New Well Drilled Yesterday! Pump Sizing Question

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Windward_coug

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Here's the background: I bought this property 4 years ago with an existing well. Here's the stats:

1005' Deep
80" Static water level
3 gpm flow tested
Water was hit at 980'
5gpm 2 horse Goulds pump

I had a 1500g cistern installed with a booster pump and it's worked okay the last few years. When people visit I've had some really bad luck with the system, there's been times the last few years that I've been hauling water for weeks at a time. I decided I wanted a supplemental well that could give me some redundancy and maybe be the main water source for my house and I could use my current setup for irrigation.

I made a road to the back of my property, it's about 500 feet long and 100 feet down. It ends just uphill of a dry creek. I got the good news from my driller yesterday.

210' Deep
30' Static Water level
35+ GPM, he said he hit a massive fracture
Water hit at about 190'

I'd like to set up a CSV for constant 60 psi. My TDH calculations show about 420 TDH. I plan on using 1.5" pipe from well to well house (~500ft). I think a Goulds 10gpm 2 horse pump would work well for my application. My house is pretty big, 4400 sq. ft with 4.5 baths, but a 10gpm pump should be fine right? I'm still in shock they found so much water, so shallow compared to my current well, hydrogeology is crazy.
 

Reach4

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10 gpm is plenty, and I doubt that you need 2 HP.

How much vertical rise from the well to the house?

What diameter is the well? A flow inducer sleeve is probably desirable.

Do you have a pitless adapter?

Where will the pressure switch and pressure tank be -- at the well or at the house? If at the house, the pressure drop from the well to the house falls out of the calculations.
 

Windward_coug

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10 gpm is plenty, and I doubt that you need 2 HP.

How much vertical rise from the well to the house?

What diameter is the well? A flow inducer sleeve is probably desirable.

Do you have a pitless adapter?

Where will the pressure switch and pressure tank be -- at the well or at the house? If at the house, the pressure drop from the well to the house falls out of the calculations.

The vertical rise from the well to the house is about 100 ft.

It's a 6 inch well with 4.5" casing.

The pitless adapter hasn't been installed yet.

The pressure switch and tank will be in a well pit about 400 ft from the well. The well pit is about 100ft from my house.
 

Valveman

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Won't argue with the 420' of head if the well pulls all the way down. But the pumping level in such a good producing well may not be much lower than static. I would figure maybe 150' pumping level, and that may be deep if only using 10 GPM or so. I would use an 18GS20 instead of the 10GS20. The 18 GPM will pump more water, cost less as it has fewer impellers, and have less back pressure when working with a CSV. Even with the 18GS20 the back pressure on the pitless and pipe prior to the CSV will be 180 PSI because of the high static level. The 10GS would work, but have 220 PSI back pressure.

To get 60 PSI constant I would use the PK1A with a 10 gallon tank and a standard pressure switch. The pressure switch setting would be 50/70 so the CSV can work at 60 PSI constant. I hope the vertical rise to the house is before the well pit? If not we need to add 40 PSI to the settings of the controls in the pit, and will need a larger tank.
 

Windward_coug

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Won't argue with the 420' of head if the well pulls all the way down. But the pumping level in such a good producing well may not be much lower than static. I would figure maybe 150' pumping level, and that may be deep if only using 10 GPM or so. I would use an 18GS20 instead of the 10GS20. The 18 GPM will pump more water, cost less as it has fewer impellers, and have less back pressure when working with a CSV. Even with the 18GS20 the back pressure on the pitless and pipe prior to the CSV will be 180 PSI because of the high static level. The 10GS would work, but have 220 PSI back pressure.

To get 60 PSI constant I would use the PK1A with a 10 gallon tank and a standard pressure switch. The pressure switch setting would be 50/70 so the CSV can work at 60 PSI constant. I hope the vertical rise to the house is before the well pit? If not we need to add 40 PSI to the settings of the controls in the pit, and will need a larger tank.
Thanks for the info. I'll have my well guy pump the well and see how much the level drops after an hour or two. You're probably right, it may not lower much at all with so much production. Luckily the vertical rise is to the well pit, so I should be good there.
 

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Test pumping the well is the best way to figure the pumping level. Otherwise you just have to get a larger pump to cover the bases. Test pumping will probably change all the numbers.
 

Reach4

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I would go with a 1.5 or 1.0 HP 10 gpm pump. I can't see that having a problem keeping up for a house.

index.php

Yes, the downpipe should be able to almost handle the deadhead pressure, and almost that much up to the CSV. With the 1.5 hp 10 hp, I can see where pressures would need further study. I have not worked the numbers, but I expect 1 inch 250psi SIDR pipe would be good. https://www.menards.com/main/plumbi...149-c-8570.htm?tid=6058390454891570388&ipos=6

With the 10gpm 1 HP, I am thinking 160 psi SIDR pipe maybe 1-1/4 (and maybe even 1 inch after checking the numbers), and put the CSV at the house with the pressure switch.
 
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Windward_coug

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I would go with a 1.5 or 1.0 HP 10 gpm pump. I can't see that having a problem keeping up for a house.

index.php

Yes, the downpipe should be able to almost handle the deadhead pressure, and almost that much up to the CSV. With the 1.5 hp 10 hp, I can see where pressures would need further study. I have not worked the numbers, but I expect 1 inch 250psi SIDR pipe would be good. https://www.menards.com/main/plumbi...149-c-8570.htm?tid=6058390454891570388&ipos=6

With the 10gpm 1 HP, I am thinking 160 psi SIDR pipe maybe 1-1/4 (and maybe even 1 inch after checking the numbers), and put the CSV at the house with the pressure switch.

The well driller just called me, he said he's going to double-check the static level tomorrow. He said that my well was actually doing well over 50gpm, just an eruption of water. It was making so much water that his rig was having a hard time drilling deeper because of the water pressure? Anyways, he agreed with you guys that a 10gpm pump would be my best bet. Thanks
 

Reach4

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Remember to watch the pressure before the CSV. Is he putting in PVC from the pump to the pitless, and polyethylene after the pitless?

Congratulations on the water. You will probably want a lab test on the water. You will probably want to pump to pump out sand.
 

Valveman

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Yeah with that static level even a 1HP in 10 GPM series will have 186 PSI back pressure. The 1.5HP would have 230 PSI back pressure. If the test pump shows the water level doesn't pull down much you may even be able to use a 3/4HP in 10 GPM series.
 

Windward_coug

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Yeah the plan is pvc from pump to pitless and then buried 1.5” pex to the well pit where the csv and pressure tank will be located. Yeah I’m hoping for minimum drawdown, a 3/4 hp pump would save on wire which is expensive right now.
 

Valveman

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Yeah the plan is pvc from pump to pitless and then buried 1.5” pex to the well pit where the csv and pressure tank will be located. Yeah I’m hoping for minimum drawdown, a 3/4 hp pump would save on wire which is expensive right now.
Just make sure the pipe before the CSV can handle 180 or 230 PSI depending on which pump you choose.
 

Reach4

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SIDR pipe is available in higher pressure ratings up to 250 psi. Also it is larger ID for a given nominal size than PEX. I think 1 inch SIDR polyethylene pipe would be big enough, but if not that, 1-1/4 would still give you more margin. If the pressure switch and tank are at the well head, then the bigger pipe would have more advantage. http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php is one of the available pressure drop calculators.

When you put in the pipe, do not pull tight. See page 87 ("77") of https://www.huduser.gov/portal/publications/pex_design_guide.pdf

While that names PEX, the same principle applies to other polyethylene.
 
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