Can someone please explain exactly how this thing works? Where does it get its heat from?
http://www.rheem.com/products/tank_water_heaters/hybrid_electric/
If it’s a heat pump, the heat source will probably be ambient - so it extracts heat out of the air and dumps it in the water, to heat it.
These devices typically have a frigid air exhaust - and it’s not uncommon for them to be more effective, in terms of hot water out, than a simple resistive heater. (and without violating thermodynamics).
It’s essentially a refrigeration unit, except the hot end is used instead of the cold one.
Reading the description on the spec sheet - yes - hot water comes out of the pipe, cold air comes out of the top vents - so if you place the unit in a part of your house that you are already heating, the heat pump feature is pointless, as it will only be leeching off the heat you’ve already paid for.
In simple terms…What makes a heat pump efficient is the the fact that they transfer heat to a different location as opposed to using energy or fuel to produce heat. An air conditioner is a heat pump. Where you direct the hot exhaust air or cool air is determined by what you want to heat or cool.
Heat pumps are typically3x as efficient as a resistive heater.
So it wouldn’t be a good idea for homes in Alaska (cold much of the time), but it might just work in Hawaii (warm all of the time).