Pressure Tank Size

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by jed1154, Jan 22, 2020.

  1. jed1154

    jed1154 Member

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    Location:
    Texas
    Hey, since my small 1.5HP submersible (No idea what actual size) is in 20' of water and pumping back to the pressure tank in 1" SCH40 PVC, why am I not worried about blowing up the PVC pipe in that one like the concern before with the 50gpm?
     
  2. Reach4

    Reach4 Well-Known Member

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    Location:
    IL
    1.5 hp pump seems excessive. Your 1.5 hp pump could generate too much pressure. Why would a 1/2 HP 10 gpm pump not be a better fit for your pressure pump to the house?

    You would not want to thread schedule 4o pipe. Are you talking glued pipe?


    [​IMG]

    Put a flow inducer on the pump. It is simple and cheap. Pump down switch turns this pump off if cistern is low. In series with pressure switch.

    Pump up switch controls what you need to do to limit filling the cistern, if that process is automated.
    [​IMG]
     
    Last edited: Feb 4, 2020
  3. valveman

    valveman Cary Austin Staff Member

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    The concern about the 50 GPM pump was just imagined, not a real problem. A 1.5HP, 20 or 25 GPM pump can only build 138 PSI. But you could have a concern if it is a 10-15 GPM series pump, as they will build a lot of pressure.
     
  4. jed1154

    jed1154 Member

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    Simple. Because the pump listed is not what I have. LOL.

    The pump is what was taken out of the well that now has a 50gpm. This was installed by the driller once he understood what we wanted to accomplish. It's PVC down to the pump and we have float switches like in your post.

    Its easy to pull this pump by hand if we have problems.
     
  5. Reach4

    Reach4 Well-Known Member

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    Expect your pump to have two labels -- one on the motor part, and one one the "wet end". What does the one on the wet end say, particularly model number and gpm if present.
     
  6. jed1154

    jed1154 Member

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    Im hoping to get this info today. I'm pulling it. Ill post back as soon as I have the info.
     
  7. Reach4

    Reach4 Well-Known Member

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    This removed 1.5 HP pump currently is in service in another job, I think you are saying.

    A 1/2 HP 10 gpm pump is perhaps the cheapest submersible pump you can buy.
     
  8. valveman

    valveman Cary Austin Staff Member

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    Since your pulling it anyway, you can always put a 1HP, 3/4HP or 1/2HP wet end on that 1.5HP motor if needed. I am guessing it will be a 10 GPM series 1.5HP which will build way more pressure than you need as they are designed to pump from pretty deep wells.
     
  9. jed1154

    jed1154 Member

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    Ill get the model numbers.
     
  10. jed1154

    jed1154 Member

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    Pump inside cistern is on SCH 80 1.25" Pipe and in no more than about 18' of water.

    Franklin 2145089009
    Grundfos 10S10-15, 1HP 10 USGPM

    EDIT: To correct Grundfos Model Number
     
    Last edited: Feb 11, 2020
  11. Reach4

    Reach4 Well-Known Member

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    10S10-15
     
  12. valveman

    valveman Cary Austin Staff Member

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    Yeah that pump will build 250 PSI. Plus it needs a minimum of about 100 PSI on it to keep from upthrusting. You could use a 10 GPM Dole valve, but even those are only good to 125 PSI differential. Best to put a 25 GPM pump end or 10 GPM, 3/4HP pump end on that 1.5 HP motor. Then the pump will be working in a good spot on the curve when using a 40/60 switch.

    Another idea is to use two of the CSV1A valves. Two are needed to stair step the pressure down from 250 to 50 without wearing out the CSV. Plus the second CSV1A will add enough friction loss that it will keep the pump from upthrusting. But you would only need one CSV1A with the 25 GPM pump end or the 10 GPM, 3/4HP pump end.
     
  13. LLigetfa

    LLigetfa DIYer, not in the trades

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    Put an in-well CSV directly on the pump outlet and the PVC pipe won't see holdback pressure.
     
  14. jed1154

    jed1154 Member

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    Any way to do this with ONE CSV? Just not enough money leftover in this project after water filtration requirements to do it otherwise. I may have to just use it as is for a while.

    This pump/motor pumps water from 20 feet in the ground up to ground level and then about 100' in 1.25" PVC to the pressure tank, if that changes anything.
     
    Last edited: Feb 11, 2020
  15. Reach4

    Reach4 Well-Known Member

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  16. valveman

    valveman Cary Austin Staff Member

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    I would not use a pump that was made for 500' to pump from 20'. You would be much better off selling that pump to someone that needs it and get a smaller pump for the cistern. You can get a 1HP, 33GPM Hallmark for about 150 bucks. Even that cheap pump would be better than using the wrong size pump.
     
  17. jed1154

    jed1154 Member

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    I understand. Unfortunately, there were some unforseen issues with this project that blew the budget here. A new well pump is simply not going to happen when we have a perfectly functional pump in it now.
     
  18. valveman

    valveman Cary Austin Staff Member

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    That $150 pump would save you a lot of hassle and electricity. You should be able to sell that deep well pump for much more than that. Those are expensive pumps for someone who needs it.
     
  19. jed1154

    jed1154 Member

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    Feb 11, 2008
    Location:
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    It's no hassle. It's powered. It's plumbed. We fill up the tank and literally flip a switch. That's why we aren't changing it. We have a 1HP 10GPM pump....but I'm being advised to pull that and change it to a 1HP, 33GPM Hallmark for about 150 bucks??

    This makes zero sense to me. Anyway, like I said, I don't make the call and there is no way anyone is onboard with that decision as this is ready to go as is. The well installer did this work a a few years ago and they did all of the consulting with their 'pump book'. These guys are quite well respected locally so again, I'm not going to convince anyone this is 'bad'. Good news is pumps are cheap and in stock at tractor supply if it blows up!
     
    Last edited: Feb 19, 2020
  20. valveman

    valveman Cary Austin Staff Member

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    Pump Controls Technician
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    Makes perfect sense! Your 10S10-15 is designed to work in a 300' deep well. Pumping from a storage tank that 1HP will only deliver abour 12 GPM max. Because there is no lift a 1HP can easily pump 33 GPM for the same electric bill. But you need a 33 GPM pump end on that 1HP motor to make that happen. Plus with the 10S10-15 pump you need a Dole valve to hold back about 100 PSI to make that pump think it is at least 100' deep to keep it from being damaged by upthrust. I understand wanting to use what you already have, but that is like putting a huge window unit air conditioner in a VW Bug.
    window AC car.jpg
     
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