On Sat, May 7, 2011 at 2:02 PM, Jonathan Hallameyer wrot= e: > They even have heat-pump electric water heaters now, using a heat pump > to provide heating for the water, cooling the surrounding area > accordingly. I was going to mention those, but at the SEER they quote (3), it's not very economical unless you have no source of burnable fuel. Electricity is (from my calculations) several times more expensive than any combustible fuel. I just did a 2 minute search and I may be wrong about that. It might be closer to parity with oil (electric at a SEER of 3) What I wonder is why they can make household A/C units with a SEER of 14 but the water heaters only achieve 3. The delta-temp for A/C is going to be something like 90F hot to 55F cold (35 degrees) For water heating it will be something like 90F to 135F - so the delta-T isn't that different. --=20 Martin K. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .