Ok so I said that my project is floor heating. I'm the grooming chairman for the local snowmobile club. A few years ago we finally poured a concrete floor in our snowcat shed and as a last minute thought, I added 900 feet of pex tubing in the floor. The last two years I have been working on a hot water system for the floor. It is a hybrid system. It uses solar hot water tubes to circulate fluid from a collector tank to the tubes and back. It then uses three pumps to circulate flow to three different sections of the floor. I'm not trying to heat the whole building (24 feet by 48 feet) I'm only trying to get the floor a few degrees above freezing. Stage one is the solar side of the floor. Stage two is using the generator. When we have a function up at the snow park, we run our generator. It is a 21,000 watt, Kubota engine based generator. I have a 120v circulation pump that circulates fluid from the collector tank to a heat exchanger that is inline with the generator's radiator. It will pull more heat out of the generator in a half hour then the whole day on solar. The coolant from the generator never blends with the fluid from the floor. It is isolated. Why? It turns out that I installed the wrong pex in the floor. I should have ordered and installed an oxygen barrier pex. So I can't have any iron in the floor system or we will have some real rust problem. Everything on the floor circuit is brass, copper or plastic. No iron! Stage three is to add a rocket woodstove to not only heat the air in the building but there will be a 1 inch coil of copper pipe in the heat exchanger portion of the rocket that will thermally cycle with the collector tank. I told you it was complicated! Stage four has a 4000 watt electric element in the bottom of the collector tank. Stages 1,2 and 4 are completed.