New well installation

[Cookieman]

Hello everyone, I'm a newbie here, lots of great information so I thought I would get some opinions on a new well pump install and set up.
Here are the well specs.
400' deep
100' to static water level
3 gallons a minute
The installer is going to put in a 1 1/2 10gallon a minute pump at 380'
Single family home with a total fixture count of 15
I was wondering what size pressure tank to go with paired with a cycle stop valve.
Also do you think the pump gpm is too small. It will push more gpm early due to the high static level right?
I trust the installer he drilled the well and has been in the business for years.
Thanks

 

[Valveman]

I would use a 12 GPM Dole valve in front of a PK1A Pside-Kick kit, which comes with the CSV1A and a 4.5 gallon size tank. You have at least 450 gallons stored in the well. A larger pressure tank is not going to help and in fact will act like an additional load for the well to supply.

 

[Sponsor]

 

[Reach4]

This table shows the GPM that a 1.5 HP 15 GPM pump will produce into a given PSI surface pressure.

What does a Dole valve add to the system?

 

[Valveman]

I agree the 15 GPM, 1.5 HP would be less likely to upthrust when the water level is at 100'. But that pump would only deliver about 20 PSI when the water pulls down to 380'.

The 10 GPM, 1.5HP will need a Dole valve to keep form upthrusting when starting with a 100' water level. I said 12 GPM just for some cushion, but you could use a 15 GPM Dole valve. Anything over 15 GPM is bad for the pump.

I would probably just use a 1HP, 10 GPM pump. It will still build pressure from 380', and won't upthrust when starting at 100' pumping level.

 

[Reach4]

I think I got my eyes crossed there. Here are tables for 10 GPM pumps. He might be safe with 1.5 HP if the pressure switch was at 50/70 PSI or even 40/60 PSI, but I see that the 1 HP that you suggested is better. While the pressure would drop if the water level got low, that could be a very good thing IMO. For example, suppose the well dropped to 360 and the well only provided 3 GPM at 20 PSI. It seems to me that beats having a pump that will provide 8 GPM until the well runs dry. This table is for a particular pump family, and the numbers could differ a bit from brand to brand or model to model.

 

[Cookieman]

Cool, the installer did offer a 1hp pump but I was not looking at the pressure curve with the full casing. So basically he was on top of it. My bad. I'll check into the cycle stop valve set up, just to clarify a larger storage does me no good?
Thanks

 

[Valveman]

just to clarify a larger storage does me no good?

Yes. Larger pressure tank is just an additional load on the already low producing well supply.

 

[Cookieman]

Great, thanks for the valuable information, just ordered the cycle stop. Installing in a week or so.