Espresso enthusiasts such as myself often want to know how espresso machines work. That way, we’ll know how to use each part optimally. Hence, this guide came to life.
This guide will cover all the parts commonly found in espresso machines and some parts not found in every device.
Here is what we will talk about:
Let’s dive in.
- Variations of pumps, group heads, boilers, & water sources will impact price & functionality.
- Different versions of parts (e.g., pump) greatly affect espresso taste & consistency.
- Add-ons like pressure gauges & bean dosers can increase machine price.
- Not all espresso machines include steam wands, grinders, pressure gauges, & hot water taps.
Espresso Machine Parts & Functions
Here are all the common parts we’ll cover:
|Portafilter||Holds the coffee grounds & is inserted into the group head.|
|Group Head||Delivers hot water to the coffee grounds.|
|Pump||Pressurizes the water & forces it through the coffee grounds.|
|Water Boiler||Heats the water to the desired temperature.|
|Water Source||Provides the water for the boiler.|
|Drip Tray||Catches the excess water that drips from the portafilter.|
I’ll explain what each part is, its function, and if it has variations, I’ll cover the pros and cons of each. That way, you’ll know what to look for when shopping for an espresso machine.
A portafilter is a part of an espresso machine that holds the coffee grounds. It has 2 parts: the handle and the basket. The handle is the part that you grip, and the basket is the part that holds the coffee grounds.
Portafilters come in various sizes like :
|Brand / Model Name||Portafilter Size|
|De’Longhi (Older Models)||49 mm|
|La Spaziale Home Models||52 mm|
|New Breville Models & Rancilio Silvia||58 mm|
58 mm is the most common portafilter size.
There are two main types of portafilters: bottomless and spouted. Bottomless portafilters have no spouts. The former allows you to see the espresso as it’s extracted. This can prove useful for troubleshooting problems with your espresso machine.
Spouted portafilters have one or two spouts, which allow the espresso to flow into cups.
Here are the pros and cons of bottomless portafilters:
- Easier to troubleshoot espresso.
- Easier to clean
- More difficult to control.
And the advantages and disadvantages of using spouted portafilters:
- Easier to use.
- Less visibility.
- Longer extraction time than bottomless.
Let’s dive into different parts and attachments for portafilters.
1. Portafilter Basket
A portafilter basket is a metal filter inserted into an espresso machine’s portafilter. It holds the ground coffee and allows the water to flow under pressure, creating espresso.
Portafilter baskets come in a variety of sizes, shapes, and materials. The most common size is 58 mm, which is compatible with most home espresso machines. Other standard sizes include 54 mm and 53 mm.
All espresso machines include “stock” portafilter baskets. However, you could buy precision baskets that the brands IMS and VST produce. The latter is best for taste. The former, for budget.
2. Portafilter Filter Spring
A portafilter filter spring is a small, thin spring used to hold the filter basket in place inside the portafilter of an espresso machine. The spring sits at the bottom of the portafilter.
Without the spring, the filter basket could move around and cause uneven extraction or channeling. The spring also helps to create a tight seal between the filter basket and the portafilter, which helps to prevent leaks.
3. Group Gasket
A group or brew head gasket is a rubber or silicone ring. It creates a watertight seal between the portafilter and the group head of an espresso machine. It ensures water flows properly through the coffee grounds and into the cup.
Group gaskets can wear out over time due to espresso’s constant heat and pressure. When this happens, the seal will break down and water will leak out.
This leaking can cause many problems, including:
- Weak or uneven espresso
- Watery espresso
- Espresso that tastes sour or bitter
- Damage to the espresso machine
To prevent these problems, replace the group gasket regularly. The replacement frequency will vary depending on the make and model of your espresso machine.
4. Group Screen
A group screen, also known as a shower screen, is a perforated metal disc that sits between the portafilter and the group head of an espresso machine. It evenly distributes the water over the coffee grounds, ensuring a consistent extraction.
Group screens, usually made of stainless steel or brass, come in various sizes to fit different espresso machines. They can have a flat or angled design, and they may have a variety of perforation patterns.
Over time, group screens can become clogged with coffee oils and residues, affecting the flow of water and the quality of the espresso. Clean and replace group screens regularly to maintain the performance of your espresso machine.
What do all these parts connect to, though?
2. Group Head
A group head is a part of an espresso machine that the portafilter attaches to. It’s the heart of the device and responsible for creating a great cup of espresso.
Located on the front of the machine, the group head is a metal, permanent attachment that brings water out of the machine and into the filter basket.
The group head is made up of several parts, including:
- Portafilter holder: Where the portafilter locks into place.
- Brew head: Part of the group head that heats the water & delivers it to the coffee grounds.
- Showerhead: Small, perforated disc that distributes the water evenly over the coffee grounds.
- Thermostat: Controls the temperature of the water in the group head.
The group head is a critical component of an espresso machine, and its performance has a direct impact on the quality of the espresso. A well-maintained group head will produce consistent, flavorful espresso shots.
The differences among the different types of group heads are as follows:
|Temperature control||Precise||Less precise||Less precise||Precise||Precise|
|Ease of use||Easy||Easy||Easy||Easy||Easy|
And now we’ll discuss pumps.
The pump is responsible for creating the pressure needed to extract the espresso.
The ideal pump pressure for espresso is 9 bars. This is the pressure needed to extract the flavor and aroma from the coffee grounds.
Some espresso machines have pumps producing up to 15 bars of pressure. This isn’t necessary and can make the espresso taste bitter.
When choosing an espresso machine, consider the pump type used.
Rotary vane pumps are the best option for most people, but vibratory pumps can be a good choice if you’re on a budget. It’s also essential to ensure that the pump can produce 9 bars of pressure.
1. Vibratory Pump
- Cost-effective: More affordable than rotary pumps.
- Compact: Smaller machines; great for small kitchens.
- Limited consistency: Could impact your espresso’s consistency.
- Unusable with direct water line machines: Can’t use these pumps with devices that directly connect to home’s pipes.
Vibratory pumps work by using a piston or diaphragm to create a vacuum. The vacuum draws in fluid, which is then forced out by the piston or diaphragm as it vibrates. An electromagnet creates vibrations powered by an alternating current (AC) source.
Vibratory pumps are inexpensive and easy to maintain. They are also quiet and compact, making them ideal for espresso machines. However, they aren’t as efficient as other types of pumps, such as rotary pumps.
2. Rotary Pump
- Quieter operation: Better for not producing a lot of noise in the mornings.
- Longer lifespan: Can last more than 15 years .
- More consistent pressure: Builds up pressure quicker than vibratory pumps.
- Larger: Leads to larger devices, which aren’t good for smaller kitchens.
- More complex: More complex than vibratory pumps, which can make them more difficult to repair.
- Higher cost: 10–20 times more expensive than vibratory pumps.
A rotary pump is a type of pump that uses a rotating impeller to move water. This pump type is typically quieter and more efficient than vibratory pumps. And they can provide a more consistent water pressure, which is vital for making espresso.
Rotary pumps work by rotating a disc that’s offset by a cylindrical chamber. As the disc rotates, it creates a vacuum that draws water into the chamber. The water then pulses out of the section by the rotating disc.
Many espresso machines connected to a water line use rotary pumps. This allows the pump to maintain a constant water pressure. This perk’s also excellent for commercial espresso makers.
Let’s see what heats all this flowing water.
4. Water Boiler
A water boiler in an espresso machine is a chamber that heats water to the ideal temperature for brewing espresso. The temperature of the water is important for extracting the flavor from the coffee grounds and creating a good crema.
The 3 main types of water boilers in espresso machines include:
- Single boiler: Heats water to a single temperature, which is usually around 195–205 °F.
- Cheap machines, but can’t froth milk & brew coffee simultaneously.
- Dual boiler: Has 2 separate chambers, one for brewing & one for steaming.
- More expensive than single boiler machines, but they offer better temperature control & flexibility.
- Heat exchanger: Uses a heat exchanger to transfer heat from the steam boiler to the brew boiler.
- Less expensive than dual boiler machines, but they do not offer as much flexibility or temperature control.
- Can brew coffee & froth milk at the same time.
The best type of water boiler for you will depend on your budget and your needs. If you’re a casual espresso drinker who makes a few drinks a day, a single boiler machine works best.
If you’re an espresso enthusiast who makes multiple drinks a day, a dual boiler or heat exchanger machine is a better investment.
Here’s where the water comes from.
5. Water Source
Here are the main water sources for espresso machines:
- Water reservoir: A tank that is located inside the machine & can be filled with tap water.
- The water is then heated by the machine & used to make espresso.
- Direct plumb: Connects the machine directly to a water line.
- This eliminates the need for a water reservoir & ensures a constant supply of fresh, filtered water.
The best water source for your espresso machine will depend on your needs and preferences. If you’re a home user and don’t have hard water, then a water reservoir works best.
A direct plumb system may work better if you’re a commercial user or have hard water.
Not all that water’s going into your cup. Some may overflow into this—
6. Drip Tray
A drip tray is a component of an espresso machine that catches the excess water and coffee grounds produced during the brewing process. It’s typically made of plastic or stainless steel and has a lip that prevents spills.
Drip trays are essential for keeping your espresso machine clean and preventing messes on your countertop.
Moving on to parts that not all espresso machines include.
Parts Not Found on All Espresso Machines
Some espresso machines will contain the following parts and components:
|Hot Water Tap||Dispenses hot water.|
|Group Dosing Keypad||Sets the amount of coffee to be dispensed.|
|Group Dispense Switch||Dispenses coffee.|
|Pressure Gauge||Measures the pressure of the water.|
|Sight Glass||Shows the amount of water in the boiler.|
|Steam Control||Controls the flow of steam for frothing milk.|
|Steam Wand||Steams milk.|
|Bean Hopper||Stores coffee beans.|
|Bean Doser||Measures the amount of coffee beans to be dispensed.|
|Grinder||Grinds coffee beans.|
Again, I’ll discuss what each part does and compare any variations (if any).
1. Hot Water Tap
A hot water tap is a feature on some espresso machines that dispenses hot water for tasks such as making tea, hot chocolate, or instant oatmeal. It’s usually on the side of the machine, near the steam wand.
The boiler that heats the water for espresso also heats the water tap.
Let’s get back to things related to espresso.
2. Group Dosing Keypad
A group dosing keypad is a control panel on an espresso machine that allows you to set the amount of coffee dispensed from each group head. It’s typically a keypad with buttons for each group head and a button for dispensing a double shot of espresso.
Here’s another switch.
3. Group Dispense Switch
A group dispense switch controls the flow of water from the boiler to the group head of an espresso machine. It sits on the front of the machine, near the group head.
In semi-automatic espresso machines, the group dispense switch is a manual switch that the barista must press to start the water flow. The barista controls the amount of water dispensed by how long they hold the switch down.
In automatic espresso machines, the group dispense switch is usually a button programmed to dispense a certain amount of water. The barista can also override the programmed amount by pressing and holding the button for longer.
This next part will measure pressure.
4. Pressure Gauge
A pressure gauge for espresso machines is a device that measures the pressure of the water as it’s forced through the coffee grounds in the portafilter. The ideal pressure for espresso extraction is 9 bars .
A pressure gauge can help you to ensure that your espresso machine is producing the correct pressure, which will result in a better tasting espresso.
There are two types of pressure gauges for espresso machines:
- Brew pressure gauge: Measures the pressure of the water as it’s forced through the coffee grounds.
- Steam pressure gauge: Measures the pressure of the water in the boiler of the espresso machine.
If your espresso machine doesn’t have a pressure gauge, purchase one separately and install it yourself. Choose one that fits your espresso machine and your budget.
What if you want to know how much water your machine has left?
5. Sight Glass
A sight glass is a transparent window that allows you to see the water level in the water reservoir of an espresso machine. It’s typically made of glass or plastic and located on the side or front of the machine.
The sight glass is a valuable tool for monitoring the reservoir’s water level and ensuring there is always enough water to brew espresso.
Keep reading to learn more about controlling your machine’s steam.
6. Steam Control
Steam control is the process of regulating the flow of steam from the steam wand of an espresso machine. It’s important for creating the perfect steamed milk for espresso-based drinks such as lattes and cappuccinos.
The steam control valve usually sits on the side of the espresso machine, near the steam wand. You may see it as a knob, a lever, or a joystick. To use the steam control valve, turn it clockwise to increase the steam flow. Or counterclockwise to decrease the flow.
The amount of steam needed to steam milk will vary depending on the size of the pitcher and the amount of milk. You’ll want to start with a low steam flow and gradually increase it as the milk heats up. Once the milk is hot, use the steam to create foam.
Here’s what the steam comes out of.
7. Steam Wand
A steam wand froths milk for espresso-based drinks like lattes and cappuccinos. It’s attached to the side of an espresso machine and consists of a long, thin metal tube with a nozzle at the end.
When the steam wand powers on, it releases hot, pressurized steam into the milk, which causes it to expand and form foam.
There are two main types of steam wands:
- Manual steam wands: Requires the user to manually control the amount of steam & air being injected into the milk.
- This can be a bit tricky to master, but it gives the user more control over the texture of the foam.
- Automatic steam wands: Automatically injects air into the milk.
- This makes them easier to use, but they don’t give the user as much control over the texture of the foam.
To use a steam wand, first fill a metal pitcher with cold milk. Then, insert the tip of the wand into the milk until it’s about ½ inch below the surface. Turn on the steam wand and slowly move it around the pitcher, creating a vortex in the milk.
This will help to incorporate air into the milk and create foam.
Once the milk is frothy, turn off the steam wand and remove the pitcher. Tap the pitcher on the counter to get rid of any large bubbles. Then, pour the milk into your espresso drink and enjoy.
Let’s make our way toward the top of some machines.
8. Bean Hopper
A bean hopper is a container that stores whole coffee beans in an espresso machine. It’s on top of the grinder and made of plastic or metal. The bean hopper has a lid that helps to keep the beans fresh and prevents them from being exposed to air and moisture.
The bean hopper size will vary depending on the model of the espresso machine. Some machines have a small hopper holding a few ounces of beans, while others have a large hopper holding several pounds. The size of the hopper will affect how often you need to refill it.
If you make espresso frequently, you’ll need a larger hopper. Getting a larger one prevents you from having to refill it as often.
Also, consider the material of the hopper. Plastic hoppers are less expensive, but they’re more prone to scratches and cracks than metal hoppers.
This next part is better for making single cups of espresso with a built-in grinder.
9. Bean Doser
A bean doser is a device used to dispense a precise amount of coffee beans into the portafilter of an espresso machine. It’s typically attached to the grinder. And it has a hopper that holds the beans and a mechanism that dispenses them.
You can also set it to dispense a specific weight of beans, which is important for consistency in espresso extraction.
Bean dosers can be a valuable tool for baristas who want to make consistent espresso drinks. They can also help to prevent over- or under-dosing, which can affect the taste of the espresso. Since you won’t have too much or too little coffee grounds.
A built-in grinder reduces the need to constantly transfer beans from a coffee grinder to an espresso machine. Instead, it automatically spits the fine grinds into your portafilter.
These grinders take up less counter space than buying a separate grinder but produce less consistent grinds.
However, they’re excellent for machine integration on super-automatic machines. Usually, you’ll select a drink you want (e.g., cappuccino), and it’ll grind beans to the best size for that drink type.
There are 2 main types of burrs used in espresso machine grinders:
- Flat burrs: 2 flat plates that grind the coffee beans between them.
- Known for producing a more consistent grind size than conical burrs.
- More expensive & noisy.
- Conical burrs: 2 cone-shaped burrs that grind the coffee beans against each other.
- They are less expensive & quieter than flat burrs, but they produce a less consistent grind size.
Here is a table summarizing the key differences between flat and conical burrs for espresso machine grinders:
|Feature||Flat Burrs||Conical Burrs|
|Grind consistency||More consistent||Less consistent|
|Price||More expensive||Less expensive|
|Heat generation||More heat generated||Less heat generated|
Flat burrs are the better choice for espresso machines, as they produce a more consistent grind size. A crucial factor for great-tasting espresso. However, conical burrs can also produce decent results, especially if you are on a budget.
Espresso machines have various parts that are critical for it to run. Some parts—like different pump types—will affect the machine’s price and functionality. Compare the parts’ variations and determine what you’ll need for an espresso machine.
Afterward, look into our home espresso maker buying guide. If you’re looking for a machine for a coffee shop or café, check out our guide for commercial devices.