Something manufacturers don't seem to take into consideration is the water cooling in the pipes during these long cycles. I first noticed this insanity in the KDSS 21 and 22 I had. Both filled, then stopped, before circulating any water, to heat the water to spray on cold dishes. While the first wash was happening, the water was cooling in the pipes before the next fill. After the first wash drained, the load was not that warm because the heat from the 140F water was pulled out of it by the room temperature tank and dishes. The next fill was not all that hot because the water had been sitting and cooling in the pipes for some time. This must be terrible in places where the pipes run through the cement slab so that the water cools as soon as it is shut off. All of the delays while the machine is slowly heating water or taking long enough to wash each piece in the load individually means that water is sitting in the pipes cooling. If there is a temperature sensor, it means that you are going to be paying to heat water electrically even if you have a gas water heater and since most, if not all, domestic dishwashers operate on 115 volts, the water heating is very slow. Of course, they are trying to move us away from washing dishes in hot water so it will soon be a moot point.
I remember a Bradford portable dishwasher on display near the cash registers at our Grants. The lid had a big poster standing up touting "3 STAGE WASHING" so I started reading. I thought it might have to do with multiple wash arms or something. No. Apparently, the machine did not have a detergent dispenser so it filled and started washing. The first stage was at some low temperature range where heat sensitive proteins were washed off the dishes. As the heating element kept heating the water, the second stage started at maybe 120-125F and this was where starches were washed off dishes after sitting there patiently and holding their tickets while the proteins were being wisked away. The third stage was around 140F where grease was washed away. Now this had to take a while. I remember the Westinghouse roll outs with the guaranteed 140F wash with timer delay during heating and the cycle could easily take 90 minutes back in the 1950s. I guess washing that long and getting the wash water that hot, they had to clean things. I think it was a late 50s Consumers Research report on dishwashers where they measured the temperature of the water draining out after each phase of the cycle and the water was amazingly low, like 120F or less after the wash in most of the machines. The dishes were hot by the end of the dry cycle, but they were not washed at anywhere near 140F.
