How Does an Espresso Coffee Machine Work

How Does an Espresso Coffee Machine Work

August 09, 2021

While drinking your morning coffee, you might be wondering how the machine that made the beverages actually work. The nuts and bolts of an espresso machine are actually rather simple, but the components of these machines have a huge impact on the taste of the coffee you drink in the morning.  

The act of producing espresso is significantly influenced by temperature. If the boiler is unable to regulate temperature properly, you may overheat the coffee grounds, resulting in a burnt and bitter drink. If the heating element in your steam wand isn't working properly, you won't be able to obtain a good froth on your cappuccino.

In terms of functionality, an espresso machine brews coffee by forcing pressurized water approaching boiling point through a "puck" of ground coffee and a filter to produce espresso, a thick, concentrated coffee. To make espresso, various machine designs have been developed. A group head and a portafilter are two components shared by several machines. A steam wand on an espresso machine is used to steam and froth liquids (such as milk) for coffee drinks such as cappuccino and caffe latte.

Before we get into how to make an espresso machine work, we need go over all of the key terms you should be familiar with when it comes to espresso and espresso machines. 

Working Components of Espresso Coffee Making Machine

Espresso machines are often made up of the same essential parts that allow you to go from water to a highly caffeinated shot of coffee. There are versions that range from the simple to extremely complicated, but you will most likely find some configuration of these components in the machine you have on your counter. Here are the components:


  1. Control Panel
  2. Water Source and Pump
  3. Heating Chamber or Boiler
  4. Steam Wand
  5. The Grouphead And Porta-Filter

1.Control Panel

Many espresso machine manufacturers include a control panel; the main exception is lever machines, which are hand operated and are not generally available for home usage. Typically, there is a power light that indicates whether the machine is turned on or off.

A temperature control light indicates when the water is hot enough to extract one espresso shot. There may also be a valve to control the flow of steam into the frothing wand.

Some machines may contain pressure and temperature switches or gauges to help adjust the size of the shot. Some machines with built-in grinders contain a dial for adjusting grind size.

2.Water Source and Pump

Every machine requires a water source. The tank on home machines is normally removable, and you fill it by hand to the full water line; commercial and certain higher-end home machines are equipped with the ability to be plumbed into the building's water supply.

The reservoir's water is not heated in its entirety. The pump will transport brewing water from the water tank to the boiler. A bar is a unit of measurement for water pressure that is equivalent to 100,000 newton per meter squared, or one atmosphere. A unit of pressure equal to the mean atmospheric pressure at sea level is referred to as one atmosphere.

The optimal pressure for espresso is 9 to 15 bars, with 9 bars being the lowest pressure required to draw a shot, or around 130 psi, which is four times the pressure in a vehicle tire. The boiler pressure should be approximately 1.5 bar. Pumps are classified into two types: rotary pumps and vibration pumps.

  • To apply pressure, a vibratory pump employs a magnet, piston, and metal coil. When the electricity is turned on, the piston moves at a rate of around 60 pushes per second, pushing the water through the machine. Vibratory pumps are inexpensive and easier to replace. 
  • A rotary pump consists of a tiny motor that spins a sectioned disk. As the disk spins, it presses against the exterior wall of the chamber in which it is placed, producing the required pressure. Water enters the chamber through the main section and is pushed out through the smaller section. Rotary pumps are usually quieter and last longer. 

3.Heating Chamber or Boiler 

Because temperature is so vital in espresso brewing, the boiler is a critical component of the machine. It is a metal chamber with a heating source inside where pressurized water is heated. In these devices, several manufacturers use proportional-integral-derivative (PID) controllers or digital temperature controls. These devices control the heating element's on-off cycles in order to maintain a constant boiler temperature.

The boiler unit's temperature is optimally controlled using PID devices. The ideal brewing temperature is roughly 250 degrees Fahrenheit, just below the boiling point. Boilers contain a one-way valve that prevents brewing water from returning to the machine.

Boilers are classified into three types: single boilers, dual boilers, and heat exchangers.

(a) Single Boiler

These machines operate on a rather simple principle, with only one boiler heating water for the entire brewing process. In one tank, water for both the steamer and the espresso machine is heated.

These machines cannot make espresso shots and steam milk at the same time. These are commonly seen in semi-automatic and low-end automatic equipment.

With these single boiler machines, the water temperature is not as steady.

(b) Dual boiler

The main difference between single and double boilers is that you have two separate tanks boiling water at the same time with two different heating elements (one for the steam boiler and one for pushing through the ground espresso), allowing you to use the steamer and pull a shot of espresso at the same time.

These provide the best temperature stability and are the most effective technique to brew water at a consistent temperature.

(C) Heat Exchanger

A heat exchange boiler uses a large boiler with an isolated part located distant from the heating element. This part will allow for less hot water that is more suited for pushing through ground coffee.

Water is constantly circulated through the isolated portion, into the group heads, and back into the unit as a whole. This type of boiler has a lot of temperature control and allows the machine to do two tasks at once, which is essentially a heat exchange.

4.Steam Wand

The steam wand is utilized when you want to combine your espresso into drinks such as lattes. Its purpose is to steam and froth milk for these drinks. It's linked to the heating chamber. When a valve is turned, steam from the heating chamber is delivered into the milk via the steam wand, making it warm and frothy.

5. Grouphead And Portafilter

The grouphead is the component of the system that permits the pump to send hot, pressurized water to the coffee puck waiting inside the portafilter for brewing.

Inside the group head are two small holes that allow hot water to flow cross-sectionally over the ground coffee inside the portafilter. A portafilter lock, which acts as a pressure switch to adjust boiler pressure, is also included in group heads.

After brewing, a portafilter will lock into the grouphead and may be equipped with a 3-way valve that releases pressure from between the portafilters and group heads, known as a solenoid valve.

If your machine lacks one, you must wait for the pressure to fall after extracting your first espresso before removing the portafilter to avoid a "portafilter sneeze," which is a burst of hot pressurised vapour after removing the portafilter from the grouphead.

The portafilter is a removable part that holds all of the ground coffee in a filter basket. Bottomless and spouted portafilters are the two varieties.

Spouted portafilters contain two spouts beneath the basket that allow espresso to flow from the entire device into your cup.

Bottomless portafilters lack spouts and allow espresso to flow directly from the basket. Bottomless portafilters provide substantially higher-quality espresso shots while also looking more elegant.

How an Espresso Coffee Making Machine Works – Coffee Making Process

Espresso machines are a quick and easy way to acquire a high caffeine content in only a few ounces of coffee. After the water has warmed up, you'll only have to wait around 30 seconds for your shot to be ready.

To get from water to espresso, follow these steps:

  1. You put water in the reservoir and turn the machine on.
  2. The machine begins heating the water in the heating chamber and notifies you when it has reached the ideal temperature.
  3. Remove the portafilter from the machine and fill it with the desired amount of finely ground coffee. You lock the portafilter back into the machine after tamping it down.
  4. You put a little cup beneath the spout of your ready-to-drink coffee to capture the espresso when it's done.
  5. When you put the machine on espresso, it activates a switch within that notifies it when it's time to go.
  6. The pump will turn on and pressurize the water inside the heating chamber until it reaches a pressure of around 220 psi.
  7. The water is forced out of the heating element, past the coffee grounds in the portafilter, and out of the spout into your cup by all of that pressure.

You'll need to do a few extra steps if you want to heat milk to add to your espresso:

  1. Fill a cup halfway with milk and place it under the steam wand, drowning it in the liquid.
  2. When you turn your espresso machine to steam, a valve in the heating chamber opens, allowing steam to escape from the boiling water and into the milk.
  3. If you hold the steam wand near the milk's surface, it will froth up.                                         

Also Read : Difference between espresso machine and coffee makers

 Common Problems with Espresso Machines

With any number of problems that could arise, the following table could help you fix any number of issues that may arise should you happen to encounter them. The solutions provided here are applicable to all espresso machines available on the market. 



Possible Cause


Stop button light on touchpad flashing

Water turned off at mains

Ensure that the water supply is turned on at the mains.

Too much water drawn off at one time from the hot water tap

Using the on/off switch, turn off the machine. Check the water level gauge to make sure the boiler is full. If the touch pad's stop lights flash, repeat the procedure. Turn the on/off switch after the boiler fill light goes out and wait 15-20 minutes for the machine to attain temperature.

Unable to froth milk

Steam pressure is low or slow

Make sure the boiler pressure is set at 1.0 bar. 

Steam nozzle blocked

Remove and clean properly.

Milk quality

Try a fresh batch of milk.

Attempted to re-froth boiled milk

Remove the contents of the milk jug, carefully wash it, and re-froth it with fresh milk.

Cold Coffee

Machine not up to operating temperature

Allow the machine to reach 1.0 bar temperature for 15-20 minutes.

Filter holders not hot

To flush hot water through the filter holders in the brewing group heads, press the jug button for 1 minute, then press the stop button. After the coffee has been brewed, always lock the filter holders into the brewing group heads to maintain temperature.

Cold cups

Ensure to use pre-heated cups whenever needed.

Coffee dispenses too slowly

Blocked brewing group head

On a daily basis, clean the filter holder with the blind filter basket.

Too much coffee in filter holder

Make sure you're using the correct filter basket in the filter holder. For example, for one measure of coffee, use a single filter basket in a single filter holder, and for two measures of coffee, use a double filter basket in a double filter holder.

Check operating pump pressure is at 9 bar

Check that the needle on the left hand side of the gauge reads 9.0 bar after running water through the brewing group head with the filter holder containing coffee.

Grind set too fine

Change grinder setting.

Coffee in filter holder is over compressed (tamped)

Remove the coffee from the filter holder, refill from the grinder, and tamp with the proper pressure.

Coffee dispenses too quickly

Not enough coffee in filter holder

Check that the filter basket in the filter holder is the proper one. i.e. single filter basket in single filter holder for one measure of coffee, double filter basket in double filter holder for two measures of coffee.

Grind set too coarse

Change grinder settings.

Coffee in filter holder is not compressed (tamped) enough

Remove the coffee from the filter holder, refill from the grinder, and tamp with the proper pressure.

Filter holder is difficult to load into brewing group head

Too much coffee on filter holder

Check that the filter basket in the filter holder is the proper one. i.e. single filter basket in single filter holder for one measure of coffee, double filter basket in double filter holder for two measures of coffee.

Coffee leaking from brewing group head / filter holder

Coffee build up on gasket

Clean the filter holder with the blind filter basket on a daily basis.

Leaking from front of the machine under drip tray / grill

Waste pipe / box blocked

Clean up the waste box and waste pipe by removing the drip tray. Using a moist towel, wipe away any coffee deposits, then pour hot water through the box until the flow is clean.

Boiler overflow

Turn on/off switch on machine to off position. 

Leaking from back of machine

Boiler overflow

Turn on/off switch on machine to off position.

Incorrect coffee level in cup

Incorrect dose set on touchpad

The touchpad has to be reset.

Incorrect button on touchpad selected

Check the touchpad diagram to make sure you're using the buttons correctly.

 Is Investing in an Espresso Machine For Your Home Worth It?

If you're the type of person who goes to a specialty coffee shop multiple times a day for a 500 rupees cup of espresso with frothy milk and pumps it into your veins like it's going out of style, home espresso machines might save you a lot of money over time.

If you are concerned about the quality of the water, coffee, milk, and cleanliness used in the preparation of your beverage, an at-home machine might be a suitable choice.

If you're the type of coffee drinker who enjoys a Sunday morning espresso but just has an ordinary cup of joe the rest of the week, an at-home espresso machine might be overkill and a waste of money.

Although having an espresso machine at home can be a lovely experience, it is not for everyone.

Make sure you do your homework and get a machine that is suitable for your needs. Take a look at our suggestions for the top 3 espresso machine for the home.

Final Thoughts

Many individuals all throughout the world benefit from espresso machines. The first thing you could do in the morning is locate your coffee maker and start preparing a delicious cup of coffee. It's just not the same without the caffeine boost.

Even while it may appear that making coffee is simple, your machine is putting in a lot of effort to turn the water you provide into a good hot cup of coffee. You can appreciate them much more now that you understand how they do it.

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