[quickthrowman]

Yeah, I neglected to compare my hypothetical 6kW EWH against a 1500W HPWH, and did it against a 1500W EWH.

Heat pumps have no problem operating at a COP of 3-4, so the 120V 12A (1440kW) HPWH would be equivalent to a 240V 25A EWH (6kW)

[SigmundA]

AFAIK there are actually no 1500w HPWHs currently, the normal hybrid 220v models have a small 500 watt compressor thats very efficient and keeps the airflow requirements low which helps with installation placement and ducting if needed, then still have the electric elements if needed to boost.

The 120v model HPWH's I have seen do not have electric resistive elements and instead have around a 1000W compressor, so they recover faster purely on heat pump and can run off a standard 15 amp circuit while staying well under the NEC 80% rule which would be 12 amps, they are closer to 10 amps.

They do require more airflow and are generally noisier due to larger fans and compressor.

Then you have dedicated split system HPWH's like SANCO that use an outdoor unit like a minisplit and pull around 1800 watts putting well over 6kw into the water, these are probably the future or whole house heat pump systems that heat both water and air(and cool) as combined unit.