I know how a dishwasher works. I’ve fixed it a couple of times => read the technical details. In the USA, it’s connected to the hot water supply on entry. Dishwashers have a weak heating element; it increases the temperature by only ~3°C/min, so heating up a full tray from scratch takes a while. It’s a good practice to run the hot water tap to warm up before starting the dishwasher. In countries with 220V, dishwashers often heat the water themselves. Bosch has an interesting solution: a heat exchanger in the wall. While the water heats up and is sprayed by the spray arms, a new batch of water pours into the heat exchanger. Then, the temperature of the new water batch slowly rises – while the ambient temperature in the chamber gradually drops, to avoid thermal shock for glasses when switching from dirty to clean water. And additionally, the heat exchanger provides a cold surface for drying – water from steam condenses there.
And everything stops not just on a timer (or rather, not only), but also by a turbidity sensor — an aquasensor. An infrared LED and a phototransistor inside the tray. It shines a beam through the water: strong signal received — water is clear, dishes are clean, time to wrap up; weak signal — too much dirt, need to keep running. That is, the machine itself decides whether to add a rinse. It also estimates the volume and dirtiness of the load — partly by the same turbidity, partly by how much the water cools when it’s sprayed onto the cold dishes (thermal mass) => the same Auto program can last either 1.5 hours or 3.
And here’s the most counterintuitive part. You should not rinse dishes before loading them. It’s not just soap, but a cocktail of surfactants (reduce surface tension), emulsifiers (make fats mix with water), dispersants (keep washed off dirt suspended so it doesn’t settle back), and enzymes (protease, amylase). Enzymes need food to latch onto. The main dirt on dishes is not fat (handled by surfactants and emulsifiers), but dried/burnt proteins and starches – large polymer molecules, insoluble in water and just mechanically adhering to the plate. You can’t knock them off with a jet, and there’s no one to rub them off. Enzymes — biological catalysts, cut these long molecules into small soluble pieces (protein into peptides and amino acids, starch into sugars), and these bits then easily wash away with water. Protease works on proteins, amylase on starch, sometimes lipase is added for fats. If you rinse everything off in advance – they just have nothing to do, washing off idly. If the aquasensor sees clean water at the start, it decides there’s not much to do, shortens the cycle, reduces intensity. Rinsing — you make the machine wash worse (but faster). Just scrape off solid chunks and load as is.
Insight about capsules. With each drain, water also carries away the dissolved detergent, so the machine injects the main dose only in the main wash — after it has drained the dirty preliminary water. But the pre-wash compartment is open, with holes, and the detergent leaks out right away. The capsule only opens in the main cycle, so for the first 10 minutes the machine runs clean water idly and no one is dealing with the fat then. That’s why powder is better than capsules: you can charge both compartments, and the pre-wash immediately tackles the fat.
Hi, I'm Rauf Aliev. 