Boiler
A tank that heats and holds water in an espresso machine, offering steadier temperature than a thermoblock.
Boiler machines keep a reservoir of hot water, giving more stable temperature and stronger, longer steam for milk. Single-boiler machines pause between brewing and steaming; dual-boiler machines do both at once.
Boilers add size, cost and warm-up time compared with a thermoblock.
Why it matters for small spaces
Boilers improve milk steaming but make a machine bigger — a real trade-off when counter space is tight.