Dishwasher hookup question

Do you hook yours up to the hot or the cold input? Some say hot but others say it doesnt matter since the dishwasher has its own heating coil.

If you use electricity to heat your water then cost will not change much.
If you have a cheaper source of hot water then that should be better.
But first read the manual that comes with the machine, what does it say?

Your hot water tank is generally better insulated than your dishwasher. It should be able to heat water more efficiently than your dishwasher even if you use electricity for both. To maximize heating efficiency, run the hot water at the sink before turning on the dishwasher to flush the cool water out of the pipes.

Do what the manual says. But generally you want to use the hot water line if it’s available. As others have said, your water heater will heat water more efficiently than the dishwasher. The dishwasher will heat water more, since it generally wants hotter water than your faucet, but if it starts out already hot, the dishwasher has to work less.

This varies greatly.

In Europe it is pretty much always the cold water only. One key reason being that some cleaning agents are far less effective at high temps so by only having a cold infill and heating as needed to the right temperature, you avoid that problem.

But yeah, check your model.

Hot water tank may be better insulated, but keep in mind the hot water tank needs to run water through quite a bit of plumbing before it gets to the dishwasher. Even with line insulation, there’s going to be a non-zero amount of heat loss by the time it gets to the dishwasher, wheras if the dishwasher just heats it locally from the cold line, you’re not dealing with any of the line losses.

Also, I believe many current dishwashers are designed to cool down the walls with cold water prior to the dry cycle in order to pull condensation from the dishes. At least I think that’s how it works.

Bottom line is do whatever the manual says.

When our kitchen was remodeled about 15 years ago, the plumber used by the contractor was a moron. (Well, the electrician and the painters and the carpenters were all morons, too, but that’s another post.) The plumber replaced pipes in the basement (part of the project) and switched the hot water and cold water feeds to the kitchen.

The dishwasher didn’t work worth shit when it got the cold-water feed. This was largely due to my forgetting at first that I had the dishwasher’s own water heating turned off on the control panel (more ecologically sound), but even after I turned the “power miser” function off, it still didn’t work that great.

Moron plumber did fix the problem, but instead of replacing the pipes in the basement, he just put in some elbows so we have this double-helix kind of thing going on.

That’s not evidence of bad plumbing. That’s built-in original art. Price the house accordingly when you sell. :slight_smile:

When we installed our dishwasher it not only stated to connect to the hot water, but it also instructed for better operation to run the water at the sink until hot before starting the dish washer. In heating the water there is a time element. If you start with cold water the dishwasher will be part way through the cycle before the water is hot enough to properly wash the dishes.

Likewise, running hot water at the faucet to bring it up to temperature before starting the dishwasher is something I’ve become acclimatized to doing for many years.

FWIW, I’ve never seen a dishwasher that wasn’t connected to the hot water, but from previous postings apparently they exist. Maybe it’s a regional thing. The manual for mine even states a minimum hot water input temperature. It does have the ability to heat the water but it’s a selectable feature. I usually just hit “standard wash” and I don’t even remember if water heating auto-selects or not.

As always, read the installation manual!

I had no idea that some dishwashers heated the water.

Most dishwashers heat your water. They also bake your dishes to dry them. The heating element is usually down at the bottom of the dishwasher, just under the rotating water squirting or diverting blade.

You can usually turn the heat off so that you aren’t as likely to melt certain types of plastics. Often this will be labeled in a confusing way, such as “energy saver dry” which you have to turn ON to turn the heat OFF.

The heating element on some dishwashers is a bit under-sized, which is why the manufacturer may want you to connect the dishwasher to hot water. That way the heating element doesn’t have to work as hard. It also makes the dishwasher seem more environmentally friendly on its energy consumption numbers, since it lets the hot water tank provide most of the energy to heat the water.

Does the heating element heat the water directly, or heat the inside of the dishwasher?

The heating element sits down pretty low in the dishwasher, so when the dishwasher is in wash mode, the heating element heats the water that is in the bottom, then the sprayer takes the hot water and sprays it over your dishes.

When the dishwasher gets to the drying cycle and all of the water is drained out, it heats the inside of the dishwasher basically like an oven.

I find this hard to believe. What possible dish cleaning agent will work better with colder water?

Don’t some/most clothes washers in the UK and/or Europe heat their own water? This is unheard of in the US, and I used to think dishwashers were the same way. That the heating element in the bottom of them was only for fast drying. Regardless, heating water with an electric coil (and a 110V one at that) is not going to be significantly more efficient (i.e. cheaper) than using your house’s furnace’s hot water (unless it too is electric). So I would expect you would always hook it up to the hot water line.

But, again, go by what the manual says (though I would be really surprised if it said ‘cold’)…

I’m going to open the door periodically next time I run it and see if the little light stays on. :slight_smile:

All the dish and clothes washers I ever owned have been cold water feeds. This is the standard across the EU. Maybe we are more energy and water concious here.

My washing machine instructions say that it is OK to use a hot feed, but point out that it uses so little water that it will probably not have run hot by the time it switches off. My dishwasher runs a cold cycle to rinse the dishes off before it heats up, it would be a waste to use hot water for this.

The idea that heating water in a tank is “more efficient than a dishwasher hot water tank” is plain nonsense. If the fuel is the same then it costs the same to heat a given amount of water. In addition, the machine only heats the amount of water that it needs and this is surprisingly little with a modern ‘eco’ machine.

I would guess it has more to do with central heating and running hot water being ubiquitous earlier & longer (and cheaper) here. And electric central heating, even just electric hot water heaters, are not overly popular here because they are significantly more expensive to use than oil or gas.

This is not the impression I have - do you have a cite for that? Many American houses have furnaces, while here we mostly have wet central heating. Most common water heaters here are continuous flow gas fired ‘boilers’ but many people still have a hot water cylinder heated by the central heating boiler in winter and electricity in summer.

The very rural house I was born in had running hot water until the 50s. It was not considered unusual.

I have a butane tank, and electricity is much cheaper for heating water and the house.