Fw: Need a Deep Well Pump Solution [RE-wrenches]

[Allan Sindelar]

Wrenches,
Many thanks to those who responded to the deep-well pump inquiry that I
posted two weeks ago (the original request for info is at the bottom of this
post). Ultimately, it appears that we have found three possible choices, and
I have presented these to the client without encouraging any one of them
strongly over the others. I'd like to outline the pros and cons of the three
options, to once again encourage feedback from Those Who Know More Than I Do
About Such Things.

Option 1: Grundfos SQ-Flex, set at 350-390', running on 120VAC from inverter
(or less efficiently, from generator). Could also run on battery power, but
only if client is willing to risk trying a 24-48V step-up DC-DC converter to
meet minimum 30VDC.
Advantages: 1. Well-known major company, with $millions invested in
developing this pump. 2. Dry-run external sensor at pump, so good for weak
well. 3. Reasonable cost, around $1450 retail. 4. Uses existing power
system, without major mods.
Disadvantages: 1. New product, without long history of operation. 2. All
electronics are down-hole, so any failure will require pulling the pump. 3.
Not recommended to install by hand. 4. Requires 2 conductors plus dry run
sense plus ground, so means replacing existing pump cable and in-ground
conductors. 5. Least efficient in watthours/gallon pumped of the three,
although I lack numbers (if it was array-direct, I am quoted 267 gpd using
172W of PV).

Option 2: Dankoff ETApump, running 48V array-direct, using a relay setup of
DC-coil relays, with coils energized by the float
switch in the storage cistern, to switch a portion of the client's array to
48V and send it to the pump controller.
Advantages: 1. Local support through Dankoff. 2. Simple pump design. 3. All
electronics above ground. 4. Very efficient.
Disadvantages: 1. New product, without long history of operation. 2.
Requires 3 conductors plus dry run sense plus ground, so means replacing
existing pump cable and in-ground conductors. 3. Requires array and array
input rewiring, so considerable changeout labor involved. 4. Unsure whether
24V-coil relays work well on 40V VOC of 24V array supply; if not, must run
24V battery feed conductors back to relays to supply coil circuits. 5. At
400', no hand installation.

Option 3: Solamotor jack pump, running as straight 24V load with float
switch/relay control, possible timer also. Awaiting more info on this
option.
Advantages: 1. probably most efficient of all, but I have no numbers yet. 2.
Lightweight, flexible drop pipe and sucker rod means easy hand removal and
service of down-hole equipment. 3. No electronics to fail. 4. Proven
approach. 5. Simple DC load off batteries.
Disadvantages: 1. highest system cost at $4-7K retail for system. 2. Can't
use existing pitless adaptor, so it will require that a covered, buried pit
be dug and installed around the well, in order to locate pump jack where it
is protected from freezing.

Which option would you recommend, and why?
Thank you all again.

----- Original Message -----
Sent: Tuesday, May 14, 2002 5:56 PM
Subject: Need a Deep Well Pump Solution [RE-wrenches]


> Wrenches,
> Here's a tough one. If any of you have solved this, or can suggest a good
> option, please do so.
>
> We put in a system last year for a good client. 24V, PS2524 (our last),
850W
> PV, SB50, etc. The water system was a SunRise 5218 with SC1B battery
> converter and Booster Pump. The power system has worked well; the water
> system hasn't. The SunRise pump has failed three times, and neither we nor
> the customer want to continue using it.
>
> The well is 500' deep, with weak (1+ gpm) flow at 330-350'. The SunRise
was
> originally set at 300', which the client knew was our recommended limit
for
> the hand installation method. When the pump started drawing air, we
lowered
> it to 350', which worked, but means a crew of 3-4 to pull it out, plus 2
1/2
> hrs of RT travel time.
>
> Dankoff has fixed or replaced the pump already (it's still under
warranty).
> We looked at using the ETApump, and the client would like to, but the lift
limit
> at 24V (rather than 48V) is about 200-250', which won't cut it. We could
use a
> 24-48V step-up converter, but don't want to until it has a proven track
> record in this application. The client can't afford an array-direct PV
array
> to run the pump. A conversion to a 48V home system is likewise pretty
> expensive, as it would mean adding two more modules (10 now), dropping
from
> 12 L16s to 8 @ 48V, changing SB50 to SB3048, and various other changes.

> Who has a better idea?
>
> Allan at Positive Energy
>

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