By: Mike D. Andrews
Source: http://www.articlesbase.com/coffee-articles/nothing-less-than-a-pump-espresso-machine-will-do-2897103.html
If you would like to begin producing espresso drinks at home, and you’re just learning about the various kinds of espresso machines, then you definitely have to understand the difference between a steam driven espresso machine, a lever and piston espresso machine, and a pump espresso machine.
The electric steam driven machine is the first one we’ll discuss. These are at the low end of espresso machines and cost the least. Steam pressure is what makes these machines function. Water in an airtight chamber is heated to boiling and then quickly forced through the ground espresso using steam pressure, and then right into a cup. The steam pressure produced by these type of machines reaches about 1 bar, far below the benchmark pressure needed to brew real espresso. These machines generally have a steam wand allowing you to froth milk to make a latte or cappuccino. In my opinion these kinds of machines should really not be regarded as espresso machines because the very best they can do is create a strong cup of coffee.
The second kind of machine we’ll discuss is the manual lever and piston espresso machine. Rather than utilizing pressure generated by steam, the pressure used in a manual lever machine to brew espresso is created by a piston which is attached to the lever, which, when pulled, forces the heated water through the ground coffee. This type of espresso device gives you complete control over the entire brewing procedure such as dosing, tamping, pulling the manual lever to pressure the water through the espresso grounds, and timing each of these operations. Moving the lever up moves the piston up which then brings pre-heated water to the brew group. When the lever is subsequently pulled down it forces the hot water, under pressure, through the ground coffee. The phrase “pulling a shot” refers to this type of device, since you really have to “pull” a shot. The manual lever and pistion machine are engineered to produce sufficient pressure, within the 8-9 bar range, to properly extract a proper espresso drink.
An experienced barista can make an excellent espresso using this kind of machine. But there’s definitely a learning curve connected with this kind of machine, but with practice you can produce a very high quality and delicious espresso drink utilizing a lever and piston device. Personally, I’d choose a mchine that was a little easier to use.
The final type of device that we’ll look at is the electric pump espresso machine. Previously we’ve looked at machines that used steam pressure and piston pressure to create an espresso. This machine, as the name implies, utilizes an electric pump to force water through the system. The pump pulls water from a reservoir and returns it into a tank that heats the water. After the boiler heats the water to brewing temperature the pump will first push water through ground coffee within the brew group. You have the ability to control the temperature of the water before the pump pushes the water through the system. There are three types of electric pump espresso devices: The semi-automatic, the automatic, and also the super-automatic espresso machine.
Some individuals think that a genuine espresso shot can only be made by “pulling” a shot with a lever and piston machine. But for those people who just want a easy, quick, and delicious espresso, the automatic pump espresso machine can do a darn great job of producing an exceptional, consistent cup of coffee.