Should have mentioned....

There are some changes that should be made if you want to build a unit for yourself.

The focal plane should be the width of the cylinder (4") x 3.1416 + the diameter of the cylinder. In this case
it would be 16 5/8". That would make the parabolic chamber close to being a square instead of rectangle.

The unit should be positioned at an angle to the sun in
the summer. You may just accidentally set the unit on fire.

For all weather use the unit should be covered in fiberglas or
made of metal. Exterior grade plywood just isn't good enough.

-Rick

I'm sure I don't have to tell Rick, but for others who may read this should know, that safety precautions need to be taken when working with unregulated high temperatures and water. Essentially, rick built a bomb if not fitted with pressure relief valves. While they post 600F for temps, it's unlikely the heated fluid would achieve that. Never the less, water pressure increases exponentially with temperatures above the ambient atmospheric boiling point temperature. For example, a sealed vessel of water heated to 281F will have 50 PSI of pressure, but heat it just another 47F and the pressure doubles. 100F above 281F and the pressure quadruples!!! If you continue to heat it to 545F, the pressure would be 1000 PSI!!!

But the real danger comes with a rupture of the vessel containing the superheated water, as any pressure drop at a given temperature will cause the water to flash to steam, and steam expands 1680 times the volume of water. So pieces of your now rupturing vessel gets an extra push from the instantly expanding gas, and basically you have a water powered pipe bomb.

So, always be sure to have a pressure relief valve (sized safely below the vessel pressure limits) any time you consider heating water above the boiling point in a closed container.
~~~~~~~~~~~~~~
Side note: I once asked a steam locomotive engineer what pressure they operate their boilers at. When he told me 180 PSI, I was shocked to say the least. I can imagine that a catastrophic rupture in something that size would probably darn near take out a city block, and send train parts a mile from ground zero. Come to think of it, I believe I recall some WWII aerial gunsight footage of steam locos be shot, and doing just as I envision.

"That's why he's going to install it in his favorite neighbor lady's yard and run a long pipe.... :-)"

I'll get two! On for each neighbor!

Actually...Rod is right. I knew I had a bomb, but the engineer & I both came up with
about 400PSI ultimate strength. I may not reach 400 PSI, but it is certainly possible.
The unit is mounted out in the field about 50' away from me...MUCH TOO CLOSE!
Mounting it in the next county might be safer. I need to install a pressure regulator
on top, or maybe a simple pop-off valve. When I open the ball valve the burst of water
takes about 3-4 seconds to fly into the air and fall to the ground. This is at low temperatures!
I've seen videos of a BLEVE (Boiling Liquid Expanding Vapor Explosion) and they're
not pretty. People several blocks away are killed. Good thing my unit is small. I know
it takes a short exposure to the sun to reach comfortable shower temperatures. Set
and forget for several hours with all the reflectors in use could be catastrophic.
Thanks for the heads-up Rod, I'll get a valve...or you can read about my exploits in the
Darwin Awards. =8-O

Would like to build the big unit...eight reflectors at 13' long...maybe a parabolic chamber.
Better build a lot of safety features into that unit. Materials, money, and design are no
problem to building the next unit. The safety feature is that I don't have enough time to
dedicate to building the next unit. Too much mad scientist in me.
(That's "Fronkenschteen!" Gene Wilder)

-Rick

Already looked into it. The water heater generates a lot of power but slowly over
a period of time. Despite the large size (71 sq. ft.) of the reflectors I would only be
able to generate about 15 watts if the sun was always shining directly on the
reflectors. Works best for heating water & food. Would take ten stainless steel
cylinders filled with water to heat my storage shed for just one hour. On an average
winter day I might get three cylinders of hot water, but would need 250 cylinders to
keep the place up to temperature for 24 hours. Would also work for generating ice,
but the best I could expect is to keep my Coleman ice chest cool.

The numbers show that for the area of the reflectors I should generate close to 500
watts of power, but with occasional sunshine, friction losses, etc. the real numbers
are far from the theoretical numbers.

Too bad. It does sound exciting to have free energy.

-Rick