[squokko]

> this only makes sense in the US (or wherever else it's common for your dishwasher not to heat its own water).

American dishwashers heat their own water too - I think this is for cases when the dishwasher has a time limit on how long it will spend heating up the water (perhaps to meet expectations on cycle length).

[dwaite]

American dishwashers hook up to the hot water line, vs the cold water line in some other countries. They do have their own heaters, but household models are limited to 1200-1800 watts.

The pre-wash/pre-rinse cycle may only give enough time to raise the temperature 10-15 °F before the regular wash cycle starts. I do not believe they will delay the start of the wash cycle due to the water not yet being to target.

Starting with cold water reduces the effectiveness of the initial rinse, and may reduce effectiveness or prolong the wash cycle.