Here I've seen different solutions. Some people simply add a T to the hot water pipe from the heater and run the circulation pipe alongside the hot water pipe connecting the two near the end. They then connect a pump to this. I don't really see how this has any effect. Wouldn't the hot water simply circulate endlessly and still cool at the same rate, since it's not being re-heated in any way...? A different way I've seen is pretty much the same as above, except that the T now connects the circ.pipe to the cold water pipe that supplies the water heater. To me this makes more sense because it forces the circulating water through the heater for re-heating. The backside of course is that if the circ.pump fails, you would get cold water in the circ.pipe, though it can easily be prevented using a one-way-valve. Have I got it right...?