Are you getting into espresso machines and slightly perplexed by the term "group head". This guide is for you!
In the details below, we'll explain...
- What a group head is.
- How a group head works.
- Group head cleaning and maintenance.
What is a Group Head?
The term "group head" when used in context of an espresso machine is where the portafilter attaches to the machine. Think of it as the first spot where water is pumped into before it hits the grinds that are sitting in the basket of your portafilter.
For some simple context, the portafilter is spoon-looking device with a basket where the coffee grounds are placed and tamped into. They're the devices that you'll see "sticking out" of an espresso machine.
The group head is equipped with "notches" where the portafilter locks into.
When in use, the portafilter is positioned up into the group head and then turned to lock in.
How Many Group Heads Do I Need?
Commercial Espresso machines are always defined by the number of group heads that they have.
Well - simply because it is a big determining factor of the volume and output that a machine can do. A one group machine means that you can only have one barista working on that machine at a given time.
Usually for a business, having a range of 2-4 group heads on their espresso machine is ideal.
At home, you really only need one unless you're doing some serious entertaining.
For a visual demonstration on how the group head and the portafilter interact, the video below from European Coffee Trip explains how to do the portafilter / group head insertion properly.
How a Group Head Works
While you may have been able to infer how the group head works and functions from the definition, here's a simplistic step-by-step break down of the espresso process with the group head at the forefront of the description...
- The portafilter coffee basket is packed with grinds and tamped.
- The barista inserts the portafilter up into the group head and locks it in by twisting it (but not over-twisting)
- The espresso brewing process (or pulling of the shot) is started by the mechanism of the given espresso machine. This could be as simple as pushing a button or by puling a lever on the more traditional machines. Obviously - the minute details of this process will vary.*
- Pressurized water flows through the group head and into the portafilter basket where the coffee grinds are.
- The water flows through the grinds and exits the portafilter (via spout(s) or bottom of a naked portafilter) into the espresso cup.
*Different espresso machines use different variations of pumps, boilers and water holding mechanisms to get the water to the group head. You can learn more about this on our guide to espresso boilers and heat exchangers.
Read Also: What is a Portafilter
Group Head Parts & Components
There are two parts of the group head that the average barista or business owner should be familiar with.
That's because these are the parts that should be cleaned on a regular basis (more on that in the next section).
- Screen: Portion of the group where the hot water comes down from. Should be cleaned regularly.
- Gasket: An o-ring inside the group head that helps create the seal between the group head and the portafilter. The gasket may need to be replaced when leaks occur.
As shown in this more technical diagram from the Nuova Simonelli Aurelia II, there are also a smaller series of attachments as part of the group head, but it's not critical to know them all.
How to Clean A Group Head
Group heads can get dirty, mainly because the screen can get full of residue and gunk from coffee grinds.
Here are a few signs that your group head might need cleaning...
- Shots aren't tasting right or having unique and distinctive flavor profiles.
- Water or coffee grinds are leaking from your portafilter.
- The pump is working extra hard to force water through the gunked up screen.
As an espresso machine owner, it is important to fully understand your machine and manufacturer's warranty for complex issues, but there are some simple steps that can be taken to clean most group heads quickly and easily...
- Use a short screw-driver to get under the group head and remove the screen.
- With a brush (not a pad that can strip the metal) and some water, clean off the screen until the all residue is removed.
- Clean the inside of the non-attachable part of the group head with a soft rag.
- Dry off all components and reattach the screen to the group head.
- Repeat this process regularly (monthly or bi-monthly depending on use) so that the residue stays soft and easy to clean.
- Solutions such as Cafiza Professional Espresso Machine Cleaner can also be used as part of the process.
See the video below to see group head cleaning in action...
Alternatively, there are tools that can be used to clean the group head such as a group head steaming brush. These steaming brushes work with the steam that's already on your espresso machine to clean the gasket and screen on your group head. The steam and the pressure make getting rid of grounds relatively quick and painless.
Here's what a steam brush looks like...
We hope that this guide has been helpful. You should now have a good understanding of the group head, but if not - please drop us a question below.
If you're looking for an espresso machine, please be sure to check out the following...