Here's some 2014 research and advice on hot water heaters from the excellent Green Building Advisor site: "Deciding on a Hot Water Heater: Why we chose an electric water heater instead of a solar water heater."
UPDATE: August 2nd 2012, about 3 months of usage shows an increase in our electric bill of between $15 and $20 a month on Heat Pump Only setting. Well worth the install!
ORIGINAL Post: Installed End of March 2013: We’re finally off oil for our residential (bathroom, kitchen, laundry, etc) hot water! I’ve just completed the installation of a GE Geospring hybrid heat pump hot water heater. It’s really magical to know that our hot water is heated from taking the heat out of the air in our basement, and the byproduct is a dehumidifier and air circulator! Our basement is a consistent 65 degrees, either from the spill off heat of our oil boiler in the winter, and summer heat from upstairs in summer. It’s very well insulated. So far, we have it set for heat-pump only, so the electric coil doesn’t come on at all. The downside is that if you only use the heat-pump, the recovery time is much longer than a normal hot water heater. We’ve yet to run out of hot water, but we’re frugal, with only one bathroom, two people, and one baby. We have low flow shower and sink heads.
Our hot water baseboard is still from a Peerless oil boiler that’s about 10 years old. It’s a good boiler, pretty efficient for its time. But it was also heating our residential hot water, and with not storage tank or electric hot water heater. All summer the boiler would fire when we took a shower or did the dishes. I thought about on-demand, but we only have propane, no natural gas, and our basement is warm and while dry, it could always be dryer. Our basement is completely foam insulated, air tight.
Our 1907, 1300 square foot home in southern Vermont has been totally re-insulated with cellulose in the walls and 18″ in the attic. This brought us down from about 750 gallons of oil a year for heat and hot water, to 350 gallons a year.
The cost for the heater was $999.00 plus tax, on sale in MA at Lowes. The installation was about $500 since we had to run a new 220 line to a new breaker, and we needed a $170 mixer valve Vermont requires. So, about $1500.00. With this hot water heater keeping the furnace off all summer, and keeping it from firing extra in the winter, we forecast somewhere around $400/year savings. The heater does use electricity to power the compressor and fan, so we’re estimating that it will be $200/year in electricity at the most, so that’s $200/year savings. Not a bad projected ROI.