Autotransformer to run Well Pump? - Page 3

 wrote:


He likely has deep water. Most domestic submersibles are sized for 5
gpm, and that flow rate usually requires 2hp beyond about 700' if open
discharge (pumping into storage) or about 500' if supplying 50psi on a
single-pump system. If it is deep, swapping it out for a more
efficient model could be a pretty expensive proposition.

Wayne

 

My well is 126' deep and I have an additional 440' of head to my storage
tank.  It pumps about 17 gpm at my house level and I'm expecting about 15
gpm on the top of my hill.

Is 126' deep?  I didn't think it was.

 

On Thu, 22 Mar 2007 17:52:28 -0800, "Ulysses"



Your well is relatively shallow, but many would consider the total
head deep. A conventional 2hp submersible at 500' total head can be
expected to deliver about 8 gpm into your tank. Most folks with your
well depth, but without the hill, do fine on 1/2 hp, and are shocked
to learn that in some parts of the country residential wells can be
1500' deep. A friend's well is 1300'. It has a 3hp, 460V 3 phase pump,
supplied by a 230 -> 460V transformer, a VFD, and a filter. The
equipment was necessary to reduce the cost of the wire, which is some
1800' total. That well and pump setup cost upwards of $30k.

You could replace your pump with a Grundfos SQ Flex or a Lorentz. Both
use an efficient helical rotor, and could deliver about 2 gpm to your
tank on say, 200W of PV. Price is nearly the same for each, about
$1500. The Grundfos can be powered by DC or AC, and the motor is the
same small diameter as the pump head. The Lorentz is DC only, and the
motor is larger but it still fits easily in a 4" casing. Either could
be set by hand at your depth. Buying a more efficient pump could pay
if it saves you having to expand your solar setup substantially beyond
what you'd otherwise need, or if you pump enough water that the
efficiency improvement becomes more of an advantage. For example, we
normally do well with a conventional 1/2 hp pump at our place. But
occasionally when we're watering cattle we're pumping five times the
water, which means as much as a couple extra kWhrs per day. When the
weather's hot, that's energy we'd rather put into AC. If it ever
becomes much of an issue then I'm going to replace the conventional
submersible with an SQ Flex, and run it on 120V AC.

Wayne

 



The good news is that my water is only down around 15' and at the end of a 7
year drought it was at about 27' so I would probably be OK placing a pump
down about 50'.  If I had to I could always put the water tank lower and use
a 12 volt pump for pressure but I like to keep things as simple as possible.
I have two 5000 tanks most of which is required by the fire department but
my main water supply right now is a single 55 gallon plastic drum up on the
hill with 1/2" poly tubing going to the house.  Surprisingly there is enough
water flow and pressure to take a decent shower but the trick is the shower
head: it's an RV type head with shut-off and the spray is adjustable to
"needle spray."  I just bought a 650 gallon tank which is going up about 25
feet higher and it's going to have 1 1/4" pipe so I'm expecting a
significant improvement.

My new neighbor down the road just got his well drilled and the last I heard
they were at 700'!  This is unheard of around here.  I guess he didn't call
the right well driller that everyone else uses.

As for the 8gpm at 500' of head I'm pumping to about that height now and
I've measured it at 17 gpm.  I must have a really good pump.  I'll have to
go look for the info on it and see what brank it is.  It was not cheap.

 On Fri, 23 Mar 2007 09:29:03 -0800, "Ulysses"



Something doesn't sound right. Even a 3hp should be more like 13 gpm
at 500'. Are you sure about your elevation measurements? You should
only count the depth to the water, plus the extra height to the tank.
That would make it 455' plus friction loss if I understand your setup
correctly. What kind of layout is your property that the storage tank
is 440' above the well? How long is the pipe run between the well and
the tank, and what size is the pipe?

Wayne