Solar Heated Stock
This is a very nicely
done solar heated and insulated stock tank built around a standard galvanized
stock watering tank. The design includes good insulation, solar heat
collection, a reduction in exposed water surface for less water surface heat
loss. It appears to be straightforward to build with ordinary tools and
I'm proud to say that some of
the inspiration came from my
solar heated stock tank prototype, but CS has
transformed it into a much more practical and useable design.
CS is "CommonSense" on
the HomeSteadingToday Forum,
Alternative Energy discussion group. Thanks very much to CS for
making the material available!!
You can probably find CS on
the Homesteading Today Alternative Energy forum if you have questions.
Here are the description and pictures supplied
For the last three or four years, we've
insulated our stock tanks with composting manure with some success, but the
boxes were at the point of needing to be rebuilt this year. Since we had to
build boxes anyway, we decided to go with a different design altogether.
After reading about Solar Gary's solar-heated stock tank, I wanted to use
that idea and adapt it to incorporate a steel stock tank. We painted 118
gallon steel tanks black on one side, built a super-insulated box, including
an insulated floor, with a partial cover--about two thirds of the tank is
covered, with one third remaining open for the horses to access the water at
The tank is oriented with the long, black-painted side facing south, and
that side of the tank box has a clear panel to allow the sun to hit the side
of the tank and transfer that heat to the water in the tank. There is a 5-6
inch space between the side of the tank and the clear panel.
The box has a cover with a 22", pretty much
square opening. This remains open at all times for the horses to access the
Below the plywood lid is a piece of 2" foamboard insulation that has a
matching opening cut into that. This piece of foam is sandwiched between the
top of the tank and the underside of the plywood cover.
Since the box is larger than the tank, placing this foamboard over the tank
on the inside of the box creates an airspace around the sides of the tank
that is warmed when the sun hits the black-painted side of the tank through
the clear panels. The air is trapped by the sides of the box, the sides of
the tank, and the foamboard on top of the tank.
We have had pretty cold temps for this time of year--0-2 degrees overnight,
teens to low 20's during the day, so we've had a chance to see the tanks
perform already. (CS is in Northern IL.)
We do get a thin layer of ice on the top of the water overnight, but it is
only 1/4-1/2" thick, and very flimsy ice that breaks with the push of a
finger. Last year, we needed to use heavy metal objects to break through the
ice that formed each night.
We don't use any supplemental heating elements at all. We do fill the tanks
every other day--we have 6 horses on each tank full time. Overnight, the
horses poke a hole through the ice to drink.
Horses like to "play" with things, so we added a couple of features to
safeguard the tanks...hog panels attached to the south side of the box to
keep hooves from smashing the clear panel and metal edging to keep busy
teeth from destroying the box. We used recycled plywood siding for the
outside of the box and bought new 2x4's and foam insulation. We used spray
foam to seal off the clear panel and any other potential air leaks.
I'm happy, I consider these to be quite a success!
The side of the metal tank that faces south is painted black to absorb solar
energy. The 2X4 frame allows space for insulation on the east, west, and
north walls, and supports the glazing for the collector on the south wall.
I think the cat likes it.
This shows the back wall. A
sheet of 2 inch thick foamboard insulation was added inside the 2X4 frame (this
is in addition to the 1.5 inch thick foamboard in the picture.
Frame just before the 2 inch
insulation board and tank are added. The solar collector glazing goes in
the large opening facing us.
Here is one of the tanks currently in
use. Overnight, we had single digit temps with wind. The first picture shows the
amount of ice that formed overnight. I took these pics at 8:30 a.m. (central)
and the sun is just about to start warming the tank. The tank gets good exposure
until mid afternoon, around 2:30 or so right now, with sunset starting around
Finished tank in use. Note the
corrugated glazing that is sealed on the ends with Great Stuff type polyurethane
foam in a can, and the hog panel to protect the glazing from the horses.
Finished tank showing the opening in
the insulated lid for the horses to drink through. The opening is
about 22 inches square.
CS will answer email questions at:
WhitetailRidge01 AT aol DOT com (change AT to @, and DOT to a
Gary December 10, 2008