Dishwasher Heating Element?

[jpalarchio]

Somewhat of a random question, just something that came to mind as I was unloading the dishwasher...

At the bottom of my dishwasher is a circular heating element, I assume used to both heat the water during washing and used as part of the drying process to heat the air.

Given that the dishwasher runs on a 120v/15a circuit, I'm guessing it's no more than a 1000-1500 watt element.

Why is it that this element can be "dry-fired" but our hot water tank elements cannot?

 

[dyqik]

It'll be an ULWD element, designed for dry firing - compare the length/surface area to a 1500W HWD water heater element. ULWD water heater elements can be dry fired, and elements for other purposes can be rated for higher temperatures with different materials in construction (look at an electric oven element - it will happily run in 500F dry air!)

 

[processhead]

The element in your dishwasher is designed more like an electric oven element than a water heater element.

Its designed for operation in air.