keep pump running at high pressure with pressure switch

[Reach4]

If you end up redoing stuff, and you have the ability to run power into the lake, consider a submersible pump. A 1 HP submersible will generally supply water better than a 2 hp above-water pump.

If you want an irrigation pump that can produce higher pressures, they also have multi-stage above ground irrigation pumps for that. They put two or more centrifugal impeller sections in series. Or maybe your pump already has more than one stage. In that case, consider a pump with more stages.

I guess the thing I am not addressing is how things worked satisfactorily for a good while before the problem. You can address some of the questions, and maybe post that photo.

 

[Fitter30]

Brand and pump model number then we can lookat a pump curve to see what the pump is supposed to do.

 

[Sponsor]

 

[RTL]

Can you just connect the pump to the pump start relay in the irrigation timer? 90' is the same as 40 PSI, so it will have to start higher than 40 PSI, which is hard to do with a pump than only makes 52 PSI. With 40 PSI loss up the hill I don't see how the sprinklers are working. Usually the 40 PSI elevation is added to what the sprinklers need.

I'm sorry I accidently said 90 ft of head. It is 60 so I'm losing about 26 psi on vert head and the pump is 75 psi 2 HP and tops out at about 51 psi on the gauge. Then it slowly bleeds down to 29 and kicks back in. p tank is at 28. I run water taps off this lake supply, so I need a pressure tank, but the sprinklers need the pump running at full capacity and to stay on. So the question I have is what is the best way to keep the pump running for the irrigation. Can I use a pump relay in conjunction with the pressure tank and how would I wire that or any other ideas?

 

[RTL]

90 feet of vertical rise, is the same as ~38 psi pressure reduction. As the pump can barely produce only 53 psi, the maximum pressure at the sprinkler head 90' above the pump will be only 15 psi. Since most pressure switches are calibrated for 20 psi differential between cut out and cut in, the pressure at the sprinkler head at the highest elevation will be a negative pressure until some time after the pump is activated and building pressure.
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I'm sorry I accidently said 90 ft of head. It is 60 so I'm losing about 26 psi on vert head and the pump is 75 psi 2 HP and tops out at about 51 psi on the gauge. Then it slowly bleeds down to 29 and kicks back in. p tank is at 28. I run water taps off this lake supply, so I need a pressure tank, but the sprinklers need the pump running at full capacity and to stay on. So the question I have is what is the best way to keep the pump running for the irrigation. Can I use a pump relay in conjunction with the pressure tank and how would I wire that or any other ideas?

 

[RTL]

Yes. If you want 40 PSI at the sprinklers and you lose 38 PSI on the hill getting up there, you need a pump that can supply the water you need at 78 PSI.

I'm sorry I accidently said 90 ft of head. It is 60 so I'm losing about 26 psi on vert head and the pump is 75 psi 2 HP and tops out at about 51 psi on the gauge. Then it slowly bleeds down to 29 and kicks back in. p tank is at 28. I run water taps off this lake supply, so I need a pressure tank, but the sprinklers need the pump running at full capacity and to stay on. So the question I have is what is the best way to keep the pump running for the irrigation. Can I use a pump relay in conjunction with the pressure tank and how would I wire that or any other ideas?

 

[Valveman]

So the question I have is what is the best way to keep the pump running for the irrigation. Can I use a pump relay in conjunction with the pressure tank and how would I wire that or any other ideas?

If you bypass the pressure switch you will have high pressure on small zones, but it will work. But still, this is EXACTLY what a Cycle Stop Valve was designed to do.

 

[RTL]

If you bypass the pressure switch you will have high pressure on small zones, but it will work. But still, this is EXACTLY what a Cycle Stop Valve was designed to do.

Will the cycle stop valve keep my pump from turning off at 51 psi? Sam must be your brother and I think he told me that the CSV will lower my psi by ~5 psi.

 

[Valveman]

Sam is my son. Thanks for the compliment. Lol! And yes the CSV will have maybe 5 PSI of friction loss when needing all the water you can get from that pump, which is never. But when the pump is cycling on and off you are not using all the water that pump can produce, which is why it is cycling on and off. So, the CSV will add more than 5 PSI friction loss as needed. It will add as much friction loss as needed to keep the pump from reaching 51 PSI and shutting off. All you have to do is set the CSV to hold about 45 PSI on the sprinklers, and the CSV will keep the pressure at 45 PSI. Only when you finally turn off the sprinklers will the CSV let 1 GPM fill the tank to 51 and the pump shut off.

 

[RTL]

Sam is my son. Thanks for the compliment. Lol! And yes the CSV will have maybe 5 PSI of friction loss when needing all the water you can get from that pump, which is never. But when the pump is cycling on and off you are not using all the water that pump can produce, which is why it is cycling on and off. So, the CSV will add more than 5 PSI friction loss as needed. It will add as much friction loss as needed to keep the pump from reaching 51 PSI and shutting off. All you have to do is set the CSV to hold about 45 PSI on the sprinklers, and the CSV will keep the pressure at 45 PSI. Only when you finally turn off the sprinklers will the CSV let 1 GPM fill the tank to 51 and the pump shut off.

I have a CSV125 30-3 that I was going to use with the smaller 1.5 HP pump, but Sam said it wouldn't work due to the loss in psi. Which one do I need to set a 45 psi? How is it adjusted? I have 1-1/4. Directly after the pump I have a check valve, then all of the pressure stuff, so where do you locate the CSV?

 

[Valveman]

There is almost no pressure loss in the CSV125 models. But the 30-3 means it has a 30 PSI spring and is designed to only give you 30 PSI no matter how little water you are using. There is no adjustment with that model. They come in 30, 40, 50, and 60 PSI. The check valve should probably be before the pump, but it will work after the pump as well. Depends on what you are drawing water out of.

You can get a CSV125 50-3 and have 50 PSI for the sprinklers. However, for the CSV to give you 50 PSI and use a 40/60 switch, the pump must be capable of at least 70 PSI max.

 

[RTL]

There is almost no pressure loss in the CSV125 models. But the 30-3 means it has a 30 PSI spring and is designed to only give you 30 PSI no matter how little water you are using. There is no adjustment with that model. They come in 30, 40, 50, and 60 PSI. The check valve should probably be before the pump, but it will work after the pump as well. Depends on what you are drawing water out of.

You can get a CSV125 50-3 and have 50 PSI for the sprinklers. However, for the CSV to give you 50 PSI and use a 40/60 switch, the pump must be capable of at least 70 PSI max.View attachment 94017

The Dayton Pump 5RWH0 has a 75 psi shutoff, but with the 60 foot of head it still creates 51-52 psi @ the pump. Will a 50 psi CSV work or do I need something lower? The pump is 2HP, so are you advising the CSV125-3 or the CSV125-1

 

[Valveman]

The specs on that pump say it will do 36 GPM at 50 PSI. You will lose maybe 5 PSI to friction loss in the CSVS125 at 36 GPM flow. So, you should get your 45 PSI at 36 GPM. If you go up 60' in elevation you will lose 25 PSI before the water gets there.

What I am not sure about is that 75 PSI shut off pressure. The next line say 147' max head which is only 63 PSI. I think the 63 PSI max for a sprinkler pump sounds about right. If the pump has a max pressure of 63 PSI you will need to use the CSVS125-3 in 50 PSI and shut the pressure switch off at about 55 PSI. A 35/55 switch is cutting it pretty close for a pump that maxes out at 63 PSI. If the pump can really do 75 PSI it would be much better.

 

[RTL]

The Dayton Pump 5RWH0 has a 75 psi shutoff, but with the 60 foot of head it still creates 51-52 psi @ the pump. Will a 50 psi CSV work or do I need something lower? I put the check valve on the output side of the pump thinking the head pressure was pretty high. Looks like the CSV goes before the pressure switch and tank

The specs on that pump say it will do 36 GPM at 50 PSI. You will lose maybe 5 PSI to friction loss in the CSVS125 at 36 GPM flow. So, you should get your 45 PSI at 36 GPM. If you go up 60' in elevation you will lose 25 PSI before the water gets there.

What I am not sure about is that 75 PSI shut off pressure. The next line say 147' max head which is only 63 PSI. I think the 63 PSI max for a sprinkler pump sounds about right. If the pump has a max pressure of 63 PSI you will need to use the CSVS125-3 in 50 PSI and shut the pressure switch off at about 55 PSI. A 35/55 switch is cutting it pretty close for a pump that maxes out at 63 PSI. If the pump can really do 75 PSI it would be much better.

The gauge if accurate shows the pump max psi at 51-52 psi, so I can't set the switch to 55. Will the 50 psi csv-3 still work?

 

[Valveman]

You will have to turn the switch up or bypass it to see how much pressure the pump can build. I think 63 or 147' is right and the 75 is the max rating of the pump seal.

 

[RTL]

You will have to turn the switch up or bypass it to see how much pressure the pump can build. I think 63 or 147' is right and the 75 is the max rating of the pump seal.

The switch is set just below what the pump produces already. Gauge says 52

 

[Valveman]

Don't know how you would know that without bypass the switch to let the pump dead head for a minute? Specs say 147' which is 63 PSI max.

 

[RTL]

Don't know how you would know that without bypass the switch to let the pump dead head for a minute? Specs say 147' which is 63 PSI max.

If I turn the pressure switch up o 53 the pump doesn't turn off

 

[Reach4]

The Dayton Pump 5RWH0 has a 75 psi shutoff, but with the 60 foot of head it still creates 51-52 psi @ the pump.

https://www.grainger.com/ec/pdf/Dayton-Cast-Iron-Lawn-Sprinkler-Pumps-Data-Sheet.pdf

For some pumps, the specification sheet shows what the pump does when sucking from different depths. Here we have a single number. Is that curve generated while the pump is sucking from 25 ft down? I suspect not.

 

[Valveman]

The Dayton Pump 5RWH0 has a 75 psi shutoff, but with the 60 foot of head it still creates 51-52 psi @ the pump. Will a 50 psi CSV work or do I need something lower? The pump is 2HP, so are you advising the CSV125-3 or the CSV125-1

I don't understand where the 60' of head is added on? It can't be sucking from 60' down. If there is 60' of head after the pump, the pressure at the pump should still be 63 according to the 147' max head in the specs.

But no, a CSV at 50 PSI cannot deliver 50 PSI unless the pump can make about 63 to 70 PSI at deadhead so a 35/55 pressure switch will work. Those irrigation or sprinkler pumps are made to give high volume at low pressure and don't work well with a pressure switch. Jet pumps or multi-stage centrifugals make a lot more pressure.

 

[RTL]

I don't understand where the 60' of head is added on? It can't be sucking from 60' down. If there is 60' of head after the pump, the pressure at the pump should still be 63 according to the 147' max head in the specs.

But no, a CSV at 50 PSI cannot deliver 50 PSI unless the pump can make about 63 to 70 PSI at deadhead so a 35/55 pressure switch will work. Those irrigation or sprinkler pumps are made to give high volume at low pressure and don't work well with a pressure switch. Jet pumps or multi-stage centrifugals make a lot more pressure.

The gauge says 52 psi. I just need the pump to stay running when the sprinklers are on. Can a pump relay be run by both a pressure switch and a relay and how do you wire that?