Countries with 220-240 voltage outlets are great for electric kettles, they are 3000 watts. The US is 120 volts and Japan is 100, kettles are 1500 watts and take twice as long to boil.
Those 120v on demand units need a special aerator on the faucet to slow the flow WAY down. They have more expensive larger voltage units to do what you probably want. Electric is best to heat water slowly in an insulated tank, not tankless on demand.
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