On Fri, May 6, 2011 at 11:26 AM, M.L. wrote: > On Fri, May 6, 2011 at 10:27 AM, William Couture wro= te: >> Hi all, >> >> My wife has decided that we should get a tankless hot water heater to sa= ve >> energy. >> > > Why do you want to heat hot water? (sorry) > > Tankless water heaters come at quite a cost premium over tank units of > equivalent efficiency. If you have gas service, the most efficient and > economical option may be a "condensing" gas fired water heater. > > In general from what read, it seems that the ROI for a tankless system is quite long, or even non existent for a full family, shorter for a couple, and even shorter for a single person, I.E. the less hot water you use the more a tankless system makes sense. For the original poster, obviously there is a SWMBO in the picture, if there is kids in the picture or soon to be, or maybe even just planned, then a condensing 'tanked' water heater may be the best choice, as mentioned above. They even have heat-pump electric water heaters now, using a heat pump to provide heating for the water, cooling the surrounding area accordingly. It'd be interesting to see an absorption refrigeration style heat pump, gas powered water heater. Obviously not useful in all climates, but in places where heating requirements are small, it would seem like a good way to use energy rather then just dumping all those useful BTU's outside. --=20 Jonathan Hallameyer --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .