Thermoblock vs thermocoil vs boiler heating systems in espresso machines

I am selecting an espresso machine. I am seeing that machines come with thermoblocks, thermocoils and boilers. Which heating system is better? What is the difference between thermoblock vs thermocoil vs boiler?

Owly Choice reader Andrew

In short, a boiler is the best heating system which ensures perfect temperature consistency throughout the brewing process. It is also the most expensive system, which is used in most commercial espresso machines. A thermocoil is much better than a thermoblock. It heats up water quickly and more evenly. It is also less susceptible to problems. Last but not least, a thermoblock is the most basic heating system prevalent in many inexpensive coffee machines. It heats water quickly, but may sometimes fail to deliver consistent water temperatures.

In more recent years, the manufacturers have started to add PIDs, or proporitonal-integral derivatives, to give coffee baristas even more confidence in consistency of perfect brewing temperatures, regardless of the heating system.

Thermoblock vs thermocoil vs boiler

What thermoblock is in espresso machines

A thermoblock is a heating element that heats up water for brewing and steaming on demand.

It pulls a specific amount of water from the reservoir. That water consequently passes through a multi-piece block of metal. As the water travels through that piece, it warms up for brewing and steaming. Because only small amounts of water run through the block at any given second, a thermoblock is able to fairly quickly heat up water to brew a shot of espresso.

There are many types of thermoblocks, but they all work very similarly. Some of them are made of high grade materials, which thus make them more durable, but there are some made of less sophisticated materials. Because of their structure and design, thermoblocks are more commonplace in home espresso machines.

There are 2 main benefits of thermoblocks: affordability and speed. Since thermoblocks are not terribly complex heating systems, they are rather inexpensive. Therefore, espresso machines with thermoblocks tend to be less expensive. Further, thermoblocks heat up water rather fast. They only pull and heat up water that is needed for a specific beverage, so the process is rather quick.

On the other hand, there are a couple of disadvantages of thermoblocks: insufficient durability and lack of temperature  consistency. Unlike thermocoils, thermoblocks are made of two separate parts that are wielded together. Those two jointed pieces may, overtime, become more prone to leaking and breaking.

Furthermore, thermoblocks can lose heat pretty quickly. While water might be hot enough for brewing, there might not be enough heat for proper steam and milk frothing. Therefore, the temperatures might not be as consistent as it is desirable for espresso-based beverages.

We are seeing that thermoblocks are gradually replaced by thermocoils.

What thermocoil is in espresso machines

A thermocoil functions like a thermoblock. It also heats up water on demand for brewing and steaming.

The main difference in thermoblock vs thermocoil is that a thermocoil uses a single tube, instead of a multi-piece block of metal. The tubes are typically made of copper and other metals, depending on a manufacturer.

In a thermocoil, only small amounts of water pass through the tubes at any given second. This allows all the water to be evenly exposed to the heating element and boil up. Because of the more thorough circular movement of the water in the chamber, the water is generally more consistent in temperature.

There are 2 main benefits of thermoblocks: more consistent results and durability. By design, thermocoils do a much better job in delivering consistently hot water for brewing and steaming. Because the water passes through the heating element in a circular movement, all drops of water are evenly exposed to the heating element. Further, thermocoils are much more durable. Unlike thermoblocks, which can leak, thermocoils are made with one cohesive element. Therefore, they are unlikely to leak or break, even after many uses.

In fact, we see that thermocoils gradually replace thermoblocks in home espresso machines.

On the other hand, there are a couple of disadvantages of thermoblocks: cannot pull two espressos at at a time and price. While a bit faster than thermoblocks, thermocoils are also prone to losing heat pretty quickly. After one espresso is pulled, a thermocoil needs time to re-heat for another round of espresso and steaming. Additionally, because thermocoils are a bit more complex (and they yield much better results), the machines with thermocoils tend to be more expensive.

What boiler is in espresso machines

A boiler-based heating system is typically the best in class. It efficiently heats large quantities of water at a time, which it then stores for usage.

The founding father of a boiler-based heating system is Archille Gaggia. In 1920s, his machines were the first one to use boilers. Because of their perfect design right from the get-go, Gaggia machines have only improved since 1920s. Coffee lovers can buy Gaggia machines with boilers up to this day.

There are two types of boiler-based heating systems: a dual boiler system and a single boiler system.

The best and most expensive espresso machines come with dual boilers (one boiler for brewing coffee and one for steaming the milk). This shortens the time between brews considerably, and ensures appropriately consistent temperatures for brewing and steaming.

However, there are some machines that come with a single boiler. The single boiler heating systems are not as efficient as thermocoils. Further, single boilers produce hot water for both brewing and steaming. These machines require additional attention to switch the lever between brewing and steaming. Forgetting to do so may result in overly hot water going through the grounds, or water too cool to generate the steam.

PROs and CONs of boilers in espresso machines

Overall, there are many advantages of boiler-based heating systems in espresso machines: temperature consistency and control, extreme durability, and volume.

Unlike single boilers, double boiler systems do a phenomenal job in offering temperature control and delivering consistently perfect temperatures. Because one boiler is used for brewing and another for steaming, a barista can properly adjust temperatures.

Second, boilers are high quality and much more durable than thermoblocks and thermocoils. Espresso machines with boilers are typically high-grade and serve for professional baristas for many years.

Last but not least, boiler-based espresso machines can deliver hot water at all times, irrespective of volume. While thermoblocks and thermocoils need time to heat up between the pulls, boiler-based espresso machines are ready-to-go at all times. They are particularly useful in coffee shops where consumers order espresso-based beverages on an ongoing basis.

However, boilers also have some disadvantages that you need to think about: price and insufficient energy efficiency. Because boilers are typically very complex in structure and design, espresso machines with boilers tend to be very expensive. While consumers can purchase espresso machines with boilers under $500, these machines typically sell for north of +$500. They are great for true coffee aficionados and professional baristas. Furthermore, boilers heat water in boilers at all times. Therefore, there’s very little energy efficiency. The machine is constantly on to continuously heat water. If the machine is just turned on, it takes about 10-15 minutes for the machine to be ready.

Owly’s conclusion

A heating system is an instrumental part of espresso machine, which determines the end quality of coffee. There are small differences between thermoblock vs thermocoil, and even larger differences between them and boilers.

Thermocoils are much more superior to thermoblocks. They are more durable, and deliver better results overall. Thermocoils ensure that water is consistently hot for brewing and steaming.

On the other hand, boilers are much better than thermocoils and thermoblocks combined, but they are the best fit for advanced coffee aficionados and professional baristas.

Should you choose a thermoblock, thermocoil or boiler in your espresso machine? Well, the answer to this depends on what you would like to accomplish. Thermoblock can be a perfectly fine option for most users. They brew delicious coffee and are affordable. Thermocoils can be a great fit for more advanced coffee lovers who want to have more ownership and flexibility in the brewing process. These individuals typically notice the nuances of temperature on coffee extraction. Last but not least, boilers are for very advanced coffee aficionados and professional coffee baristas.

What do you think?

What do you think about thermoblock vs thermocoil and boiler? Which heating system does your espresso machine have? Which heating system is best for your needs?

Let us know in the comments!