In this weeks show where it was stated that a heat pump water heater is more efficient because it uses only 700 Watts while the old one uses 4500 Watts sounds like total nonsense!
Electric heating is already nearly 100% efficient but a heatpump is not so it can't be more efficient than plain electric heating. Why were they promoting an expensive and much more complicated heatpump over the simple and reliable electric model?
The only savings I can see would be due to setting the unit to only run during off peak hours when the electric company charges a lower rate. However a timer could be used on the old kind to get the same result. If the new unit is only rated at 700Watts that means it takes longer to heat the water, not that it's more efficient. It's also probably better insulated which would add more efficiency but I doubt it would ever pay for the high cost of the heatpump. Due to the heatpump blowing out cold air when it's heating it probably costs more to run overall if you consider the main heating system for the house would have to deal with the cold air so you are actually heating it twice. Therefore heating the water is going to cost more if you also consider the total cost of heating the water and the house too!
Anybody have experience with these and actual data showing it costs more or less with a heatpump?