[crazygringo]

If you have hot water, why wouldn't you use that for the water connection?

My dishwasher has a heating element, but the colder the water is, the more it has to work.

So if it's cheaper to use gas-powered hot water from the boiler than to heat it electrically, why wouldn't you? And it's there in the kitchen right next to the sink which has hot water available anyways, so it's kind of a no-brainer.

Yes, I'm in the US -- you can see on a kind of average dishwasher installation manual [1], it specifically instructs you to connect it to a hot water line.

[1] https://www.whirlpool.com/content/dam/global/documents/20101...

[adrianN]

My dishwasher uses sufficiently little water that it would get mostly cold water from the hot water pipe.

[crazygringo]

Yeah, the standard advice is actually to run your kitchen faucet on hot until you get hot water, before you start the dishwasher.

I'm always rinsing off the bigger gunks of food with hot water anyways as I load the dishwasher, so it's hot already.

At the end of the day it doesn't matter that much. The main point is just, if you have hot water available, it's hard to see why you wouldn't take advantage of that.

[adrianN]

I’d assume that wasting a lot of hot water before running the dishwasher negates any price benefits from heating the water with gas instead of electricity. Not to mention the CO2.

[nemetroid]

> If you have hot water, why wouldn't you use that for the water connection?

Two protein related reasons: hot water can denature detergent enzymes making them less effective, and hot water can cause food proteins on the dishes to harden and set.

European manufacturers claim that detergents work better when starting the program with cold water, and recommend doing so. The situation might be different in the US, where using the hot water seems to be the norm.