Espresso machine boiler types, explained

Boiler architecture is the single biggest spec decision — it sets whether you can brew and steam at once, how stable your temperature is, and most of the price.

Single boiler

One boiler heats for brewing OR steaming — you switch and wait between. The classic learner's architecture: cheapest path to real espresso, slowest workflow for milk drinks.

Thermoblock / thermocoil

Heats water on demand through a metal block instead of holding a boiler tank. Fast to ready, compact, common in entry machines; temperature stability is the trade-off.

Heat exchanger (HX)

A single boiler kept at steam temperature with a heat-exchanger tube drawing brew water through it — so you can pull a shot and steam milk at the same time. The prosumer sweet spot.

Dual boiler

Separate boilers for brew and steam, each independently temperature-controlled. The most stable, most flexible architecture — and the most expensive.