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  • Which pump for a 20m deep well?
  • iolo
    Free Member

    I have a well in my garden as the area is very dry in the summer.
    I just shot a laser measurer down it and its about 20 m deep from the top of the well ring to the water level.
    I want to get water out of this for my garden but don’t want to have to manually crank the handle.
    Ideally, it would be used on a sprinkler system for my veg and fruits.
    Could anyone recommend a pump for this? Ideally, it would be run from solar panels as its very sunny here from now until September.

    wwaswas
    Full Member

    getting 60ft of head (missus) is quite a big ask for a solar powered pump, imo.

    you might need to run it off batteries and use the solar to charge those rather than direct from the solar but this one claims not…

    http://www.ebay.co.uk/itm/Great-24V-Submersible-Deep-DC-Solar-Well-Water-Pump-Solar-battery-alternate-/251984205453

    one_happy_hippy
    Free Member

    Several things I Learnt from having a water bore with pump as the only water supply for camp for 250km…:

    If you are drawing water constantly and the draw down rate is greater than the recharge rate then you run the risk of burning out your pump by inadvertently running it dry.

    If you don’t draw from far enough below the surface of the water so you can maintain a head of water above he base of the pipe (or pump if submersible) it can lead to surging and burning out of your pump.

    Ensure that the pump has slightly over capacity to lift the water the required head PLUS to push the water ever distance horizontally.

    If using a submersible pump make sure it has a stainless steel line attached to it anchored at surface.

    Drill a small (1-2mm or so) hole in the pipe directly above the pump. It turns out lifting water pipe with a pump attached that are both full of water is surprisingly heavy. The hole means you can lift it to just above water level, allow the pipe to drain and lift it with ease.

    1) Are you intending it to run constantly to provide a constant flow rate )to your garden)?

    2) What volume of water are you looking to extract and can you establish the draw down rate you will impose on the well.

    3) Can you establish the recharge rate of the well?

    iolo
    Free Member

    I just want to run the occasional sprinkler and maybe a hose pipe. All those technical questions you asked – the answer is no idea.
    thats a great idea about drilling a hole in the pipe.

    konabunny
    Free Member

    You don’t have a playpark next door you could hook it up to, do you?

    http://news.bbc.co.uk/1/hi/world/africa/4461265.stm

    ampthill
    Full Member

    I’m sure you know this but….

    The pump has to push the water from the bottom. You can’t suck water up this far

    My gut feeling is that a solar set up that can do this will be pricey

    shermer75
    Free Member

    I’ve never understood why capillary action can’t be used to get water out of a well

    Davesport
    Full Member

    A few things spring to mind. If you’re using a solar panel to charge the battery, you’ll need a solar charge controller. The panel doesn’t supply the correct voltage to connect straight to the battery. 2nd thing, the pump doesn’t state how much current it draws. This will obviously go up the bigger the head it’s got to pump so make sure you buy a big enough battery to run the pump for the time required. It’s going to pumping about 2 Bar to get the water to the surface so not too heavily loaded. Lastly, the pump supplies 6 Lpm on a good day. Is this enough to run your sprinkler or hose ? You might be better running the down-hole pump to feed an above ground header tank and taking your sprinkler & hose feed from there.

    D.

    ghostlymachine
    Free Member

    Do you need a licence to extract water where you are?

    I know we need a one off licence to change or install extraction systems.

    br
    Free Member

    Just a thought, but it might be easier to just automate the winder, and then have a simple header tank and immersed pump at ground level for the sprinkler.

    makecoldplayhistory
    Free Member

    “I just shot a laser measurer down it”

    I need to buy myself a laser measurer so I can use this sentence.

    How many dimensions can I tell my wife before she hides it?

    I have nothing useful to add.

    yorkycsl
    Free Member

    I’d think it has to be a positive displacement pump to over come the head pressure, sounds as case of maybe having to spend a few quid to get something decent that will last & be both reliable & cost effective.

    iolo
    Free Member

    Could you provide a lot ni to such a pump? As you might guess, I don’t really know what I’m doing.

    iolo
    Free Member

    That should say link. Bloody autocorrect.

    andyl
    Free Member

    What about using a pump to trigger a syphon action into a water butt and then use a second pump from the waterbutt for your watering? You might be able to use a submerged dirty water pump in the well or if you seal the water butt properly you could possibly use a piston air compressor as a vacuum pump to evacuate the water butt and draw up the water and then it should start to syphon

    Davesport
    Full Member

    The pump in the OP’s link is positive displacement. Just not a very big one. Anything powered from a battery and solar panel this size isn’t going to deliver much. 60 feet of head plus say at least a bar of pressure for delivery, 12V minus the voltage drop through the wiring and getting much flow is going to be difficult.

    Something like the pump in the link will do everything required at not much more than the cost of a 12V Pump, Battery, Solar panel & charge controller.

    Submersible Pump

    ampthill
    Full Member

    andyl

    Firstly

    Surely you can only syphon to water butt in hole more than 20m deep?

    Secondly re reducing the pressure in the barel. You can only raise water 10m buy reducing the pressure above it.

    iolo
    Free Member

    Ok, I measured the depth of water using the most technological method ever.
    Stone tied to a strong. Dropped in till it stopped. Pulled out the string and measurer the wet bit. It’s 2 meters deep and have 21.7 meters total depth from the top of ring to the base of the well.
    The well shaft is 900 mm internal diameter.

    ghostlymachine
    Free Member

    Dunno how much use this is going to be, but the wire going down our borehole is a frikking beast. The pump pulls a massive current on start up. It is pumping about 130 metres (but the pump is under 90+ metres of water. Nearer 110 during the winter.)

    I really don’t think solar and a battery is going to cut it though. Maybe a cable to an outside socket for the times you plan to run it would be better.

    andyl
    Free Member

    .ampthill – Member
    andyl
    Firstly
    Surely you can only syphon to water butt in hole more than 20m deep?
    Secondly re reducing the pressure in the barel. You can only raise water 10m buy reducing the pressure above it.

    It appears the limit is 10m due to vapour pressure but someone has done 15m by degassisng but didn’t bother to read the paper.

    What about a 2 stage by lowering a plastic barrel/bucket/trug into the well with a pump in and a pump down in the well. Use pumps with auto shut off. Bit messy but would halve the lift needed.

    thisisnotaspoon
    Free Member

    It appears the limit is 10m due to vapour pressure but someone has done 15m by degassisng but didn’t bother to read the paper.

    10m of water is a 0 absolute pressure, perfect vacuum, you can’t ‘pull’ 15m of water, there isn’t another 5 to pull it with, it just sits there in the pipe.

    papamountain
    Free Member

    Forget solar, that’s a massive head. Just get a reasonably powerful sump pump, throw it in and just plug it in when you need it. Most have float valves in case water level drops too low and will shut it off. Most will state what head they will pump to for a certain flow rate.

    andyl
    Free Member

    Not suggesting the OP does this but paper on >10m syphon:
    http://www.nature.com/articles/srep16790

    andyl
    Free Member

    As for the power it depends on how much flow you need. Getting a hose pipe type flow is realistically out using anything low cost but you could trickle pump to a water butt using solar at a low flow rate if you can find the right pump. Then use a high flow pump at the water butt. Tbh though it is probably a lot easier to just use a waterbutt fed from guttering.

    yorkycsl
    Free Member

    Anything battery or solar is very unlikely to do the job, you have no positive suction head pressure to speak of more NPSH and aldyl you sound to be on the right track with vapour pressure, if the pump cavitates which it likely will if a tiny centrifugal it’ll be knackerd in no time, look up pump wear ring / impeller cavitation damage for more info, we battle constantly with cavitation issues at work though in part due to blocked suction strainers & sand issues.

    ampthill
    Full Member

    andyl

    I’d not really though of syphons and the 10m limit. But the syphon doesn’t raise water. They are saying that you can carry water over a 15m barrier if its degassed

    The 10m limit is absolute for drawing water up with a vacuum as its being pushed up by the atmosphere

    yorkycsl
    Free Member

    ampthill

    To degass the water, I’m assuming you mean either Oxygen scavenger chemicals or through a Deairation tower under vacuum which is all mega costly & as you rightly say anything over 10m creates cavitation & your back to the drawing board & what ever pump is used will have to be self priming.

    andyl
    Free Member
    one_happy_hippy
    Free Member

    Dunno how much use this is going to be, but the wire going down our borehole is a frikking beast. The pump pulls a massive current on start up. It is pumping about 130 metres (but the pump is under 90+ metres of water. Nearer 110 during the winter.)

    I really don’t think solar and a battery is going to cut it though. Maybe a cable to an outside socket for the times you plan to run it would be better.

    This will be your major issue if you want to run it from solar.

    The 1.4kVa Pump we were using wouldn’t start on anything less than a 5kVa genset and even that was a push as the initial draw to start the pump can be 500% of that of the running draw.

    Depending on the pump you might get away with a soft starter but I suspect it’ll require mains to start it and then the solar can run it.

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