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Pumping Head Question

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  • burrows206
    Hi Ray Boy, This has been covered before but in past posts but basically a centrafugal pond pump is your best answer if near a mains supply, if out in the
    Message 1 of 2 , Jan 31 1:22 AM
      Hi Ray Boy,
      This has been covered before but in past posts but basically a
      centrafugal pond pump is your best answer if near a mains supply, if
      out in the sticks, utilize a tree or rock overhang.
      As a recap I've high lighted and copied a few of relevant posts
      that should go a good way to answering some of your questions

      --- In Distillers@yahoogroups.com, "burrows206" <geoff@...> wrote:

      > I'm a retired plumber and what you say is perfectly true.

      One of those factors (THE main one). Is
      > the height of the pumped head and that can be changed by raising
      the
      > volume of available cooling water and placing it higher than your
      > column cooling coil. (In the rafters, next floor is good) You're in
      > effect not pumping water that's below head height, in this
      > configuration. Strictly speaking you're only circulating it or just
      > moving it along at "x" speed in the pipe line.
      > And circulating is easier than pumping.
      >
      > Geoff
      >


      Geoff, there's one tiny thing niggling me on this. Yes I see what
      you're saying about 'circulating', but if you are returning the water
      to the holding tank on the next floor, aren't you again dealing
      with 'pump head' capability? Aren't you 'lifting' or 'pushing' the
      water to a higher level? Isn't that what 'head' is all about? I'm
      no
      plumber, but I'm keen to know. It could prove useful in formulating
      charts. Can you shed some light on this?


      Slainte!
      Regards Harry

      My Reply post to Harry,

      Hi Harry,
      As you know water will always find its own level, back at the
      Head from where it set out from. In our case this is where the pipe
      goes over the side of the tank. Now a submersible centrifugal pump
      in the holding tank will pump water 6" or 7" up over the side of the
      tank. Gravity will also help to do its thing on the flow pipe
      (positive) side of the pump and the water will fall to the condenser
      and go through it.
      The weight of this continuous falling water will push the water
      back up on the return pipe side of the condenser to the exact spot
      (height) where the water started the down-ward trip (i.e. the edge
      of your holding tank ) From then on your pump will only be pumping
      a head of 6" or7" over your tank edge.
      Alternatively if you pump water from your submersible
      centrifugal pump out through the side of your holding tank, about 2"
      up from the bottom ( keeps your outlet away from pumping any
      possible crude that might fall into the tank).
      The idea of doing it this way is the head of water is above
      the flow pipe outlet and the pump inlet area which let's not forget
      is inside the holding tank. With the pump
      switched off, the water will flow freely through the centrifugal
      pump go down through the condenser and back up to the inlet at about
      the 2" mark from the base (or where ever you put the inlet back into
      the holding tank) but this must be below the water head (level) of
      your
      holding tank. Now that your system is self primed all you will be
      doing with the centrifugal pump is circulating the water.
      Down pressure will equal the up pressure in both flow and return
      pipes
      The pipe bore (volume) and wall resistance (flow dynamics) now
      becomes an issue and there are plenty of charts/ tables out there on
      the internet that deal with all that scientific stuff.

      That's about as well as I can explain it Harry.

      Geoff


      Harry wrote

      Thanks Geoff. Well explained too. Yes , I should have realised
      about
      water finding it's own level. I haven't found any charts yet (not
      looking too hard, got sidetracked). But the sidetrack actually gave
      me exactly what I was looking for...Bernoulli's Equation and, more
      importantly, Poiseuille's Equation.
      http://tinyurl.com/s5v64
      Hoo boy! Now for a bit of figuring. :-))

      Slainte!
      regards Harry


      Hope this helps

      Geoff
    • Ray boy
      burrows206,Very Helpfull Info there I think I just got a lesson in hydronics. Apprecaite youre time in posting that ... burrows206
      Message 2 of 2 , Jan 31 5:19 AM
        burrows206,Very Helpfull Info there I think I just got a lesson in hydronics. Apprecaite youre time in posting that ...

        burrows206 <geoff@...> wrote:
        Hi Ray Boy,
        This has been covered before but in past posts but basically a
        centrafugal pond pump is your best answer if near a mains supply, if
        out in the sticks, utilize a tree or rock overhang.
        As a recap I've high lighted and copied a few of relevant posts
        that should go a good way to answering some of your questions

        --- In Distillers@yahoogro ups.com, "burrows206" <geoff@...> wrote:

        > I'm a retired plumber and what you say is perfectly true.

        One of those factors (THE main one). Is
        > the height of the pumped head and that can be changed by raising
        the
        > volume of available cooling water and placing it higher than your
        > column cooling coil. (In the rafters, next floor is good) You're in
        > effect not pumping water that's below head height, in this
        > configuration. Strictly speaking you're only circulating it or just
        > moving it along at "x" speed in the pipe line.
        > And circulating is easier than pumping.
        >
        > Geoff
        >

        Geoff, there's one tiny thing niggling me on this. Yes I see what
        you're saying about 'circulating' , but if you are returning the water
        to the holding tank on the next floor, aren't you again dealing
        with 'pump head' capability? Aren't you 'lifting' or 'pushing' the
        water to a higher level? Isn't that what 'head' is all about? I'm
        no
        plumber, but I'm keen to know. It could prove useful in formulating
        charts. Can you shed some light on this?

        Slainte!
        Regards Harry

        My Reply post to Harry,

        Hi Harry,
        As you know water will always find its own level, back at the
        Head from where it set out from. In our case this is where the pipe
        goes over the side of the tank. Now a submersible centrifugal pump
        in the holding tank will pump water 6" or 7" up over the side of the
        tank. Gravity will also help to do its thing on the flow pipe
        (positive) side of the pump and the water will fall to the condenser
        and go through it.
        The weight of this continuous falling water will push the water
        back up on the return pipe side of the condenser to the exact spot
        (height) where the water started the down-ward trip (i.e. the edge
        of your holding tank ) From then on your pump will only be pumping
        a head of 6" or7" over your tank edge.
        Alternatively if you pump water from your submersible
        centrifugal pump out through the side of your holding tank, about 2"
        up from the bottom ( keeps your outlet away from pumping any
        possible crude that might fall into the tank).
        The idea of doing it this way is the head of water is above
        the flow pipe outlet and the pump inlet area which let's not forget
        is inside the holding tank. With the pump
        switched off, the water will flow freely through the centrifugal
        pump go down through the condenser and back up to the inlet at about
        the 2" mark from the base (or where ever you put the inlet back into
        the holding tank) but this must be below the water head (level) of
        your
        holding tank. Now that your system is self primed all you will be
        doing with the centrifugal pump is circulating the water.
        Down pressure will equal the up pressure in both flow and return
        pipes
        The pipe bore (volume) and wall resistance (flow dynamics) now
        becomes an issue and there are plenty of charts/ tables out there on
        the internet that deal with all that scientific stuff.

        That's about as well as I can explain it Harry.

        Geoff

        Harry wrote

        Thanks Geoff. Well explained too. Yes , I should have realised
        about
        water finding it's own level. I haven't found any charts yet (not
        looking too hard, got sidetracked) . But the sidetrack actually gave
        me exactly what I was looking for...Bernoulli' s Equation and, more
        importantly, Poiseuille's Equation.
        http://tinyurl. com/s5v64
        Hoo boy! Now for a bit of figuring. :-))

        Slainte!
        regards Harry


        Hope this helps

        Geoff



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