This is not hot water but hot air.
Here is something else you might want to consider. A solar panel to heat air. Thus no water to leak or freeze. I built this panel a year ago to experiment with heating air.
It starts out with a 4 x 8 foot piece of 1/8� thick masonite panel for the back then there is 1 �� of Styrofoam insulation covered with thin sheet metal painted black. Next is a 1 �� space for the air and then a clear plastic cover. Air would enter through a 5� hole at the lower right had corner and then with baffles was forced to zigzag it way to the top to the exhaust hole.

With the outside temperature in the 60�s and just normal air flow through it, the output temperature was consistently around 140 -150 degrees. Adding a small fan to force air through dropped the temperature to around 95 degrees but produced nice warm breeze.

Unfortunately with it leaning against a post I was not able to warm up the backyard but if it were mounted on the south side of a house and the hot air allowed into the room it would certainly help warm that room. This is something that is relatively easy to build and once built is virtually maintenance free.

I like it.

Dan

I like it also, but I would try a bit of simplification:
I would leave out the styropfoam based on the
thought that the transit time of the heated air
is too short to need it very much.

__________________
Imagined knowledge kills learning . . .
The cure for boredom is curiosity...there is no cure for curiosity..

Without the styrofoam the I'm pretty sure the heat lost from the backside of the metal would cause its temperature to drop too much. But you got thinking I wonder in place of the insulation what if the air was allowed to flow on both sides of the metal heat absorber? This should effectively double the heating surface!


Arrow, and anyone else, here is a site selling LED's. They have all sorts of sizes and shapes. Prices appear somewhat reasonable.
https://www.dealextreme.com/products.dx/category.907

This is awesome! I love your brain!!

__________________

The art of medicine consists of amusing the patient while nature cures the disease.
~Voltaire~

I saw something on your line of thinking on the green channel last year.... they had a large window at the base of the house with black cement somehow behind it.... according to the report, it was able to sufficiently heat that room without any other heat source... i keep wondering how you would build something like that... I like your idea! Now just wish I had the resources and the building knowhow to accomplish that!

__________________
God is and all is well
~John Greenleaf Whittier~

Hey Bergy, can you describe your heat pump configuration a bit
more? Here in the mexifornia foot hills they just exchange outside
air which is very inefficient. If I was starting with a vacant lot I'd
have a perimeter trench as deep as I could arrange for my exchange
piping. If you can't do that a heat pump is not worth much, it seems
to me.

Thanks

__________________
Imagined knowledge kills learning . . .
The cure for boredom is curiosity...there is no cure for curiosity..