Did I purchase the wrong size pump?

[Planecrazy]

My challenge:

Not enough water pressure at pressure tank to engage the pressure switch (cut off). The pump stays on 100% of the time the power is on.


The following have been installed:

- Flotec FP5172 1.5HP Sprinkler Pump, running on 220/230 (18' vertical height above the creek)

- WaterWorker HT-20B Vertical Pressure Well Tank, 20-Gallon Capacity (24' vertical height above the creek)

- 1 x 11 Tank Tee Kit with VALVES Installation Water Well Pressure Tank SQUARE D 30/50 FSG2 pressure switch (1 x 11 Tank Tee Kit with VALVES Installation Water Well Pressure Tank SQUARE D 30/50 ... https://www.amazon.com/dp/B00TG27TGG/ref=cm_sw_r_sms_apip_3Em1FIYOj5e4D)


What is working:

I have enough water pressure to run 3 or 4 sprinklers at a time. The pump stays primed.


Pressure readings/settings:

- when I turn on the pump and run 3 sprinklers the tank/line pressure is 25PSI.

- when I turn on the pump and close the valves so water can only go into tank. The max line pressure is 35PSI.

- At 42PSI (factory pressure setting) the tank would not take on water. I reduced the air pressure at the tank to 20PSI. The tank takes on water.

- I believe I lowered the pressure switch setting to 20/40.


Here's where, I think, I need feedback.


1) Should I switch out the 1.5HP Flotec Pump with a 2HP pump? Maybe a Red Lion RLSP-200 2-HP 80-GPM Cast Iron Sprinkler pump. I don't have any reason to switch from Fluted, this just seems to be a popular pump and self primping to 25'.

2) Am I using the correct type of pump for this application?

3) Should I make adjustments to the pressure tank/switch so the system will work properly?

Thanks in advance for your feedback.

Update: I forgot to mention the total line of sight distance from the creek to the pressure tank is 80'.

 

[Reach4]

http://www.flotecpump.com/resources/images/527.pdf page 9 predicts 11 GPM at 20 ft above the water at 40 PSI. How many GPM is each sprinkler>

 

[Sponsor]

 

[Planecrazy]

http://www.flotecpump.com/resources/images/527.pdf page 9 predicts 11 GPM at 20 ft above the water at 40 PSI. How many GPM is each sprinkler>

I am currently using these sprinklers. I don't see GPM on the specs. http://www.homedepot.com/p/Orbit-Zi...-Circle-Sprinkler-Head-2-Pack-27901/100659289

These sprinklers are temporary. My future plan is to put in a "standard" irrigation system for a .4 acre yard.

Hope this information is helpful.

 

[Reach4]

See table on https://www.orbitonline.com/product...inkler/zinc-impact-on-aluminum-step-spike-170

 

[Planecrazy]

See table on https://www.orbitonline.com/product...inkler/zinc-impact-on-aluminum-step-spike-170

See table on https://www.orbitonline.com/product...inkler/zinc-impact-on-aluminum-step-spike-170

It looks like at 30 psi - 3.3GPM, 40 psi - 3.8GPM.

See table on https://www.orbitonline.com/product...inkler/zinc-impact-on-aluminum-step-spike-170

 

[Reach4]

It looks like at 30 psi - 3.3GPM, 40 psi - 3.8GPM.

So it should be clear now. That pump is not suitable for you to drive 5 of those sprinklers at the same time. Think zones or new pump.

 

[LLigetfa]

I would use a submersible. They are way more efficient and capable of higher pressures.

 

[Planecrazy]

So it should be clear now. That pump is not suitable for you to drive 5 of those sprinklers at the same time. Think zones or new pump.

Do you know where I can find the

I would use a submersible. They are way more efficient and capable of higher pressures.

Thank you for the feedback. My creek is pretty small and shallow. I should have mentioned this earlier. I'm concerned debris passing down the creek will get caught up on the submersible pump.

 

[LLigetfa]

- when I turn on the pump and close the valves so water can only go into tank. The max line pressure is 35PSI.

That rules out the problem being too many heads for the GPM rating. The 18 feet of lift is too close to the limit. You don't say how much horizontal run you have and if setting the pump closer to the water level is practical.

 

[Valveman]

Had to look hard top find the specs, and they still don't give the max pressure that pump can build. But from the crude chart it looks like from 18' of lift it will barely build 40 PSI. So you would need to run about 15/35 on the switch to make it work. A so called "sprinkler pump" will pump a little pressure to sprinklers, but it won't build enough pressure to work with a pressure switch. You need a jet pump as they will build the pressure needed for the pressure switch, and pumps don't know if they are delivering water to grass or people. Pumps are pumps, you just need one that delivers the right flow AND pressure. It doesn't have to say "sprinkler" on the pump.

 

[Planecrazy]

That rules out the problem being too many heads for the GPM rating. The 18 feet of lift is too close to the limit. You don't say how much horizontal run you have and if setting the pump closer to the water level is practical.

Thanks for your input.

About 45' of horizontal run from the creek to the pump.

 

[Planecrazy]

Update: after adjusting the pressure switch to 15/35. The pump is cycling on and off as desired. While the water pressure is lower than initially anticipated. The system will run approximately 3 sprinkler heads that use about 3.5GPM each. Going to upgrade to a 2HP motor in the near future. All of the feedback was helpful.

 

[Reach4]

Update: after adjusting the pressure switch to 15/35. The pump is cycling on and off as desired. While the water pressure is lower than initially anticipated. The system will run approximately 3 sprinkler heads that use about 3.5GPM each. Going to upgrade to a 2HP motor in the near future. All of the feedback was helpful.

Ideally, the pump would not cycle at all during the 3 AM watering. The pressure would stabilize between the switch limits, such as 30 PSI with your 15/35 switch. It is important that when the sprinkers turn off, the pressure can then rise above the cutoff pressure.

 

[Valveman]

Update: after adjusting the pressure switch to 15/35. The pump is cycling on and off as desired. While the water pressure is lower than initially anticipated. The system will run approximately 3 sprinkler heads that use about 3.5GPM each. Going to upgrade to a 2HP motor in the near future. All of the feedback was helpful.

Got to be careful with a larger pump or it will just cycle itself to death at low flows. Also a jet pump or multi-stage pump will build more pressure than a regular centrifugal pump. With a CSV you can use as large of a pump as you want, and the CSV will make it work like a small pump without letting it cycle itself to death.

 

[Planecrazy]

Ideally, the pump would not cycle at all during the 3 AM watering. The pressure would stabilize between the switch limits, such as 30 PSI with your 15/35 switch. It is important that when the sprinkers turn off, the pressure can then rise above the cutoff pressure.

Currently, when I run the sprinklers, after a minute or so, the pressure drops to below 15 and the pump kicks on. The pump stays on until about 1 minute after the valve to the sprinklers is closed.

 

[Planecrazy]

Got to be careful with a larger pump or it will just cycle itself to death at low flows. Also a jet pump or multi-stage pump will build more pressure than a regular centrifugal pump. With a CSV you can use as large of a pump as you want, and the CSV will make it work like a small pump without letting it cycle itself to death.

Would you mind sending me a link to the pump you would purchase. Thanks for your help.

 

[Valveman]

Would you mind sending me a link to the pump you would purchase. Thanks for your help.

Be glad to help. I looked up that pump, at 25 PSI it says 41 GPM? What kind of sprinklers are you running? Anyway they could be using 40 GPM?

 

[Reach4]

Currently, when I run the sprinklers, after a minute or so, the pressure drops to below 15 and the pump kicks on. The pump stays on until about 1 minute after the valve to the sprinklers is closed.

Sounds like you are tuned well to your current pump. How many PSI is there on the gauge after the sprinklers have been running for several minutes?

 

[Planecrazy]

Be glad to help. I looked up that pump, at 25 PSI it says 41 GPM? What kind of sprinklers are you running? Anyway they could be using 40 GPM?

Question: 25PSI, 41GpM - is this the Red Lion 2HP I mentioned or the Flotec 1.5HP pump I currently have installed?

I am running https://www.orbitonline.com/product...inkler/zinc-impact-on-aluminum-step-spike-170
From the chart a little over 3 GPM per sprinkler.

Eventually, I will install a true irrigation system. For now, I'm using hoses.

 

[Valveman]

Question: 25PSI, 41GpM - is this the Red Lion 2HP I mentioned or the Flotec 1.5HP pump I currently have installed?

I am running https://www.orbitonline.com/product...inkler/zinc-impact-on-aluminum-step-spike-170
From the chart a little over 3 GPM per sprinkler.

Eventually, I will install a true irrigation system. For now, I'm using hoses.

Yes I was looking at the 1.5HP you have now. And 3 GPM sounds more like it. So 3 sprinklers at 3 GPM is only 9 GPM. A 1HP jet pump like the Goulds J10S will pump 12 GPM at 50 PSI. A J15S would put out 17 GPM at that depth and 50 PSI. Lifting from that depth and needing 50 PSI, a jet pump will be much better.