How Does a Percolating Coffee Pot Work?

The Percolator is one of the more familiar methods of brewing coffee in the U.S. It works by sending boiling water upwards, through a tube to the top of a perforated basket, where it rains down over the coffee grounds, and back down into the boiling water to start the process repeatedly.

How does a coffee percolator know when to stop percolating?

As the brew continually seeps through the grounds, the overall temperature of the liquid approaches boiling point, at which stage the "perking" action (the characteristic spurting sound the pot makes) stops, and the coffee is ready for drinking.

How does an old fashioned coffee pot work?

The mechanics are simple: Through the process of convection, as the temperature of the water rises, it moves away from the heat source. The resulting bubbles are pushed upward through a hollow stem in the middle of the pot and into the chamber up top that holds the coffee grounds (coarse ground is essential!).