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Single Boiler vs Dual Boiler

When brewing espresso drinks there is a need for two different temperatures. Espresso is prepared best when the coffee is extracted at temperatures well below boiling point, around 198-204F. However, when it comes time to steam milk for lattes and other milk-based espresso drinks, this requires a large amount of steam at a temperature well above boiling.

There are varied methods that manufacturers use to tackle the issue of handling two temperature outputs. One system includes a single boiler with a dual thermostat, which allows you to control the temperature in the settings panel while you are at each step in the drink making process. It takes more time (up to several minutes) though, for the machine to acclimate to each setting.

An alternative system includes a (DB) Double Boiler set up within the machine. One set up for brew temperature, and one set to steam temperature, which allows for the preferred temperature at each output phase without lag time.

A third option are (HX) Heat Exchanger machines, which utilize a single boiler that keeps the water at steam temperature but uses a cool water that is flash heated instantly to brew temperature when ready for pulling the espresso shot.

There are ongoing debates around which machine, DB or HX produces the best results. Both give the option to produce espresso and steamed milk simultaneously. Both can be plumbed, or utilized as a countertop machine. They both generally offer rotary pumps that keep noise levels down, and PID control of shot temperature. Though, PID control may actually have less impact in a HX machine due to the flash heating element in the boiler.

The main consideration to take into account when deciding which type of machine is best for you, is understanding how you will be using your machine. Will you be mainly making espresso, or lattes? How often and for how many people? Do you want maximum control over temperature so that you can cup various espressos and compare flavor profiles?

For a list of popular home espresso machines, like the Slayer Single Group (pictured), which features a double boiler, visit ChrisCoffee.com, as they are the largest distributer of home brewing machines.


Chris' Coffee Staff

Starting out of the back of an El Camino with the help of my family and a couple off duty cops, Chris' Coffee Service has been the experts in coffee since 1975.