4 types of Coffee Machine Boiler.
There are 4 types of espresso machine boilers that you might find in domestic & commercial coffee machines, they are as follows;
Thermoblock Boiler.
Single Boiler.
Heat Exchange Boiler.
Dual Boiler or Multi Boiler.
Thermoblock.
These are normally found in lower cost entry level domestic appliances, they consist of an aluminium block with stainless steel pipes spiralling through the block with a heating element embedded inside to heat the water, as the water passes through the spiral it heats along the way creating on demand heated water. They are usually assisted with another heating element to warm the solid block of aluminium to create a more efficient heating system.
These machines have very small holes for the water to spiral through & will easily clog with scale if preventative cleaning is not carried out.
Single Boiler.
These are the next step on the home espresso machine & are used in machines like the Gaggia Classic. The boiler is usually supported with 2 x heating elements on the outside of the vessel & inside you have a boiler that’s full of water rather than the spirals inside of a Thermoblock, this allows the user to create steam so you have the option to foam milk yourself for latte or cappuccinos.
These types of boiler will scale heavily so regular maintenance is required to reduce the risk of boiler failure.
Heat Exchange Boiler.
This system is found on both domestic & commercial coffee machines & can be made of stainless steel or copper. The primary function of this system is to produce freshly heated water for coffee brewing & steam for milk foaming, it achieves this by having a heat exchange chamber inside the steam boiler which keeps water fresh as it passes through a constant thermosyphon out to the group head & back into the heat exchange chamber.
The thermosyphon constantly heats & cools the fresh water, slightly keeping it at a steady brew temperature at the group head, this is key for consistency with brewing temperatures. The steam boiler will be controlled by either a mechanical or electronical pressure stat & will control the heating element when pressure is released from the vessel when steaming milk.
Multi or Dual Boilers.
These are also found in both domestic & commercial coffee machines & sit at the top in terms of performance & price. The multi boiler system does as it says, it has 1 boiler for steam pressure & another for coffee brewing, I refer to these systems as multi boilers as on commercial machines you may find each group head will have its own brew boiler rather than a separate vessel supporting multiple group heads.
In terms of performance multi boiler machines will achieve an very high consistency rate with brewing temperatures as unlike the heat exchange system the water is not cooling when the steam boiler is refilling. The coffee brewing boiler will have a PID controlled boiler that pulse heats every second which keeps temperatures extremely accurate allowing changes to be made to get the best out of every roast.
Naturally with more components & technology the price for multi boiler systems will be significantly higher than single boiler & heat exchange systems, alongside maintenance & servicing costs but if you truly want accuracy to bring the best out of your coffees then multi boiler systems are the best machines for you.
If you have any questions or would like to learn more then call us on 01225436171 or email contact@thecoffeelobby.co.uk
