Group head
The group head is a vital part of an espresso machine, where pressurized hot water flows from the boiler to the portafilter for coffee extraction.
This part plays a key role in maintaining stable water temperature, directly affecting the flavor of the espresso. If the water is too cold, the coffee may taste sour; conversely, if the water is too hot, the Espresso can become bitter or burnt.
There are five common types of group heads: Electrically Heated, Conventional, Lever, and E61, each with its own mechanism designed to suit different types of Espresso machines.