water pumps, DC vs. AC motor

Question:

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. Net-Tamer V 1.12.0 – Registered

Response:

>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/servlet/DisplayItemDetail?itemId=R4… cheers, Pete.

Response:

> I pumped a bunch of water today, using 2 different pumps, one an AC

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 ? – Hide quoted text — Show quoted text -> 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. > Net-Tamer V 1.12.0 – Registered

Response:

   >Newsgroups: alt.energy.homepower  …    >>The AC submersible pumped 200 gal/hr, current draw from the    >>battery was 13 Amps DC.  Index 15.4.    >>The DC pump moved 225 gal/hr, drew 10 A from the battery. Index 22.5.  …    >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 ??? Net-Tamer V 1.12.0 – Registered

Response:

>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.

Response:

   >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!" Net-Tamer V 1.12.0 – Registered

Response:

>> I pumped a bunch of water today, using 2 different pumps, one an AC >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 ?

I’m sorry, all positions for official alt.energy.homepower pedants have been filled. We’ll keep your resum

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