Making an Undershoot Water Wheel

Undershot Water WheelThis is a nicely done undershot water wheel project that blends in well with its setting. Much of the project was done with parts recycled from various sources. Full details on how to construct the wheel (pdf 3.5 MB) Excel Spreadsheet model to help with design (Excel xls 27 KB) Thank you Allan for submitting this!!

Update from Allan -- April 18, 2008 .... Some Follow-up qustions on the water wheel -- 2/15/07 ...

"Water Wheel Engineering", a paper by Ron Shannon with some gooddesign information on undershoot water wheels.

Some pictures of the water wheel:Note: A couple of these pictures do not appear in the "Full Details" write up above.

The wheel in operation

H o m e G e ttin g S ta r te d P ro je cts R e fe re n ce s H a lf P ro g ra m E x p e r im e n ta l S ite M a p

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Making an Undershoot Water Wheel 2/2/2014

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View from inflow side of wheel.

Tape drive motor used as generator, and cable spool ends that form the sides ofthe wheel.



The wheel buckets cut from PVC pipe.

Shaft, bearings and primary gear. A larger gear ratio than is shown will probably be required for good performance -- download thepdf file listed above for details.



Generator and gearing.



Looks like its been there for a hundred years. Some Follow-Up Questions:These are the answers to some email questions on the water wheel:

1) How does the generator hook up to the power source? Single battery or multiple?

As several of the photos show, I use an isolation diode (30 Ampere) to prevent the battery bank (Ten 220 AH T-105batteries wired in series/parallel for 12 volts @ 1100 AH) from back feeding the generator. The hookup is through a 30ampere Square-D QO breaker right onto the battery buss of my solar system. There is no need to use a controller sincethe power output from the generator could not overcharge the battery bank.



2) Where can I get a generator as shown? What is the generator connected to in the picture with the generator mounted in the gearbox?

There is a pretty good discussion of this particular generator/motor athttp://www.otherpower.com/otherpower_experiments_tapedrivemotors.html along with possible locations where one couldpurchase one. Another option would be to use a permanent magnet automotive alternator fromhttp://www.hydrogenappliances.com/powerpmas.html though I've not tested performance with one, it would be my choicewith a larger water wheel. As to question 2b, see my answer to question 1.

3) Do you have to regulate/control the charging of the battery somehow? With what?

See answer to question 1.

4) It seems like the water is entering at midpoint of the wheel. Would more power be produced if water entered at the top - a true overshot wheel?

As Ron Shannon's Water Wheel Engineering presentation at http://ipc6.permaculturewest.org/ch08/shannon/index.htmlindicates, the efficiencies of an overshot and undershot wheel are very similar. The selection criteria I used was a matter ofavailable head at my alternate site. The original site and intent was to incorporate the wheel in an overshot configurationbut my wife had other plans. I had taken photos and written a bit of a detailed story as to how the current location wasselected after my original location (a four foot waterfall) was firmly rejected just prior to installation for aesthetic reasons... Ilater opted against submitting it since it offered nothing of value to the design other than an example of its flexibility.

5) Author did not say what he was powering from this wheel/generator. Any idea?

I utilize the power generated from this wheel to subsidize the output from the two 500 Watt solar panel racks as it wasavailable and otherwise a wasted resource. New England has had no scarcity of rainfall these past few years at theexpense of diminished sunshine. The composite system powers communications equipment, three freezers, propanefurnace/hot water, well pump and all electrical requirements of my barn thereby reducing my utility bill by 50%.

I'm pleased to report that the waterwheel has performed very well up until the stream froze solid. I'll let you know how it does after thespring thaw and about 2 million gallons per day attempts to get past it during April/May. Allan Thanks to Allan for providing these answers!

Update from Allan on April 18, 2008:

"I tightened up the tolerances around the sluiceway to give merely a 1/4 inch clearance to the water and this resulted inalmost a 30% increase in velocity and torque. I'm researching (in earnest) a more efficient generator to boost the outputcloser to the theoretical value." Allan

11/27/06Updated 2/15/07, April 18, 2008

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Undershot Water WheelSome Follow-Up Questions:Update from Allan on April 18, 2008:

Making an Undershoot Water Wheel

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