Washing machines and dishwashers. The newer models use much less water than the older generations did. By newer, I mean at least the past 10 years, maybe longer. Because the water used is less, the amount of time it takes for the unit to PULL the water is less, which means, even if you have your dishwasher hooked up to the hot water line, the water entering your dishwasher is probably not "hot" by the time the machine fills. The dishwasher relies on the water pulled to be hot, to heat up the dishwasher, for a proper washing, proper rinsing AND drying (even if you have a heating element).
Which means you are washing your dishes in tepid water. If the water used to wash the dishes does not reach a certain temp then the dishes may be getting "rinsed" really well, but aren't really "clean" if they aren't getting sanitized.
The solution to this (unless you have a unit that pulls the water from the cold line and heats the water itself, as mine does), is to run the water at the tap until it runs hot, THEN start your machine. Same goes for the washing machine, run the spigot at the wash sink, or if you don't have one of those, run it at the closest spigot to the washing machine.
With the "newer" ovens…. The old units (your mom's oven), used to maintain a constant temp. If the oven is set at 350, the unit heats to 350, then the heating element shuts off. When the temp would drop to say, 348 (or whatever the mfg's deemed to be "cooling") the heating unit would turn back on. Not very fuel efficient, BUT certainly efficient for a cooking perspective.
The newer ovens don't operate that way. If you set the temp to 350, the unit will heat to around 400, then the heating element kicks off until the temp reaches around 300, then it will kick back on again. Much more energy efficient. Now, you won't notice this much, if at all, if you are roasting a large piece of meat that is to be in the oven for hours, but you certainly WILL notice it if you can't seem to bake worth a darn anymore.
This can be "solved" by using your oven's convection setting (if you have one). I use mine when I am cooking or baking just about anything that will be in the oven for less than an hour. This keeps the oven at a constant temp. The repair man also mentioned using the convection setting for heating the oven as well, as it will heat much more quickly.
