Well pump size recommendation

[wileydog]

Hi all, new to site. Replacing an existing well pump and wanted to ask if anyone has recommendations on what I should put in there. This is not a well, it is a 1,000 gallon cistern that is feed by city water. It is located at the bottom of a hill and feeds water to the house via pump. Elevation from pump/cistern to house is approximately 130 feet with total pipe (1 inch) of around 700 feet. It feeds the house, a shop and garden...approximately 22 fixtures. If I calculated correctly, I come up with TDH of 338.9

Not sure what pump is in there currently (recently purchased home, have not yet moved in), however, current pressure and flow is too low at the house and original wire was 10-2 all the way to the pump (pump is currently 220/2 wire). Switch and around a 5 gallon pressure tank is under the house. I put in new pipe to the tank and upgraded the wire to 2-2-2-4 to pretty much put anything I want in there (wire is installed, but not yet hooked up, still on old wiring). Would like to bring up the pressure and flow capability as I believe the pump currently in place is insufficient.

I plan to put in a CSV as well. Currently, I'm looking at a 1.5 HP 20GPM Franklin 3 wire pump, upgrade to a 20 gallon pressure tank (largest that will fit), replace switch and install a controller (should this be at house or next to cistern?)....does that sound about right?

Just want to make sure I'm calculating the required pump size correctly before I purchase, have never been on pump before.

Thanks for any feedback, recommendations!

 

[Valveman]

At 10 GPM there should only be about 15 PSI (35') loss in 700' of 1" PVC. With 130' of lift, 30' friction loss, and 50 PSI (115'), that would be a total head of 280'. If you add much more for friction loss the pressure at the house will be much higher when using less than 10 GPM.

 

[Sponsor]

 

[wileydog]

Thanks for the reply, so you would recommend a 10GPM pump rather than the 20GPM I was thinking to put in? I am feeding a shop (located another ~100 feet from the house with bath and shop sink, and a garden (around 1 acre)....The PVC that I had put in can handle quite a bit of back pressure and the CSV would control pressure into the house...right??

 

[Valveman]

At 20 GPM you would have 7.5 feet per second velocity and about 60 PSI in friction loss. It can be done, but is way more than you should put through 1" pipe. The house and shop won't need 5 GPM. The total volume needed depends on how you plan to irrigate? Garden hoses and a couple of 3 GPM sprinklers at a time would leave you another 5 GPM for the house and shop, so 10 GPM pump should be plenty. But if you want to use 20 GPM to irrigate, you would need a larger pump, which would be wasting energy to shove that much down 1" pipe. But I can do it if you want, just need some pressure reducing valves at the house and shop. One acre is a pretty good size garden. But you can water it all in a couple of hours or start early and stay late to get watered across? Drip, spray, or flood?

 

[wileydog]

OK, again, thanks for the quick reply and additional info....I was thinking 1.5 HP, would that be sufficient? Don't mean to ask uninformed questions, but have never worked with a well pump before.

Again, appreciate the education!

 

[Valveman]

For 10 GPM at 280' a 3/4HP will nearly do it. But you will need a 1HP, 10 GPM submersible to get there.

For 20 GPM at 418, you would need a 3HP, 20 GPM submersible, and a pressure reducing valve at the house and shop.

 

[wileydog]

Again, thank you for the input, very helpful!