Dishwasher water supply - hot or cold?

New Bosch dishwasher which will take either cold or hot water supply. Given that we have recently replaced the DHW system with a reasonable WB CDi combi I take it that using the hot water supply will result in improved efficiency/lower operating cost, or is that too simplistic?
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rbel

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On Saturday, 2 February 2013 18:00:42 UTC, rbel wrote:

It depends on the delay/length of pipe run present in your system. You could have a situation whereby the dishwasher is full before much if any heated water reaches it, in which case you'll be wasting gas heating water most of which won't get used.
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In terms of energy efficiency an electric water heater is best as very little energy is wasted - only cable loss. However to convert that to cost comparison is a little more difficult.
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bert

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<rbel> wrote:> New Bosch dishwasher which will take either cold or hot water supply.

Cold every time, unless you have a free store of hot water. As has been said, the length of run makes a difference, dishwashers use maybe 3 litres of water, by the time the boiler has kicked in and got to temperature, the washer may already be full, so you'll be paying to keep the pipes warm.
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+1 Also if you use hot water,it sets the food hard in many cases making it harder to wash off,whereas cold water gradually heated removes food better. All the same applies to washing machines.
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In some cases, actually, mostly with egg yokes.

Particularly with the initial cold rinse that washes the egg yokes away before heating the water.
Not sure that it needs to increase gradually.

Nope, there isnt much dirty clothes wise that benefits from that approach and few washing machines have an initial cold water rinse for that reason.
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Cold. It'll probably never get any hot water - just the cold from the pipe.
Also, our dishwasher has warnings about it not cleaning properly if hot fill as it relies on a cold rinse to help remove things like egg yolk. Fill it with hot and it bakes it on. I suspect the detergents are designed to be started with cold and then warmed up as well.
Darren
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On Sat, 02 Feb 2013 18:00:42 +0000, rbel wrote:

If the dishwasher is by the sink, run the hot tap until hot comes through then turn on the dishwasher :-)
Although our previous Bosch dishwashers have recommended cold fill.
Cheers
Dave R
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On 02/02/2013 18:00, rbel wrote:

Cold is usually preferred since they don't draw much water anyway, and filling with hot water will just "set" some protein based stains making the job of the detergent harder.
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On Sat, 02 Feb 2013 18:00:42 +0000, rbel wrote:
Many thanks for the advice, I will use the cold supply.
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rbel

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On Saturday, 2 February 2013 18:00:42 UTC, rbel wrote:

To clear up efficiently comments.. Yes electric heating is locally (at poin t of use) almost 100% efficient, however it's actual generation is not so e fficient. A hot water boiler is more efficient at producing hot water for a given amount of hydrocarbon fuel than a power station is at producing that amount of electricity. Cost of electricity per kW is also higher then the cost of gas, for that efficiency reason. However, if you do not run the hot water before running the dishwasher, you will as described get very little actual hot water in the dishwasher, which drastically reduces the efficien cy and means the difference is difficult to assess either way.
Moral of the story is, if you run the hot water first you will be much more efficient, and if you have free solar hot water it is a no brainer.
As for the egg whites, we are talking of uncooked egg whites surely, presum ably mixing dishes for baking.. so rinse them before you put them in the di shwasher...
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On Sat, 29 Apr 2017 08:02:43 -0700, julian.muirhead wrote:

He's probably washed quite a few dishes in the past 4 years since his query!
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Makes a lot more sense to supply the dishwasher with cold water and let it do the rinsing itself.
Fuck all water is used, so the efficiency doesn’t matter, what matters is the effort to get the load done.
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2013? I bet its been solved by now. Brian
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