Stainless Steel Holds Heat (Insulates) Better Than Plastic?

[DADoES]

</b>I'm probably going to regret this post ...<b>

I've read numerous dishwasher reviews that state along the lines of "we chose a stainless steel interior [instead of plastic] because it holds heat better ... more efficient ... less energy to maintain temperature during the cycle ... etc."

I would think plastic is a better insulator than stainless steel (or metallic materials in general). No?

For example, an aluminum tumbler containing boiling water would feel hot to the touch because the metal is not insulating very well, allows the heat to pass through. A plastic cup typically wouldn't feel so hot.

 

[earthling177]

Well, it's not that easy -- if you consider uninsulated tanks, yes, the plastic will be a bit better and also a little quieter. But newer dishwashers are not that simple, all of them are insulated to one degree or another, and my suspicion is that the ones with stainless-steel tanks are, in general, indeed better insulated, both acoustically and thermally, than the plastic machines, mostly because they fall in another price bracket and people would probably not tolerate an expensive noisy machine. On the other hand, there is also evidence that polished stainless steel is a powerful reflector for infrared radiation, which, all things being equal, will contribute to lower heat loss -- for example, a few years ago there was talk of several different appliance companies studying the use of a very high-efficiency insulator for freezers, fridges etc that was essentially a "vacuum tube" (like a thermos jug) but made with stainless-steel panels instead of glass. YMMV.

 

[toggleswitch2]

"By holding the heat" they mean gets hot itself, not preventing its movement (insulating)

 

[Brent-Aucoin]

I agree with Steve.
I think they are talking about stainless getting hot itself.
Every time I have read articles about stainless and dishwashers, they seem to bring up how the dishes seem to dry better.
Brent

 

[jons1077]

Stainless Kenmore

I had always had plastic dishwashers (cheap models) until a few years ago. I know it's not a good comparison necessarily but this stainless tub dishwasher gets hot as the dickens. I can't touch the dishes for a good hour after the cycle is done. I definitely think the metal and insulation together have something to do with holding in that heat.

Sorry, that's about as smart as I am on this subject!

Jon

 

[tomturbomatic]

Stainless steel has some unique properties. If you think about stainless steel and aluminum cookware, you need to use a lower heat setting with stainless than aluminum when using skillets. In the General Electric range manuals of years past, where they discuss materials for cookware, the note under stainless steel says something to the effect that it performs well at one heat setting lower than the one for aluminum. I notice this in all of my stainless steel cookware, no matter what type of metal in the base. When I make hash browns, I can use medium high under an aluminum skillet, but medium or below under a stainless steel pan. Somehow the surface is hotter, which does not make sense, except for the factor mentioned by Paulo.

One of the main reasons that manufacturers began the switch from plastic to stainless steel dishwasher tanks was the fear that the mandated removal of chlorine bleach from detergents would cause bad staining of the tubs, making them look permanently dirty and causing people to think that the machine could not be cleaning their dishes well in such a bad looking tub. The paradox is that whether insulated or not, the plastic tank would absorb heat less readily than the stainless steel so more heat would have to go into a stainless steel tank, up to a certain point, usually through water heating. The payoff would come with drying when the stainless steel would be a hotter surface, radiating more heat toward the dishes which would help drying performance in machines without fans or even the large steam vents of previous models. This improved drying performance would be most noted in the drying of items in the upper rack where puddles are more likely to remain and which is farthest from the heating source if heated dry is selected. Drying in the upper rack is important because it is usually the first rack pulled out and if water drips down on the lower rack, especially on the flatware, the dissatisfaction rate among owners will be higher.