Heat Exchanger vs. Dual Boiler

Home espresso machines may produce the same delicious beverages, but the mechanics involved can vary from one machine to next. Two popular types of espresso machines that extract and steam milk at time are dual boiler and Heat Exchanger machines. Here we explain how they compare & contrast.

The Boiler(s)

As the name suggests – dual boiler espresso machines have two boilers, whereas a heat exchanger machine only has one. This is the most obvious difference between the two types of machines, yet both can produce the very high temperatures needed for steam and the below boiling temperatures needed for quality espresso.

How a Heat Exchanger Works 

A heat exchanger espresso machine like the Appartamento from Rocket keeps the water in the boiler at temperatures high enough to create steam, roughly 255 – 265 F. The steam boiler is half filled with water and has a heat exchange tube inside where water from the reservoir is fed into and flash heated before channeling it into the group to make the coffee. The steam valve above the water and heat exchange tube is where steam is pulled from to create steam and make your milk-based drinks. Heat exchange machines require cooling flushes to be done when the machine sits idle for a period of time, which is not the case for dual boiler machines.

Dual Boiler Machines

On the other side of the coin are dual boiler espresso machine like the Vetrano 2B Evo from Quick Mill. The steam boiler is kept at a higher temperature for steam while the brew boiler is put at a lower temperature for the espresso. Most all dual boilers come with a PID which allows you the ability to achieve shot consistency with extremely accurate brew temperatures. The PID allows users to make adjustments based on the type of coffee that is being used due to the fact that different water temperatures can create different flavor profiles in varying coffee origins.

Heat Exchange Buyer

Ideal for someone that does primarily milk-based drinks and is not as concerned about varying brew temperatures and wants to save a few hundred dollars.

Dual Boiler Buyer

Ideal for someone that likes to do milk-based drinks but also does a lot of espresso and cares about shot consistency with the ability to adjust brew temperatures.