Thermoblock

A heating system that runs water through narrow channels machined into an aluminium or brass block, with heating elements embedded in the block. Heats water on-demand rather than storing hot water in a boiler.

Why it matters — Thermoblocks are fast-warming (under a minute, often) and compact, making them popular in entry-level espresso machines. The trade-off is that thermal mass is low — temperature stability shot-to-shot is poorer than a true boiler.

Good to know

• Common in machines like the Breville Bambino and many entry-level Italian machines.
• Thermoblocks generally don't tolerate dirty water well — scale clogs the narrow internal channels and can be impossible to clear without replacement.