Flow Control on Well Head

[npalen]

I have been using a 1/2HP submersible in this well since 1976 to irrigate our 1/2 acre of fescue and it has never failed to deliver at least ten GPM. We've had a couple years of drouth in NCKS and the well responds saying I can deliver the ten gallons but absolutely no more and the pump will start sucking air. The underground sprinkler system has six zones with four or five heads per zone so I've had to install 2.0 GPM nozzles and keep the pressure at no more than 40 PSI as a result.

The problem comes with the method of controlling the flow and I've been trying to do it with the 1" ball valve shown in the pic. A 1/2" ball valve would probably work better but I'm wondering if someone could recommend a better way of controlling the pressure and flow. The problem with the large 1" valve trying to control the 10 GPM is that it is just not precise enough and not enough pressure will let several of the six solenoid diaphragm valves to stay partially open resulting in some water exiting heads on several zones at once.

I'm guessing that there is a low cost pressure control valve that could be plumbed into the PVC plumbing shown and would be precise enough to maintain the 10 GPM in varying conditions such as night time as well as full sun daytime?

Edit: The black object is a canister type sand filter.

 

[steve tym]

Simple, use a gate valve. Much easier to control.
More costly, use a pressure regulator such as a watts U5B.
Or, change nozzles so every zone uses the same amount of water.

 

[WranglerX]

How are your zones controlled and how are they scheduled....And is there well recovery time between watering zones....

 

[npalen]

Simple, use a gate valve. Much easier to control.
More costly, use a pressure regulator such as a watts U5B.
Or, change nozzles so every zone uses the same amount of water.

I've tried using 1/2" gate valves over the years at each sprinkler head to control flow and found they have enough slack in them to sometimes not allow any flow the next time using after adjusting them down to, say, 2.0GPM. Ball valves actually work better as they don't have any slack like a gate valve.

I have changed nozzles in every zone in an attempt to maintain the 10GPM zone flow.

Forgot to mention that each of the six Hunter solenoid valves has an onboard flow control that can adjust the diaphragm opening but they aren't really precise enough either.

I wish it was simple.

 

[npalen]

How are your zones controlled and what are your sprinkler heads.....

Zones are controlled with a Hunter wifi enabled programmable and Hunter valves and the heads are Rainbird 5000 series rotary.

 

[npalen]

How are your zones controlled and how are they scheduled....And is there well recovery time between watering zones....

I've tried various methods, over the years, of timing the zones including recovery time but it seems to make no difference. The well will produce 10 GPM 24/7 but no more even after several hours recovery and then pumping for, maybe, ten minutes. I'm happy to have 10GPM, just need to be able to control it.

I tried this valve back in the 70's but could not control the flow as it was erratic. The 1" size is probably too large for 10GPM?

 

[LouNY]

When adjusting valves the method of adjusting needs to be consistent all the time, either closing all the way and opening a set number of turns, or opening all the way and closing some many turns. Trying to adjust by opening and closing the slack in the actuator will affect the flow.
A pressure regulator will not control flow.

 

[steve tym]

How about a flow control, like a Dole flow control?

https://www.rcworst.com/Shared/content/mfr/eaton_corp/docs/dolevalve_specifications.pdf

 

[npalen]

How about a flow control, like a Dole flow control?

https://www.rcworst.com/Shared/content/mfr/eaton_corp/docs/dolevalve_specifications.pdf

Yeah, a flow control is probably the answer and that is what I've been using, it's just not precise enough with the 1" ball valve. It gets a bit confusing thinking about how the number and nozzle sizes of the sprinklers on each zone and trying to regulate the flow. One of the zones has only two heads so I do run larger nozzles on them while the five head zones all run the 2.0 GPM nozzles.
I'm probably overthinking it, but almost seems like both a pressure and flow regulator are needed but I'm not sure which would be upstream and which downstream of each other.

 

[etpm]

How about a flow control orifice before each zone and one pressure regulator feeding the whole system? That way each zone gets the same amount of flow to it no matter how many sprinklers. This assumes that each zone uses the same amount of water. I have done what you want but on a much much much smaller scale for lubricating a machine. I used constant pressure to the system and orifices at each lube point. This made it possible to deliver precise amounts of oil everywhere.
Eric

 

[npalen]

How about a flow control orifice before each zone and one pressure regulator feeding the whole system? That way each zone gets the same amount of flow to it no matter how many sprinklers. This assumes that each zone uses the same amount of water. I have done what you want but on a much much much smaller scale for lubricating a machine. I used constant pressure to the system and orifices at each lube point. This made it possible to deliver precise amounts of oil everywhere.
Eric

That seems to make sense and might work.

I'm beginning to think that my problem is that the six 1" zone valves are too large and that I should have gone with 3/4" or even 1/2" size. I say this because the 10GPM that I'm trying to achieve doesn't generate enough pressure to keep all the valves closed tightly except the one that is currently energized to run a zone. When that happens there are a couple dozen sprinkler heads trying to run on 10GPM resulting in not much more than a trickle from each.

 

[npalen]

Thinking about this some more and may have come up with a solution after remembering that there is a delay setting available in the Hunter controller software, called Hydrawise, that allows for a delay between the pump starting and a zone valve opening. I'm thinking that this might let the pump build up pressure against all the valves to keep them shut while the valve, that the controller calls for, gets opened by its solenoid.

The is no check valve on the pump so the water in the output line drains back into the well each time the pump shuts off.

This system was originally set up with the six zones but controlled with manual valves since 1976 until three years ago when we installed the controller. The last two years of drought have reduced the well output to where I have had to throttle the pump output pump down.

I will plan to add the time delay mentioned above and report back here to let you guys know how it works out. I very much appreciate all your feedback.

Edit: This short video shows how the zone valves work. It takes pressure to hold the valve closed which sounds counterintuitive.

 

[steve tym]

Pressure regulator first, flow control second.

 

[steve tym]

That seems to make sense and might work.

I'm beginning to think that my problem is that the six 1" zone valves are too large and that I should have gone with 3/4" or even 1/2" size. I say this because the 10GPM that I'm trying to achieve doesn't generate enough pressure to keep all the valves closed tightly except the one that is currently energized to run a zone. When that happens there are a couple dozen sprinkler heads trying to run on 10GPM resulting in not much more than a trickle from each.

I don't think a smaller zone valve will cure that.

 

[steve tym]

Be careful dead heading the pump.
The pump may make enough pressure to blow stuff up.
The motor is water lubricated and water cooled. It needs to have water flowing past it to keep it cool.
If there is no water flowing thru the pump long enough, it will melt the guts of the pump.

 

[Egon]

For flow control use a globe valve Or a fixed/variable orfice type valve.

 

[npalen]

Be careful dead heading the pump.
The pump may make enough pressure to blow stuff up.
The motor is water lubricated and water cooled. It needs to have water flowing past it to keep it cool.
If there is no water flowing thru the pump long enough, it will melt the guts of the pump.

Good advice. I'm always careful to not knowingly deadhead the pump for more than a few seconds but, between my wife and I, we have inadvertently left it running with no outlet flow for at least a few minutes on occasion over the last 48 years. The pump has been replaced once in that timespan. I've checked the amperage draw, out of curiosity, with the pump deadheaded and its interesting that the amperage drops way down.

I started this thread asking about a better method of controlling the flow and I still want to achieve that and certainly appreciate all the suggestions. After a lot of additional thought, however, I think that I need to solve the basic problem that being throttling the flow down low enough to not overload the well has resulted in not enough initial flow and resulting pressure to hold all six zone valves shut tightly until pressure builds up in the system.

To further explain, I can start the pump then pinch the flow down to the 10 GPM with the 1" ball valve and the pressure will hold the remaining five valves shut. But, when restarting the pump and opening one valve simultaneously, the 10 GPM can't overcome the leakage letting several more of the valves not completely shut. So I'm thinking that starting the pump and delaying the valve for a couple seconds may solve my problem.

Sorry for the wordiness here, I'm impressed if you're still with me.

 

[WranglerX]

Personally I think you are beating a dead horse in trying to throttle down the output of well/pump when it would be my concept to develop well more ..... But then my experience is with a 468 foot well (though almost 400 feet of solid granite) and 13 watering zones and the household to boot, all on a pressure tank system......... And my sprinklers/zones are only operational at night (no or little household use) and about half my zones run on odd days and other half on even days.......

 

[npalen]

Personally I think you are beating a dead horse in trying to throttle down the output of well/pump when it would be my concept to develop well more ..... But then my experience is with a 468 foot well (though almost 400 feet of solid granite) and 13 watering zones and the household to boot, all on a pressure tank system......... And my sprinklers/zones are only operational at night (no or little household use) and about half my zones run on odd days and other half on even days.......

I'm interested to hear your thoughts on "develop well more".

The driller hit a rock at 31' depth back in 1976 and we called it good with a depth to water of just over 21'. I initially installed the six zones all teed together and with a manual 1/2" valve next to each of the two dozen heads. Money was tight so no controller until three years ago.

I can live with the 10GPM during the rare drought years by running 2.0 GPM nozzles but controlling the flow can be a balancing act. I think there is a reason why controller features include a set time delay between pump start and valve opening and that can or may be utilized when the allowable flow rate is low.

 

[WranglerX]

I'm interested to hear your thoughts on "develop well more".

The driller hit a rock at 31' depth back in 1976 and we called it good with a depth to water of just over 21'. I initially installed the six zones all teed together and with a manual 1/2" valve next to each of the two dozen heads. Money was tight so no controller until three years ago.

I can live with the 10GPM during the rare drought years by running 2.0 GPM nozzles but controlling the flow can be a balancing act. I think there is a reason why controller features include a set time delay between pump start and valve opening and that can or may be utilized when the allowable flow rate is low.

Gee a rock at 31 feet and driller quit?..... 31 Feet here is not even surface water...... Suggest you talk with local geologist/hydrologist and see where other local wells are and who drilled them..... Locally here a "a rock" is just something to be drilled through..... Well report at time of drilling says my 468 foot well will go 300 gallons a minute using a air lift to test well (NOTE: I have my doubts as well was drilled 1991 long before I got property) ... And I only got a copy of well report in 2008 when I bought property, but at that time (2008) well was tested at 15 GPM and no appreciable decrease in level of water.... Suggest you explore local water tables and possible adding bulk water storage (2000-3000 tank) and second pump to disturbed stored water.... With large storage you can throttle back well pump and let tank fill at a rate the will not stress well and lever of water in tank would be controlled with simple float switch....