What Is A Group Head And How Does It Work?

If you ask me, there are two ways to look at making espresso at home. 

You can either keep it really simple, or… you can learn every little detail there is to know about making espresso, including every little part inside the machine.  

Of course, there are benefits to knowing absolutely everything about espresso making, such as…well, being an expert on espresso of pro barista proportions who can do it all and make virtually any drink there is and have it taste so great that people literally come to you for advice on a daily basis.  

Now, me being a person who wants things to be quick and easy, I like to keep the whole process rather simple.

• Grind your favourite coffee beans
• Press the grounds together with a tamper into a “puck”
• Pour pressurized almost boiling water through the puck
• Out comes a smooth coffee-based liquid love called espresso!

Voila!  See, that was easy, right?

And yet, people are always asking me questions, like…

“What is a group head and how does it work?”

I guess those people just figure since I had a nice, fancy Izzo Alex Duetto 3 that *I* would know the answer to that question. 

Well, it so happens I do know a bit about the parts of an espresso machine, but I still prefer not to complicate matters if I don’t have to.

That said, you can’t really talk about espresso machines without going down the slippery slope of actually knowing specific and specialized info.  Ah, so be it, let us make things a bit complicated then, shall we?  

For instance, does this diagram look fun and easy to you?

Yes, looking at the above image can cause some people stress. It looks complicated because it is, but if we focus in on one thing, like the matter of “What is a group head?” then we should be ok.  Take the image below.  This is a group head which has been cut open so we can see its inner workings.

Now this group head on its own doesn’t look like the easiest thing to understand, particularly if you’re not a handy-person type.  

Espresso machines are made up of fittings, gaskets, porta-filters, pumps, hoses, handles, thermostats, valves and group heads – they are not simple devices and you could really take a whole class on espresso machines if you wanted.  In fact, entire espresso courses are available out there right now, for the taking.

If you are an espresso newb, here’s a relatively short video that should demystify espresso machine for you somewhat, if you tend to think of them as overly complicated.

If you watched the above video, you will have heard the guy mention the term “group head” in reference to turning on your porta-filter. 

Basically, the area where your porta-filter attaches to your espresso machine is the group head, or, if you look at the picture on the right, its the area with the tiny holes which disperses water onto your fresh waiting coffee grinds. 

In other words, the group head is where the magic starts to happen when it comes to espresso. 

FYI, most commercial espresso machines use the famed E61 group head (like this one shown on the left from an Expobar Office Control espresso machine), which has its own unique advantages specific to that line of group head.

How To Clean Your Group Head

Here is a video which shows the cleaning of a group head, and in this video you will see the group head taken apart and so giving you a better idea of some of the smaller parts that go into it.

Check out this diagram of an espresso machine which will further explain whereabouts the group head is located on your espresso machine.  Its always good to look at different views of the same thing, to gain some perspective.

Making Espresso – How The Group Head Works 

Let us assume the coffee is already ground.  Then, we take our ground coffee and we attempt to get the best possible coffee puck in our porta-filter using a high quality tamper.

The porta-filter attaches to the group head with our tightly packed puck included, of course

As the water is warming up inside the boiler, your favourite fresh grounds are sitting in the porta-filter basket waiting patiently to receive that water.

Pressurized hot water is forced through the holes of the group head, showering the coffee grounds evenly. 

The evenness of this water dispersion is key to a quality group head, as is the temperature being kept at a consistent level.  

Shower Time

This is where the “shower” takes place.  The pressurized hot water controlled by the valve and the wand, shoots out of the group head evenly, showering the puck. 

This is the extraction part of the process.  We receive our shot of premium espresso by way of the hot water that is forced through the group head under high pressure.

Most home espresso machines use only one group head, while some commercial espresso machines use up to 7 group heads. 

The brass porta-filter retains the heat which is very important.  This filter forms a seal with the gasket and directs the hot pressurized water through the puck.  

Here is a video explaining how a “dual boiler” works.  This is another thing that will affect the group head – the boiler, and how it is set up.

Finishing The Job

That’s it!  The resultant thick, creamy extraction that drips out into the cup is the delicious, sought after brew that many people are searching for.  Of course, when the espresso is dripping out and into your cup, there is something to this process as well, such as watching for channeling or blonding, but that is somewhat of a different discussion, we feel.

And, as you can tell by now, the group head is a crucial part of the process because a lot of the espresso-making action is happening right at this critical point.

Depending on your level of know-how with your espresso machine, you can make your espresso a cup to remember, or a cup you’ll be wanting to soon forget.