Need help! - Low pressure in sprinkler system - The well to blame? Solutions?

Users who are viewing this thread

PJSii

New Member
Messages
5
Reaction score
0
Points
1
Location
FL
2 of 3 sprinkler zones have very low pressure. I have completely ruled out leaks and valves. The problem must be the source. At one point the system was perfectly balanced. Why would 2/3 zones have low pressure now? Something must have changed. The question is, is it the pump, pressure tank, or well? The system was not used for a little over a year. The water produced is slightly brown in color.

I have somewhat ruled out the pressure tank and pump. I inspected the tank (2.1 gallons) and re-charged it to the factory air charge of 28 PSI. The pump is a 3/4 HP jet pump rated for 10 GPM and I confirmed it pumps out 10 GPM with the 5 gallon bucket test at the faucet right off the pump numerous times consistently producing 10 GPM.

So is the well itself to blame?

Here's the part that baffles me, and I'm hoping someone knowledgeable on wells can enlighten me: Every single sprinkler head in the problematic zones have been capped off to inspect the pressure. Capped or not, the pressure at the gauge in those 2 zones behaves the same. As soon as I open the valve on one of those zones, the gauge drops to 0 and slowly builds up to 10 PSI, but no more.

Zone 3 has 3 rotating heads in the backyard. The well, pump, tank and valves are all in the backyard too. Zone 3, the working zone, maintains a constant 30 PSI, which is fine (40 would be better though...). Zone 3 does appear to be the smallest of the zones, having only 3 heads. Zone 1 has 9 spray heads, 6 on one side of the house, 3 on the other, so the piping goes all the way around the house. Zone 2 is similar in layout, with 4 rotating heads in the front yard and piping that wraps around to the front of the house. At one point all these heads worked fine with full pressure. So something changed.

So after doing lots of research online what I have come up with so far is this:
The water table may have dropped and the static head of water in the well is much less now. Zone 3 has less pipes overall so it doesn't immediately deplete the static head in the well so once it's pipes pressurize it's only the loss at the sprinkler heads that can easily keep up with the recovery rate of the well. However, zones 1 and 2, with much more piping, are emptying the static head upon pressurizing their pipes, reducing the flow of the pump from 10 GPM to the recovery rate of the well thus decreasing pressure giving me the 10 PSI reading on the gauge.

Assuming my theory is correct, I'm still baffled why capped heads don't pressurize the system. Is the pump pumping at that point just to maintain whatever little pressure it has produced? I'm confused.

If it is a lowered water table, what are some of my options to get the pressure back in my zones? Larger pressure tank? More powerful pump? Any help appreciated.
 

PJSii

New Member
Messages
5
Reaction score
0
Points
1
Location
FL
My guess is the jet nozzle in the pump is clogged.

Is this a common problem, considered regular maintenance on a jet pump? It has never been serviced.

I have a 3/4 HP Flotec FP4022-10 rated for 10 GPM and I confirmed the flow is 10 GPM with the 5-gallon bucket test numerous times. If the pump is producing the correct flow from the faucet that's right at the pump wouldn't that mean the pump is fine? If it were only producing, say, 5 GPM when it's rated for 10, then I would point blame to the pump. Or am I way off on this? Does the jet nozzle have more to do with pressure than flow? I thought the pressure tank took care of all that. Or is the pressure tank merely to ensure the proper cut-in and cut-off times? Is the pump what provides the actual running pressure? I guess I've got some more research to do on this. :confused:

Also, I just want to clarify that the system does not build it's pressure up, even with capped sprinkler heads. This happens in 2 out of 3 zones. There are absolutely no leaks. So where is the water going? Why does the pressure sit at 10 PSI in these zones and not build up to the cut-off pressure? The pump just keeps running at 10 PSI. Is the water flowing through the pump or what? It sure flows through on zone 3. It sure flows through from the immediate faucet. :confused:

Any and all help appreciated! :D
 
Last edited:

PJSii

New Member
Messages
5
Reaction score
0
Points
1
Location
FL
I took my pump apart in hopes of finding a clogged nozzle but it was clean inside. I separated the motor from the housing leaving all pipes intact and was able to fully inspect the venturi/nozzle area. I also removed a bleed screw on the housing that is behind the nozzle and it made it easy to see light shining right through the whole nozzle with no obstructions. I'm disappointed because I thought this was going to be it. So with the pump all back together and primed and working the same as it was I'm stumped again. The flow is there, the pump produces 10 GPM but it just won't build pressure in my sprinkler zones 1 and 2, even with all heads capped.

Could a dropped water table have this effect? I don't really know the physics of it all, but in my head I am thinking zone 3 is the smallest so it doesn't deplete the static water head in the well upon pressurizing the zone, thus once pressurized only what's needed to spray from the sprinkler heads is being demanded from the well. But zones 1 and 2, having much more piping and heads, are depleting the static head upon start up and thus are limited by the well's recharge rate, which could be slow in this case. But even if that were true, why when the heads are capped does the PSI gauge read 10 and not build up though? I'm losing pressure somewhere...but from where? I wish it were something as simple as a leak but it would have to be two leaks and I see zero leaks.

Any more suggestions or ideas?
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,413
Points
113
Location
IL
Here's the part that baffles me, and I'm hoping someone knowledgeable on wells can enlighten me: Every single sprinkler head in the problematic zones have been capped off to inspect the pressure. Capped or not, the pressure at the gauge in those 2 zones behaves the same. As soon as I open the valve on one of those zones, the gauge drops to 0 and slowly builds up to 10 PSI, but no more.
"The gauge" is the one back at the pump?

When you open zone 1 or zone 2, with all heads capped, you see no water come out. But "the gauge" drops to zero initially and the pressure climbs to only 10 PSI. I think the 2 big underground leak theory is the only one that sees to match the symptoms. Did you get the yard aerated? Did somebody do some roto-tilling? Did a utility install a new underground cable or pipe that passes through the two problem zones?

I would try leaving one zone pressurized for several hours with capped outlets and see if a wet spot develops.

Now if "the gauge" is not back at the pump, where is it?
 

PJSii

New Member
Messages
5
Reaction score
0
Points
1
Location
FL
"The gauge" is the one back at the pump?

When you open zone 1 or zone 2, with all heads capped, you see no water come out. But "the gauge" drops to zero initially and the pressure climbs to only 10 PSI. I think the 2 big underground leak theory is the only one that sees to match the symptoms. Did you get the yard aerated? Did somebody do some roto-tilling? Did a utility install a new underground cable or pipe that passes through the two problem zones?

I would try leaving one zone pressurized for several hours with capped outlets and see if a wet spot develops.

Now if "the gauge" is not back at the pump, where is it?

Yeah, the gauge is right at the pump.

No work like that was done in the yard but these two zones do follow each other for the most part and it's likely whatever has potentially broken one pipe happened to both at the same time/spot. I'll try letting the zone run for several hours as you suggest. I was afraid to let the pump run that long but after some research it does no harm at all (as long as the water is flowing).
 

PJSii

New Member
Messages
5
Reaction score
0
Points
1
Location
FL
I found a leak! I ran zone 1 for a few hours and it finally revealed itself! It was a spray head by the street buried deep and attached directly to the PVC with no funny pipe. I ran out of time to actually dig it all up and fix it and I still need to run zone 2 for a few hours to find it's leak. I am predicting similar results with zone 2. I appreciate all the help. I probably shouldn't have been so quick to rule out the leaks but I simply wasn't seeing them. If I had known better to let it run for hours on end....oh well, I learned A LOT about sprinkler systems. I mean, I've had valves apart and inspected, learned about pressure tanks, took a pump in HALF and inspected its insides, learned a bit about wells.....whew :p. Well, I'll follow up in a couple days and confirm that it was TWO separate leaks and that the system pressurizes. I hope so anyways. :D:p
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks