system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can my fancy new dishwashers "ECO" mode last 5 hours? How is that good for the environment?
gpt
It takes very little energy to run the pump in the dishwasher.

It takes a lot more energy to run the heater.

When in eco mode, the washer isn’t running the heater, and only uses one small volume of water to wash and a small volume to rinse.  It just uses it for longer.

When in regular mode, it’s preheating the water and not reusing it, so it wastes electricity and water.