The heat exchanger, or “wort chiller,” is a set of stainless steel plates that are separated by rubber gaskets and are housed in” between two end pieces that frame the plates inside. The boiled wort is pumped through one series of plates in the heat exchanger while cold water flows through another series of plates. The rubber gaskets keep the two flows from mixing. The end result is that the cold water cools the metal in contact with the wort and the wort heats the metal contacting the water. As the wort passes through the heat exchanger, it is cooled to fermentation temperature and ready for transfer into the fermentation tank.