looking for pump speed control ideas

[cardamon]

Hi all.

The water level in my well can vary between 13 and 24 feet below the utilization point.  This has made finding a affordable pump problematic since there is a bit too much head for a surface pump and spending $600 on a submersible that is designed to lift a few hundred feet when I only need 20, is a bummer.  I did find a 12v sump pump that can do 23 feet of head and costs around $170, so I might try this one out.    Anyway, because my water line may not be below frost line, and my place might freeze if I go away for a few days in the winter, I thought I would set up the system so that when I want water, I just turn the pump on (no pressure tank or reservior).  However a way to vary the flow would be nice since the water level is so dynamic and the flow rate of this type of pump varies a lot with small changes of head.  Does anyone know of a pump controller that would work, i.e a variable voltage dc-dc converter that can handle 16 amps?  I am familiar with the constant voltage pump drivers that keep a fixed output regardless of battery state of charge, but I dont think that really helps me unless someone makes one with variable output? One hair brained idea I had was to instead use a 120v pump run off an el cheapo inverter and control the pump with a fan speed control/frac hp motor control - but with all that inefficiency I would probably be better off just restricting the flow of the 12v and let the pump draw full amps when it runs?  Any ideas greatly appreciated.

[RUFUS]

Just a thought

Have you considered an air lift pump

you would have to rethink your whole

system but they seem to work pretty well

no pun intended

                            Rufus

[cardamon]

Rufus,

I had not considered an air lift.  As I understand it, that is a similar concept as a "convertible", or two line jet pump?

[wpowokal]

Here is a link to a suitable kit, and they do post world wide..

http://secure.oatleyelectronics.com//product_info.php?cPath=94&products_id=206&osCsid=1bfdde
ecc2378853bbb259d96d4b8347

I would not use a sump pump, they are high (relative) flow low head. Do you have mains power or just the 12v? Your details are a bit sketchy, the greater detail you can post the better the advice you may receive.

A small submersable is the best off DC or mains, ask yourself how long do you expect this pump to last. Submersables here are priced relative to the number of pump stages rather than power rating, in the small domestic market.

Motors will draw an amount of power relative to there load (over and above that required to rotate them unloaded)

regards allan down under

[cardamon]

I do not have mains power - just a 12v battery system.  The problem is there are very few 12v submersibles that are a good match for my depth requirements - I dont want to pay $600 for a pump which is way overkill for my depth and usage (20 feet head, non pressurized, 10 gal/day).  The 12v sump pump I found seems to be a good match.  At 0 head it pushes 1500 GPH, but at the depth I have it will be a lot less and about right for direct usage.  Would this type of pump be less efficient?  FLA is about 16, but i dont know if that is locked rotor or for typical use.  Oh thanks for the link, that looks like about what I need.

[RUFUS]

Same deal  pretty simple  an air line

and a larger discharg pipe to the surface

check this bunch out AIRLIFTTECH.COM

they have a pretty cool wind turbine

powered air compressor/lift pump set up

but still it may take a bit of rethinking

as far as the whole system goes

                                 Rufus

[wpowokal]

http://www.windandsun.co.uk/pumps-fountains_lowvoltage.htm

[scottsAI]

Hello cardamon,

12v RV pumps work and are cheap, link is expensive, top of the line:

http://cgi.ebay.com/ebaymotors/SHURFLO-SMART-EXTREME-SERIES-5-7-PGM-RV-WATER-PUMP_W0QQcmdZViewItemQQ
categoryZ50070QQihZ009QQitemZ190161951217QQrdZ1QQsspagenameZWDVW

They can draw 3 to 12 feet and output 2-5gpm depending on the pump at 30-40psi.

I use one for backup to main pump. Testing worked great.

You many have to lower. (assuming it fits) Do not put in water.

I picked up couple for less than $50 ea. With shipping.

Have fun,

Scott.

[cardamon]

Thanks for the links guys, I'll look into some of these options.  With any luck the water will be flowing soon!