Heated Water Trough for Livestock -- Using the Sun Here's an interesting project that I took on this month. With winter coming, and water troughs needing heat to stay thawed, I've put up with exposed steel troughs long enough. Why these things don't just come from the manufacturer with insulation wraps is a mystery to me. Three years ago, I built an insulated box for a water trough, and it is still effective. Now that we have more horses, we need more water troughs. Into the old water trough, I never built into it provisions for putting in insulation. I decided that the second cover would be better and have insulation. Download Steven's pdf file with plans to go with the pictures below... To insulate mine, I had plenty of particle-board and 2x4's lying around, so building a box to cover the trough was easy. I built this carefully, however, to ensure room for the insulation and not much wasted space around the trough walls. To capture some heat from the sun, I found a great idea from Build-It-Solar, and added a solar collector to one side. In that design, the water was held in by walls of plywood, lined with plastic pool-wrap. It is very efficient from the point of view of insulation, but it wouldn't survive the rigours of Alberta's winters. I needed a different way to build this water trough. Ruggedness is essential, because horses are like little bulldozers with teeth. Leaving a solar collector within reach of their hooves invites disaster. And if it isn't possible to throw in a floating water heater on seriously cold days, then there's no point in doing this project. A solar collector will not melt water when it's -30 overnight! Using a metal trough to hold the water was essential. Here is the steel tank, a pretty typical 4' foot long oval trough. For the solar collector to heat the water, the sunlight must be absorbed efficiently. I painted the water trough black. It turned out that the black paint was glossy, but I had a bit of matte left in a spray can, so I lightly sprayed that on the side that would be in the sun. Sun entering the clear panel hits the black metal water tank and passively warms the water. At the time, I had no idea how strong the effect would be. Now that it's complete, I can feel the effect when putting my hand under the lid. So far, I used only left-over materials from other projects (building a new barn, tearing down an old one, etc.). When it came to covering the solar collector, I had some translucent panel materials, which also happened to fit perfectly. Looking at them realistically, though, I realized that the fiberglass panels would not let much light through directly to the trough. A lot of energy would be absorbed into the fiberglass sheets themselves, defeating the purpose. I went to the hardware store and picked up a clear corrugated polycarbonate sheet (called "Suntuf"). It was easy to work with, and is very transparent. I packed foam insulation into the walls, including making an insulated base with a sandwich of plywood and foam insulation. The insulation in the walls is R=7.5, and the double thickness in the bottom would be about R=15. Insulation on top of the trough does two things. First, obviously, insulates the water from radiating heat from the top surface. Second, the top sheet of insulation blocks air circulation between the sun collector area and the air above the water. Why does this matter? Because you have to cut a hole in the lid! The horses are getting thirsty! With a hole cut out, the air above the water will almost always be cold. Wind makes that air circulate in and out of the hole. If the air circulation also cools the air in the solar collector, then the solar effect is diminished. There must be a seal between the two chambers. Here it finally is, facing south (it was sunset when I took the picture, so no more sunshine into the collector). The cut-out in the top is 12"x12"; just enough for the horses to poke their noses through. They took only a few days to get used to it. Some deliberate splashing of water on their noses was all it took to make them understand that the water was inside. Pieces of metal trim around the edges of plywood prevent chewing (did I say they are like bulldozers with teeth? I meant beavers!) Update: December 23rd. We've had two weeks deep cold without a break. Daytime temperatures have not gone above -10C, and most overnights have been -30C or worse. Winds come and go, and only 1/2 of the days have been sunny. The insulated water trough is doing very well. It requires 1/2 of the electricity to keep it thawed compared to an open trough. The floating electric heater is controlled by an appliance timer, so it only turns on for 3 hours at a time, 2 times a day. This is enough to keep it thawed even on the coldest days. Several hours after the heater has shut off, a thin (1/4") layer of ice is the most I've seen built up, and the heating cycle thaws that before the 3 hours are up. The other steel trough that I have is identical, but it is only covered with an uninsulated plywood box. This tank is in trouble at -30C, and requires frequent ice-bashing. The electric heater in this trough uses almost twice as much electricity, and it still doesn't keep up. I'm glad now that I insulated the new water trough, and maybe before winter's through I'll have the old trough insulated, too. Steven Fahey in SW Alberta