Do Dishwashers Need Hot Water?
Dishwashers DO need hot water.
In order for the dishwasher to melt grease and the dishwasher detergent to dissolve, dishwashers require a water temperature of at least 140°F.
Save Money by Purchasing the Right Dishwasher
Though they cost more initially, purchasing a dishwasher with a booster heater will generally pay for itself within the first year. A dishwasher with a booster heater will raise the temperature of the water running through the dishwasher allowing you to set the water temperature running throughout the house to a lower setting.
How to Lower Your Dishwasher Usage Costs
Run only full loads. If you are using an Energy Star® rated dishwasher and only fun full loads, you will actually save money over hand washing the same load of dishes.
Purchase a dishwasher that offers a variety of cycle setting that can accommodate both small and large loads. Small capacity dishwashers don't always save money. Though it's true that running a smaller dishwasher is more energy efficient than running a larger one, if you need to run it more than once it is likely costing you more.
Choose a dishwasher model that offers energy saving options such as an air dry cycle and shorter cycles for fewer dishes.
Install your dishwasher in a location that is not abutting the refrigerator. The heat and moisture produced by the dishwasher makes your refrigerator have to work harder.