This past winter I expanded the detail on my website, including a section on my Domestic Hot Water setup. When I generated the plumbing diagrams I made some errors. My apologies to anyone who tried to make sense of them. I've corrected the diagrams. The updated section is at http://www.nofossil.org/hotwater.html. This setup allows me to get three days of hot water out of a 40 gallon tank by using a pair of mixing valves and using my storage for preheating.