I would be very interested in hearing of personal experiences with a residential gravity-fed hot water return. An article I read about this way of insuring an almost "instant on" of hot water seemed really intriguing and if it really works it certainly would be something I'd like to pursue. The basic idea is to junction the hot water supply line at its farthest point in The House and return that back to the hot water tank so that the water in the hot supply is always hot, which would mean little (if any) waiting. Since we were planning on doing some renovation anyway, I thought it would be worth a try. But then I read other articles that whose opinion was exactly the opposite, saying that a gravity-fed return was not only a huge waste of time to have installed (or even as a DYI project), but was also a huge energy hog. I presume they took that position even though the supply line and especially the return should be well insulated. Your input is greatly appreciated!