Something rated for so few wouldn’t be a good heater. At 1.5 kw that typical cut off for small devices in USA. You draw 12 amp. Plug it into a larger 240 vlot circuit and it draws amps but you still only get 1.5 kw of heating. Same time to boil water
Well yeah.
But if both are rated for 6 or 8 Amps and can only supply 240 or 120V, you are bound to that.
Thus the volts are important as well.
Something rated for so few wouldn’t be a good heater. At 1.5 kw that typical cut off for small devices in USA. You draw 12 amp. Plug it into a larger 240 vlot circuit and it draws amps but you still only get 1.5 kw of heating. Same time to boil water