water pumps, DC vs. AC motor

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I pumped a bunch of water today, using 2 different pumps, one an AC
submersible slightly larger than Gig's, the other a small Bell & Gossett,
probably formerly used in a circulating water heating system, now powered
by a 1/4 HP 24VDC motor. I have some performance and power draw comparisons.

My solar power system is 24 volt. All currents are DC draw from the
battery (DC input to the inverter, in the case of the AC pump). My
inverter is a Trace SW4024, 120 V 4KW sine wave.

The AC submersible pumped 200 gal/hr, current draw from the battery was 13
Amps DC.

The DC pump moved 225 gal/hr, drew 10 A from the battery. (67% of full load
current)

Static head was about 4 ft., friction head was 150 ft. of 5/8" garden hose.

For comparison, I'll use an arbitrary index of gallons per hour per ampere.

Submersible: 200 GPH / 13 A = 15.4

DC: 225 GPH / 10 A = 22.5

DC / Sub.: 22.5 / 15.4 = 1.46 (on a basis of current drawn, the DC is 46%
more effective.)

I had expected a greater difference, and may get more with further
tinkering. The DC pump seems awfully tight, shafts may be mis-aligned.

For what it may be worth.


Tom Willmon
Mountainair, (mid) New Mexico, USA

PIT BULLDOG FOR SALE: Eats anything. Loves children.

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[Pete C]

My solar power system is 24 volt. All currents are DC draw from the
battery (DC input to the inverter, in the case of the AC pump). My
inverter is a Trace SW4024, 120 V 4KW sine wave.

The AC submersible pumped 200 gal/hr, current draw from the battery was 13
Amps DC.

The DC pump moved 225 gal/hr, drew 10 A from the battery. (67% of full load
current)
The DC pump moved 225 gal/hr, drew 10 A from the battery. (67% of full load
current)

Static head was about 4 ft., friction head was 150 ft. of 5/8" garden hose.

Hi,

A diaphram pump like a Shurflo or Flojet are quite good in this
application and would draw about 2.5A at 24v:

http://www.flojet.com/prodInfoApp/s...ET&catalogId=RV&categoryId=FRMPU&typeId=FRQSP

cheers,
Pete.

 

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Newsgroups: alt.energy.homepower
... ...
A diaphram pump like a Shurflo or Flojet are quite good in this
application and would draw about 2.5A at 24v:

That's true, Pete, though its delivery would be roughly 1/2 as much, and
I've been looking for higher volume than my various Sureflo's give.
However, the Sureflo's Arbitrary Index Rating (R) is 48, >twice as good.
Wonder about 2 running in parallel...

Since they are mostly associated with RV's, I tend to not take them that
seriously. However, a neighbor uses a Sureflo for all house water for a
family of 5, without any pressure tank to reduce its cycling. I'll ask
about reliability next time I see them. Mine have been quite reliable.

My point in posting this data was to give some rough idea of what the
efficiency difference between AC induction-motor and DC powered pumps might
be. I hadn't seen any data previously.


Tom Willmon
Mountainair, (mid) New Mexico, USA

If it's Tourist Season, why can't we shoot 'em ???

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[Pete C]

That's true, Pete, though its delivery would be roughly 1/2 as much, and
I've been looking for higher volume than my various Sureflo's give.
However, the Sureflo's Arbitrary Index Rating (R) is 48, >twice as good.
Wonder about 2 running in parallel...

Hi,

The Flojet pump in the above link is rated at 4.5gpm/17lpm which is
pretty similar to the ones you quoted.

Since they are mostly associated with RV's, I tend to not take them that
seriously. However, a neighbor uses a Sureflo for all house water for a
family of 5, without any pressure tank to reduce its cycling. I'll ask
about reliability next time I see them. Mine have been quite reliable.

I've had used a Sureflo for my water supply for about 12 years, and
it's been pretty reliable. I've also fitted a Flojet for a neighbour
and was quite impressed with it, the design seems more modern.

The only problem I've come across with these pumps is that the
microswitch in the pressure switch can wear out, but if the pump motor
is switched via an auto relay this won't be an issue.

My point in posting this data was to give some rough idea of what the
efficiency difference between AC induction-motor and DC powered pumps might
be. I hadn't seen any data previously.

True, I thought it might be of some use to people who might be looking
for a pump to use off grid.

cheers,
Pete.

 

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Newsgroups: alt.energy.homepower ...
The only problem I've come across with these pumps is that the
microswitch in the pressure switch can wear out, but if the pump
motor is switched via an auto relay this won't be an issue.

I wire a diode, back-polarized (lead with bar on it connected to positive),
across the motor leads to short out the inductive kick-back when the switch
opens. No failures yet in 4 years use household (trailerhold?) use.
[Living in 5th wheel while messing about, building.]


Tom Willmon
Mountainair, (mid) New Mexico, USA

"Remember: It only seems kinky the first time!"

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[Scott Willing]

That's funny.. I thought flowers came in bunches.. ?
how does one "have" a "bunch" of water ? .. did you mean to say a large
volume
of water ?

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have been filled.

We'll keep your resumé on file for future consideration.

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[James Baber]

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[Steve Spence]

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I keep cats. They don't even mess with my canary, let alone the chickens.

Newsgroups: alt.energy.homepower
My malamute loves my kids, the kids don't always appreciate a 120lb
dog jumping all over them.

My neighbor had a malamute named Wolf, loveliest dog I ever knew. He used to
come visit, sometimes sleep outside my bedroom window (could hear him
breathe), hide in my garage if there was a thunderstorm. I miss him.
Should I ditch that smartass tag line?

Tom
See America - get lost on a rallye.

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