Problem with Shurflo pump

lazzalazza Solar Expert Posts: 330 ✭✭✭
HI Forum

A while ago we sold a Shurflo pump: http://www.solar-electric.com/2088-514-145.html . However it wasnt working so we went to have a look.

Basically although they told us that the pump would be installed at the water level, it is in fact 2 or 3 metres above the water level and about 2 metres from the shallow well which it will draw from. We did some tests and from a bucket just next to the pump it could easily raise the water the 20m that it needs to go to the water tank. However, when the inlet pipe is dropped into the shallow well, it wont suck the water in.

What would you guys recommend as the solution? Are there more powerful pumps that could overcome this inlet problem?

Cheers
Larry

Comments

  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Problem with Shurflo pump

    "Self priming up to 12 feet" Seems like you might be right on the edge of that specification. That pump is supposed to have a backflow preventer in it. I wonder if you could get it primed, and the pipe between the pump and the water source full, if it wouldn't start working.
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Re: Problem with Shurflo pump

    I'm working on very old memories from doing research years ago on a survival pump for drawing water from a river, but...

    There is a total work thing also (the engineers around here will love this explanation) While it may be able to pull water up 12 feet, and push water 40 feet, it might not be able to do both. There is some ratio of push and pull (3:1?) that the pump can do... so it's something like push/3 feet + pull feet can't be greater than perhaps the 12' Volvo Farmer is talking about...

    OK slam me, it's too early for me to hunt around to put this in proper terms. Sorry.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • icarusicarus Solar Expert Posts: 5,248 ✭✭✭✭
    Re: Problem with Shurflo pump

    It will be able to push water to ~60 psi (over 100 vertical feet). The problem is probably that have too much friction on the suction side and or a suction side leak, which is much harder to find. I have had this problem before with shurflos. They will pump fine elevated 5' from the water, but move the pump 100' inland AND elevate it the 5' and it would not pump reliably. I was able to get one to pump in a beta test, went ahead and installed the pump in the house, (at the same location) and could never get it to prime, even installing a prim port, and a foot valve. I had to finally move the pump closer to the source.

    I suggest you figure out how to move the pump closer to the source, and possible run it on a linear current doubler, increasing the voltage for 12 to 24 to add reduce current loss between the poer source and the pump. Check with shurflo that it is gng to e ok to run on 24, some can other may not.

    Good luck and keep in touch,

    T
  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Problem with Shurflo pump

    Had a thought last night.

    If we put 2 of the same pumps in parallel, with a Y juntion before the inlets and a Y junction after the outlets, would this improve the aspiration (suction of the pump).

    Or in series? I know that this will improve the head, but will it improve suction? :confused:
  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    Re: Problem with Shurflo pump

    My guess is the pumps will become less stable with the Y on the inputs. It is better to let them each have their own input... The are very sensitive to vacuum leaks.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peakbaggerpeakbagger Solar Expert Posts: 341 ✭✭✭
    Re: Problem with Shurflo pump

    Generally pumps are rated for some many feet of suction head. Open to atmosphere, the suction head is the elevation difference between the top of the water and the center line of the pump inlet plus the frictional loss in the pipe and fittings. A lot of bends or check valves can eat up a lot of head.

    There is also a different term, Net Positive Suction Head which can be an issue, normally with hot liquids at lower than atmospheric pressure. It tends to be ignored

    http://www.engineeringtoolbox.com/npsh-net-positive-suction-head-d_634.html

    Most commercial pumps have established a NPSH required for each pump. It rare to see this specified for retail pumps. If the NPSH is insufficient it can trash a pump quick and usually its sounds like someone is running gravel through the pump. About the only this you have control of is the suction head so move the pump closer to the supply.
    If the pump is borderline and you can relocate it, about the only option is check on the suction strainer and install a prime tee on the suction.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Problem with Shurflo pump

    can you install a 12 or 24 V submersible as the prime pump and leave the existing on to provide pressure/lift?
     
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  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Problem with Shurflo pump
    westbranch wrote: »
    can you install a 12 or 24 V submersible as the prime pump and leave the existing on to provide pressure/lift?

    This would be a kind of ideal situation, but only if I can find a low-power, very cheap submersible prime pump--- do these exist?
  • icarusicarus Solar Expert Posts: 5,248 ✭✭✭✭
    Re: Problem with Shurflo pump

    Shurflo makes a nice 12/24 volt submersible. Not really cheap, but robust and reliable. Also do a search for well monitoring small submersibles used by well testers. Pretty cheap, but won't pump into high pressure very well.

    I have had a shurflo submersible in the lake for 7 years now with no trouble. Goes through the winter just fine, and delivers ~ 2 gpm into 60 psi.
    http://legacy.shurflo.com/pages/new_industrial/Industrial/agriculture/subcategories/9300.html


    http://www.solar-electric.com/sh93susowapu.html

    Tony
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