Last season I fiddled around with the notion of building a heat exchanger and rigging it to our clothes dryer. But Im not tech enough to know just how to trick the dryer into running the cycle without its juice drawing, meter running, wallet draining on board heater. I made a long curling copper coil thingy that would fit inside an 8" pipe. It would probably need some fins on it to extract more heat from it though. Anyone know how many btu's or air temp it would need? Does any company make something like this already? My dryer has plenty of empty space inside for "alterations". Lets hear some ideas fellas.