones are fine? Zone 3 is the only one working incorrectly? This would indicate your pump is fine, as long as all of your zones are about the same. So you either have somthing wriong with your valve or a leak. your test for a leak says your good. I think you have a problem with the valve. Does it have flow control? Installed backwards? Look at the valve for your problem.

Think in these terms somthing is restricting the flow of water thru zone 3. Where/what could it be?
Thanks,

Pete

cwwest

Active Member

Posts: 9

Location: USA

3

Wednesday, February 28th 2007, 12:41pm

Thanks for the reply. This is why I am at a loss. All other zones work OK. (So not a pump problem) Zone 3 has worked great for the last 8 years (so not an installation problem) Leak test shows no leak. ( So not a leak problem) All sprinklers on the zone fail the same way ( So is a common poblem) I just replaced the control valve with no improvement. (Not a valve problem) What else is there? Mystery!

cwwest

Active Member

Posts: 9

Location: USA

4

Wednesday, February 28th 2007, 12:41pm

Thanks for the reply. This is why I am at a loss. All other zones work OK. (So not a pump problem) Zone 3 has worked great for the last 8 years (so not an installation problem) Leak test shows no leak. ( So not a leak problem) All sprinklers on the zone fail the same way ( So is a common poblem) I just replaced the control valve with no improvement. (Not a valve problem) What else is there? Mystery!

jmduke7

Advanced Member

Posts: 158

Location: FT. Walton Beach, Florida

5

Wednesday, February 28th 2007, 4:26pm

First we need to look at the pump, and how it is hooked up to draw out of the lake / pond. Is there a screen on it? Is there a check valve on it? Is zone 3 about the same size (as in GPM) as the others? Is zone 3 the same distance away from the pump as the other zones? What is the water quality in the pond / lake? Did you replace the whole valve or just the diaphragm? I deal with lake systems allot, and have found that the problem is usually something simple to fix, but hard to diagnose.
Josh
Irrigation /Landscape Lighting / Pump and Well Specialist

cwwest

Active Member

Posts: 9

Location: USA

6

Thursday, March 1st 2007, 10:41am

Thanks for the reply. Lake (LBJ in central Texas) is very good quality. All other zones works as they always did, most are the same or larger in size as 3. I replaced the entire assembly except for the body. Inspection showed no problems in the body. This system (& zone 3) has been working perfectly for 8 years. Today I capped all the sprinklers on zone 3 and took pressure readings. With all heads operational I have 10 PSI. With all capped I have 40 PSI. With 2 operational I have 25 PSI. Zone 3 has 5 large and 2 mini heads. I let zone 3 run for over 2 1/2 hours with all capped (left a small bypass to trickle water so as to not burn up the pump). Looked for wet spots and found none. I know where the pipes run as I installed the system originally. I am stumped. This is such a simple system - can't figure what could be wrong!

jmduke7

Advanced Member

Posts: 158

Location: FT. Walton Beach, Florida

7

Thursday, March 1st 2007, 12:50pm

Kinda sound as if you have a pinched line, or a valve that does not open all the way. What brand and model valve is it? Do you have any trees in the area of this zone?
Josh
Irrigation /Landscape Lighting / Pump and Well Specialist

drpete3

Supreme Member

Posts: 375

Location: USA

8

Friday, March 2nd 2007, 4:45am

Tell us why you are positive the valve is OK.
Thanks,

Pete

cwwest

Active Member

Posts: 9

Location: USA

9

Saturday, March 3rd 2007, 8:59am

Valve body is clean, no cracks, dirt, etc. All other components were replaced, seats, diaphragm, solenoid, etc. After this replacement - problem is still exactly the same. Pressure (as measured at a tap I had installed about the center of the run to the first head) is OK if the heads are capped. This is the only zone with a problem. Thanks for your interest. I am about to start digging. At a loss as to what else to do.

jmduke7

Advanced Member

Posts: 158

Location: FT. Walton Beach, Florida

10

Saturday, March 3rd 2007, 11:53am

What model and make is the valve?
Josh
Irrigation /Landscape Lighting / Pump and Well Specialist

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