What crazy ass compressor needs 220V 30A? Here in Netherlands heat pump is standard as new gas connections are banned for environmental reason, and most homes heat water and the whole house on 7 kW heat, 1.5 kW electric, or about 7A on 240V.
The backup element which only runs at extreme cold outside is a few kW yes but for hot water we just let it run dry and the tap gets colder, no big deal.
Dedicated hot water only boilers have a 300-700W compressor and sometimes a 1.5 kW backup coil. If electrical connection is an issue, just look for a pure compressor driven boiler.