Definition of Double Boiler Espresso Machines
Double boiler espresso makers, as the name implies, have in them two separate boilers (also called “dual boilers”). It is basically agreed by most, if not all, people that machines with double boilers provide the home barista with the best end result.
Machines that have double boilers normally also come equipped with each of the two boilers having its own individual control (heating thermostat), allowing one to heat water to a hotter temperature than the other.
The water that is heated to go through the ground coffee and extract the flavor from the coffee needs to be less hot than the water that is used for steaming milk.
If a machine with double boilers is used, both boilers can heat water simultaneously, with each boiler adjusted to the temperature needed for its particular function, whether it be steaming the milk or running through ground espresso beans to extract the espresso flavor.
Having a machine with double boilers not only ensures better results, due to using the correct water temperature for each needed function, double boilers also get rid of waiting between brews and steaming sessions.
With a single boiler, the water must be heated to the right temperature for extracting through the ground coffee. After that, there is a waiting period while the water heats up to a hotter temperature, which is necessary to achieve correctly steamed/frothed milk. This results in wait time, which a lot of people prefer not to have to do, particularly in today’s busy world of go, go go. This is the reason that so many people much prefer a machine that has double boilers over a machine that has just one.
There are other systems available with some espresso makers; however, the majority of them you will see have either one or two boilers as part of their water-heating system. Therefore, the subject of boilers is the only one that will be discussed in this page, at least for now.
For machines that have double boilers, below are definitions of the two different boilers, and what each boiler’s specific function is.
- Dedicated Brew Boiler – The boiler that heats the water for the coffee grounds: One of the two boilers is there simply to heat the water that seeps through the ground coffee and extracts the espresso down below into a waiting espresso cup or mug. This boiler heats water to a less hot temperature than the other boiler.
- Dedicated Steam Boiler – The boiler that heats water to be used with the milk-frothing wand: The other boiler of the two heats another, separate batch of water simply for steam (used for frothing milk with a milk steaming wand). This boiler heats the water to a hotter temperature than the other one.
Having two separate boilers prevents the water that is run through the grounds from being too hot and possibly scalding (burning) the ground coffee, while at the same time allowing the water that will be used for frothing the milk to reach an optimum (higher/hotter) temperature to allow for great steaming of milk.
Most espresso machines with double boilers have separate controls that are easily accessible, and many times digital, to allow the user to set each boiler to the optimal temperature for the function of that particular boiler.