Allotment Gardening Advice Help Chat

Smallhold Farming and Rural Living => Property, Buildings, Equipment and Alternative Energy => Topic started by: grendel on November 24, 2010, 20:04

Title: solar water pump
Post by: grendel on November 24, 2010, 20:04
ok on my plot I have the site stopcock, it obviously has a very slight leak as the tube it is down is full of water and drips occasionally. now the nearest stand pipe is easily 100 yards away, so I had a thought, what if I could catch the drips and redirect them to a waterbutt.
my thoughts were to arrange a small catch reservoir, and then have some sort of solar pump to pump the drips up a few feet from ground level up to the waterbutt, all I needed was a pump that would deliver just a few litres a day. I had some thoughts and have come to the conclusion that an archimedes screw made from a coiled piece of hosepipe round a central pole angled about 45 degrees, powered so it slowly turns through the day, raising water up to the height of the waterbutt. something using the principle in the image below.
http://www.columbia.edu/cu/physics/demo-images/2-Fluid%20Mechanics/2B60-1_1_archimedes_screw.jpg
the power might well be a 12v solar cell, driving an old telescope drive motor (these are geared down to about 1 rpm, and I have spares from my astronomy hobby). if neccesary I can add a rechargeable battery into the mix, but a bit of experimentation is in order at the moment, I wont be able to put it on the plot until next spring and the possibility of freezing has passed.
Grendel
Title: Re: solar water pump
Post by: John on November 26, 2010, 00:11
Would one of the solar pumps sold for garden ponds not be an easier solution? - speaking as someone with no engineering skills. I suppose you'd have to consider it running dry though.
Title: Re: solar water pump
Post by: 8doubles on November 26, 2010, 08:24
I think that you will need a lot more than one RPM to get a decent head of water , too slow and gravity will win.As John said running dry will be a problem without a float switch.

Probably easier but less fun to fix the leak and use tinkering time for an auto irrigation system for the runner beans. :)
Title: Re: solar water pump
Post by: grendel on November 26, 2010, 17:11
It would be easier but for two things, the nearest standpipe is about 100m and the leak is not mine to fix, at best its the councils, at worst the water company - after  all they supply the water to that point.
the archimedes screw in a hose works because there are little pockets of water that gravity stops the water coming out of - so speed is not an issue. as for running dry- that too is a good part of the system as it will run as well dry as it will wet.
Grendel
Title: Re: solar water pump
Post by: 8doubles on November 26, 2010, 17:55
I think i`m with you now, the screw takes a gulp of water then air so does not siphon back. :)
Title: Re: solar water pump
Post by: Goldfinger on November 26, 2010, 18:05

I'd love to know how far you would need to dig or drill to make a well.

My Grandad's old allotment used to have a big brick lined one.
Title: Re: solar water pump
Post by: ex-cavator on November 26, 2010, 23:55
I think the theory is fine, but unless the leak is significantly more than an occasional drip, you'll never fill the warter butt  :)
Title: Re: solar water pump
Post by: grendel on November 27, 2010, 13:29
its quite a steady drip really.
Grendel
Title: Re: solar water pump
Post by: Caltrad on November 06, 2011, 21:49
Thoughts...

Some sort of reservoir that catches the drips...a "float switch/timer" which actuates a 12v pump (Car washer pump?) whenever there's a decent amount of water in the reservoir. All powered from a 12v battery which is charged by the solar panel.

Logic is that while the reservoir is filling the battery is being charged.

You'd need to experiment to find the optimum "solar-panel-to-reservoir-capacity" ratio.
Title: Re: solar water pump
Post by: Caltrad on November 06, 2011, 21:51
Thought #2: You might want to keep a close eye on the drip, it migh burst and flood your plot!