Submersible pump powered by an inverter?

[Derodeo]

I have an off grid well location where I would like to use a (not yet purchased)1/2HP submersible pump to bring up water from a depth of about 40'. Flow rate is not very important, convenience and reliability of the submersible is. My 2000 watt gas generator won't be powerful enough for the (largely unknown) startup requirements of the submersible pump. Soon I will have a 2500 watt continuous (3000 watt for 5 minutes, 5000 watt surge) modified sine wave inverter powered by a battery bank charged by a wind generator. Could I expect this inverter to provide the startup power required by the pump?

If not, what are my options? 12V, solar?

[ghurd]

I would not expect the inverter to do it.  Chicago Electric / HF brand by chance?

Half horse = 0.5 x 746W = 373W.  Expect a surge of 10X 373W or 3730W.  Maybe more.  IMHO pumps need more.  My experience says don't confidently expect a 4000W surge inverter to reliably start something like that.

"Flow rate is not very important"  

So why a large pump?  40' is not so high.

"convenience and reliability... is"

"options? 12V, solar"  

Maybe a Dankoff pump of one model or another?  Pricy, but good.  Save some money on gas or batteries?  Could spend more on water storage tanks and a 2nd pump.

Stray thoughts,

G-

[Norm]

Why not just use wind  power directly to pump

the water?

                   ( :>) Norm.

[Derodeo]

Well quite simply, I don't know how. Right now I'm satisfied just getting the wind generator to produce sufficient electricity for my needs. Since it doesn't sound like my inverter idea will fly, I'll have to do a lot of reading here to get a grasp on other possibilities.

Is a 1/2HP submersible considered a "large pump" because I have been unable to find (locally) anything smaller in a 115v submersible. Right now I'm using a convertible jet pump powered by a gas generator which I hate with a passion (prime, prime, prime, pump shuts off when tank full but generator doesn't have the power to restart it, wait a while, repeat prime, sigh)

I'm going to do some research on 12V possibilities, even though they are pricy. For one thing a 12V pump should make a good dump load if I have it set to pump up water up from the well and dump it back down. I guess another option would be a storage tank that gets filled maybe once a week and a second pump to pump from the tank. If I went that route could I maybe use a basic 12V RV type on-demand pump?

Thanks for your ideas.

[gizmo]

Sounds like the perfect job for an old farm windmill. Windmill pumps water into a holding tank, reliable and will last forever with very little maintenance. Down under the old Souther Cross or Comet windmills are popular, I recently picked up a old Southern Cross for $1200, think they are about $6000 or more brand new. The old farmers say they prefer the old mills over the new solar pumps, the solar pumps only last a few years, but after 50 years a Southern Cross is just run in! They push the solar pumps these days due to public liability insurance, its not very far to fall from a solar panel on a 6 foot stick compared to a 35 foot windmill tower.

My southern cross now pumps water from my rain water tank to a header tank 30 foot up the hill, I did have a 12v FloJet pump to do this but the brushes wore out after a few months!

Glenn

[nothing to lose]

Why did you have to prime so much? Sounds like something not set up correct to me.

First I'd make sure the inlet to the source pipe has a good footvalve, oneway valve, so once water is sucked into pipe it stays there, does not run back out when pump stops. Also make sure no leaks!

Second I would run the source pipe higher than the pump then down to the pump, the oulet pipe run up from the pump. With the pump in the low spot you should have a small U shape. I make my U shape about 2-3' tall.

Once primed if no leaks it should hold it's prime. Even when the inlet goes dry the U shape holds the prime to the pump normally.

 When pumping from barrels and tanks I do this allot, prime once and when barrel goes dry I shut off the pump move inlet hose to a full barrel and turn on pump. Never need to reprime.

 I used to haul water before I had a well put in, I did the same thing then, never had to prime even after runnning it dry, the upward oulet pipe holds water even when the inlet goes dry since there is no incomming water to push the last bit uphill.

If you get any air in the lines it should be at the top of the U shape, above water in the pipes, so pump is still primed.

I know that don't help with the submersible pump question, but if your only reall problem is priming you may not need the submersible unless for other reasons. Personaly I would preffer above ground pumps myself, but a 300' well I don't have much options.

 With an above ground pump I would look into a DC motor setup for my well. I have AC pumps I could mod with a used DC motor, but they won't pull the depth so can't do it here.

[Derodeo]

Yeah, I've got to have a leak somewhere but this is my second new foot valve and I couldn't detect any leaks when it was all above ground. Good idea regarding the U shape piping - however my pump instructions specifically call for all pipe to be downward sloping. Are you saying I should have both the source and outlet pipes a little higher than pump height or just the souce? I can try your idea though.

Main reason for changing the pump is that I'd love not to have to use my generator for pumping hours on end (irrigation purposes). Pricing out some 12V submersible pumps - they don't seem all that much more expensive than conventional AC submersibles since I don't (I think) need any type of controller to run from a 12V battery bank. Lots of them require 24V though - I could configure my battery bank to 24V easily enough but my inverter is 12V only. Is there any way around this?

Submersible pumps would have a big advantage to me in terms of protection from freezing. I do have some sand/silt in the well so that's a concern with many submersibles I understand. What to do, what to do...

[dwryoung]

I actually have this working for myself.  I have a Grundfos SQLFlex11 (11 GPM) $1400US in a well with static level of 21'.  Pump is at 40'.  I just purchased a Xantrex XPower 1750 $300US.  It starts and runs the pump fine.  Barely registers on the power meter after startup.  The beauty of the SQL Flex is it will take AC 120-240 V or DC 32 - 300 V.  I can shoot water 30' away with a 1-1/2" fire hose through 200' of hose.  Contact me if you want more details or pictures.

wm

[hydrosun]

I like the grundfos pumps also. But the direct AC models are much lower cost if you don't need the features to be able to run directly off of solar panels. Check Backwoodssolar.com for 1/2 HP 115 volt pumps.

Chris

[nothing to lose]

"Good idea regarding the U shape piping - however my pump instructions specifically call for all pipe to be downward sloping. Are you saying I should have both the source and outlet pipes a little higher than pump height or just the souce?"

I don't know why a pump would need downwards piping? That's just asking for an airbubble to be located right at the pump that way! There may be a reason for it? I don't know that much about pumps really but I know what's worked for me very well for various uses and pumps.

With the pipes going upwards on each side of the pump then the pump should always be full of water. Even if the source goes dry (like pumping from a tank) the outlet pipe stays mostly full while the pump tries to pump air. When the pump shuts off then that water in the pipe flows back into the pump as any air rises to the top. Depending on the pump, most will let the water seep back through, since water seeks it's own level then with the pump not running the water in the outlet pipe should seep back through into the inlet pipe. So if you have say a 2' rise on both pipes and pump dry, after shut down the water should flow back from the oulet pipe and both pipes be 1' full and the pump still be primed.

Many of the above ground pumps have a AC motor that is easily removed, the pump is basically a seperate unit. With such a pump you could install a DC motor various ways.

If you find a motor with the correct mounting and shaft size great and easy. If not, you could make up like a jack shaft of the correct size ( original motor shaft size)and use a sprocket and chain or belt and pulley. Drive the shaft with any motor you want, AC or DC.

You can get fairly cheap 1/2hp 24V dc PM brush type motors. You might be able to find 12V motors, or you could modify a car starter or 2 if you wanted. I would do 2 or 3 at once so I had spares on hand.

Depending on your water needs a 12V car starter would certainly pump water, it would need modded to remove heat for the longer run times, and also need to mod it for a drive system of belt or chain, unless you found a nice gear to match up with it.

Just a few thoughts and ideas.

If I had a shallow well I would be doing such things, but mine is 300'deep and I think the water is 100' down, so I have allot more problems than a 40' well has for pumping.

[scottsAI]

Hello Derodeo,

Your problem can be solved with money, I expect your trying to minimize it.

We need to know how much you will pay for that 1/2hp well pump.

Searching around you can find many DC well water pumps.

Shurflo 9300 Submersible Water Pump, looks the cheapest at $650.

Soft start well pumps for inverters, $1800.

Not good to run most motors on MOD SIN. Considering the motor is water cooled. Expect it to work.

Motors can have a soft start added reducing peak starting current.

Not normally used, not a problem with grid power.

My last 240vac 1/2hp well pump's label stated Locked rotor current 14.9a. Funny, the house had a 15a breaker on it, tripped once, next day the motor fried. Starting controller cap died.

Not easy, Not hard to add series resistance to limit starting current. We covered this in a post recently.

Have fun,

Scott.

[dwryoung]

With my setup, the modified sine wave and SQL Flex Pump, I am wondering if the modified sine wave really matters?  Wouldn't the pump itself rectify the AC to DC since either current works with this pump?  Would this not turn the modified sine wave into pulsating DC which is what is used in a lot of applications as a speed control.  I am basically using the inverter here to step up the voltage so I can use smaller wire.   Is this the correct way to look at this?

[scottsAI]

Hello dwryoung,

Like you said earlier 30vdc and up 90vac and up.

So the MOD SIN for you doesn't mater. Like you said thiner wire.

Might be cheaper to use thicker wire and directly power it with 48vDC!

Inverter is just one more thing to fail. Assuming you have 48V!

Yes, I am sure the SQLFlex11 is converting input to DC and conditioning it as needed for the conditions. Very unusual well pump. Then again for $1400 it had better be something special!

Since Derodeo said flow did not mater then the Shurflo 9300 is half the cost!-)

I am real cheap, I might consider using the RV pump and lower it into well, just above the water, I got a 4.7gpm for $50 on ebay, delivers 40psi at 2.5gpm with 6 foot draw. Use it as back up pump or when mains fail. Not had to use it since I got the parts. RV pumps are for intermittent use.

Have fun,

Scott.

[Derodeo]

Thanks for the many good ideas. I've been looking most closely at the Grundfos SQ series of submersible pumps, specifically the 10SQ05A-160 model (about $500 from the US or $1200 from Canada!). Again, the submersible AC design is more appealing to me due to realiability and protection from freezing. This pump is supposed to be able to run from a cheap 1700 watt inverter (modified sine wave I presume) so from that viewpoint it sounds pretty ideal. I can't see the MSW having much of an impact here because, although personally I have an inverter style generator, I know of several who use large cheap generators to run their water pumps.

One complication; my well is not the modern narrow 4" pipe design. It's actually about 30" wide (wooden plank shoring all the way down - must have been a life-altering experience to build it). I'm told that submersibles need a narrow shaft for the circulating water to aid in cooling. Grundfos sells a flow sleeve for these pumps that encases the pump and either helps cooling or helps protect from sendiment (conflicting information here). Incidently in previous years when grid power was available, a conventional submersible pump was used in this well for a long time without problems so perhaps a flow sleeve is not really necessary.

[Tess]

we just installed a 750w submergeble pump at around 120 foot and it worked fine with a 2kw inverter (peak 4kw)powered from panels and turbine. is only at esting stage but we have enough power to raise the water tank another 15 foot.