After finding out how standard drip coffee machines work, I am not surprised that some models in the not to distant past have been recalled for posing a fire hazard. Typical coffee makers are 95% plastic, yet there is a hot plate and a super hot aluminum apparatus that heats the water from cool to boiling in a few seconds. This is a pretty nifty trick if you ask me.
Another interesting aspect of this super-hot, super-fast heating mechanism is: There’s really no mechanism at all. The boiling water itself and gravity are the only forces that move the water through the machine onto the coffee grounds.
Also, there is a one-way valve that allows the water to pass through the aluminum heating coil, thus preventing super heated water backwash.
When the water heats to boiling, this pushes the water up and out until it is “dripping” onto the coffee grounds. As the heated water pushes itself up and out, this creates a vacuum that draws more cool water in from the reservoir, thus continuing the cycle until all the water in the reservoir is gone.
As the water comes in contact with coffee grounds, gravity pushes the water through at just the right speed to create a perfect, balanced pot of joe. As long as the coffee grounds aren’t too fine or coarse then the water will cycle through at the right pace to saturate the coffee and extract the desirable elements (flavor, caffeine, etc.). This is the “drip” method is ideal — the beans should only be in contact with hot water long enough to be “spent” but not boiled into oblivion.