Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors
Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Step into the boiler room

Looking at how the heart of any quality espresso machine beats and heats
Whilst other components around the machine are there to either get water in or out of the boiler, most of the functions would not work without a fully working boiler.

Steam for your cappuccinos, hot water for your espresso and americanos, all come via the machines boiler. How the boiler is able multi-task in producing these is really pretty simple,
Firstly, most espresso machine boilers are constructed using copper, which along with being a great thermal conductor, is also corrosion resistant, and flexible enough to withstand the mechanical stresses of the heating up and cooling down cycles.

It is also the most expensive metal to use, so look for a machine that employs copper and you know your in good hands from the manufacture.
There is also multi boiler machines on offer from manufactures, and unless your a total geek about only espresso, then a multi boiler machine is really not required and you will be wasting money thinking you need one.

For the above reason, we will only concentrate on the more popular single boiler machines, and the three production areas of the boiler.

How it works

boiler hot water function

Before we are able to draw any hot water from the boiler, the machine needs to be fully up to temperature by the control from the pressure switch and the element.

The amount of available hot water that the boiler is able to produce is governed by the water level setting on the level probe, as you will see there is a trade off, the more hot water = the less steam capacity available.

When the boiler is fully up to pressure, around 1 bar, you are then able to draw hot water from the tap due to the location of the hot water outlet at the bottom of the boiler and the pressure forcing down from the steam at the top of the boiler.

boiler steam function

Steam is generated inside the top portion of the boiler by heating up the water inside the boiler until the pressure reaches the set point of around 1 bar above atmospheric pressure, this setting is controlled by the pressure switch.

Once the boiler is up to pressure, you are then able to draw this steam off by opening the steam valve on the front of the machine. As you draw more steam from the boiler, the pressure will drop and force the heating cycle to start.

The more power the machine has, i.e. the wattage of the element, the quicker the recovery the boiler is able to achieve.

boiler espresso function

The last task the boiler has to carry out is heat the water up to the correct temperature for your espresso. This is achieved by circulating water around the heat exchanger and group head until you select a drink option.

No water is allowed to flow out of the group head until the solenoid valve is operated which then diverts the heated water through the diffuser and into the portafilter, this is carried out using fresh water from the flow meter.

If the machine has been sat for a while, it is recommended to carry out a quick flush before fixing the portafilter onto the group head, this ensures that there is fresh water inside the heat exchanger and at the correct temperature. 
Terms & Conditions
Copyright © 2020 - Design & Build by Lee Rushton

Web Site Disclaimer

Website Usage Disclaimer

By using the content you find on you agree that the information contained in this website is for your general information and guidance purposes only, faults and operation procedures are generic to all traditional espresso machines and as such can only offer general guidance only.

Espresso machines contain water, steam pressure and electrics, and any reliance you place on information gained is therefore strictly at your own risk. If in any doubt whatsoever you are advised to contact a qualified engineer.

In no event will we be liable for any loss or damage including without limitation, indirect or consequential loss or damage, or any loss or damage whatsoever arising from loss of data or profits arising out of, or in connection with, the use of this website.

Through this website you are able to link to other websites which are not under the control of this site. We have no control over the nature, content and availability of those sites. The inclusion of any links does not necessarily imply a recommendation or endorse the views expressed within them.

While we endeavour to keep the information up to date and correct, we make no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability with respect to the website or the information, products, services, or related graphics contained on the website for any purpose.