24/01/2026
Heat Exchanger Semi-Automatic Espresso Machine Explained.
A heat exchanger semi-automatic espresso machine uses one main boiler to produce steam and provide heat for brewing coffee at the same time.
The boiler stays hot and under pressure. Inside it runs a heat exchanger tube. Fresh water for brewing passes through this tube and is heated by the surrounding boiler water without mixing with it.
When the barista starts a shot, the pump increases the water pressure to around 9 bar. The heated water then passes through the group head, where the temperature is stabilised before extracting the espresso.
Steam for milk frothing is taken directly from the boiler, allowing coffee to be brewed and milk to be steamed simultaneously.
The machine is called semi-automatic because temperature and pressure are controlled automatically, while the barista manually starts and stops the shot and controls milk steaming.
