A thermoblock or thermocoil takes water from the reservoir in an espresso machine and heats it on the fly, versus heating up a full boiler of water. This technology is commonly seen on home espresso machines, where it manages either the brew function, steam function or both. The benefit of a thermoblock is that it doesn't take as long for your machine to heat up for either brew or steam; however, the drawback can be that your temperature for brew or steam is not quite as consistent as you might like.

Gail introduces us to a few different varieties of thermoblocks/thermocoils and shows how they compare to a standard boiler (specifically, the internals of the Breville Dual Boiler).

Special thanks to Breville for providing the sample internals for this video!