Copper Vs. Stainless Steel Espresso Machine Boiler (Pros & Cons)

Anyone who cares about their espresso machines cares about the boiler within the machine. The espresso machine boiler is responsible for heating the water used for brewing espresso and for maintaining steady brew water temperatures.

The material that the boiler is made from is important for these processes, which leads to the question, how do copper and stainless steel boilers compare?

Copper espresso machine boilers are very efficient and temperature stable, but they can negatively affect the taste of espresso if they are allowed to degrade. Stainless steel boilers do not degrade easily and produce very clear and good-tasting espresso, but they are inefficient.

The boiler within an espresso machine is one of the most important components of the machine. Without a good boiler or a properly functioning boiler, an espresso machine will be able to brew proper espresso.

For these reasons, it is vital to use the best materials for the boiler. Let’s find out how copper and stainless steel espresso machine boilers compare, as these are two commonly used boiler materials.

Copper Vs. Stainless Steel Espresso Machine Boiler

Closer Look at Copper Espresso Machine Boilers

When the conversation of espresso machine boilers and which material is best for these boilers, copper boilers are often the first to come to mind.

This is because the very first steam-powered espresso machines were typically made from copper and so had boilers made from copper as well. For this reason, many espresso lovers will argue that the best espresso machine boilers are copper because the machine was originally designed that way.

Copper is indeed a good material for espresso machine boilers, but there are some considerations to make regarding copper for this use.

Coffee machine boiler

Copper is a good conductor of temperature and is also a metal that is good at maintaining steady temperatures. This makes copper an excellent material for an espresso machine boiler, as those are two characteristics that contribute to good espresso brewing temperatures, which in turn helps to make espresso better.

However, copper has other properties that are not as good for brewing espresso. This metal tends to tarnish relatively quickly. It must be specially treated to help prevent the copper from degrading quickly within the machine, which happens even more quickly in hot water than it out would otherwise.

The coatings and coverings used to protect the copper from the water and internal temperatures of an espresso machine can be harmful if ingested, and they do not last forever. 

Coffee machine

The coatings themselves eventually wear away within the boiler, exposing the copper to the water, which allows the copper to react with the water. This causes the copper to tarnish and degrade more quickly and also negatively affects the flavor of the water used for brewing.

Copper also degrades quickly in the presence of descaling chemicals that are used to clean modern espresso machines, which is also not ideal.

This means that while copper is a good metal for conducting heat and maintaining steady temperatures, it may also negatively affect the taste and flavor of your espresso. There is a well-documented “copper boiler taste” present in espresso brewed in a machine with this type of boiler.

Having said all of that, let’s consider some of the important pros and cons of copper espresso machine boilers.

Pros And Cons Of Copper Boilers

Coffee machine boiler

Pros

  • Copper boilers are good conductors of heat.
  • Copper boilers hold steady temperatures well.
  • Copper boilers do not degrade quickly.
  • Copper boilers are cheaper to produce than other boiler types.
  • Copper boilers can produce excellent espresso if they are made and treated well.

Cons

  • Copper boilers tarnish over time.
  • Copper boilers can negatively affect the taste of espresso.
  • Copper boilers must be sealed and treated before use in an espresso machine.
  • Copper boilers are susceptible to damage from descaling products.

Closer Look at Stainless Steel Espresso Machine Boilers

Coffee machine boiler

Stainless steel is a less common material for use in espresso machine boilers compared to copper and even other metal such as aluminum. Still, it is becoming popular in some modern espresso machines.

Steel is an instrumental metal for many applications, but many argue that it is not the ideal material for espresso machine boilers. 

The main reason for this is stainless steel holds a lot of thermal mass and is a very dense metal with relatively low heat conductivity. This means that steal requires more heat energy to warm up, it requires more heat energy to maintain a temperature, and it dissipates heat more quickly.

These properties are not considered to be the best characteristics of espresso machine boilers, but there is some good reason to use stainless steel for this purpose as well.

Coffee machine

Stainless steel does not react with water quickly, especially clean and soft water that should be used for brewing with espresso machines. This means that stainless steel lasts significantly longer than other metals when used as a boiler, it does not ever affect the taste of espresso, and it is not negatively affected by descaling chemicals.

This means that the coffee produced by espresso machines is very clear and has no unpleasant flavors whatsoever if brewed correctly.

Stainless steel requires more energy for the use as a boiler and is, therefore, less efficient than copper for this use, but it does not negatively affect the coffee in any way, which is why some coffee lovers prefer espresso machines with stainless steel boilers.

Let’s identify some of the critical pros and cons of stainless steel espresso machine boilers.

Pros And Cons Of Stainless Steel Boilers

Stainless steel boiler

Pros

  • Stainless steel boilers last for a very long time.
  • Stainless steel boilers do not negatively affect the taste of espresso.
  • Stainless steel boilers are not damaged by descaling chemicals.
  • Stainless steel boilers produce very clear espresso.

Cons

  • Stainless steel boilers require a lot of energy to heat up.
  • Stainless steel boilers require a lot of energy to maintain temperature.
  • Stainless steel boilers are not very efficient.
  • Stainless steel boilers are very expensive.

Conclusion

Espresso

After considering all of the characteristics of these two types of boilers used in modern espresso machines, the better of the two for general espresso machines and applications are copper boilers, if the boiler is properly sealed, treated, maintained, and replaced before descaler degrades the copper.

Stainless steel is good for specialized machines that will not be used very often but produce excellent quality espresso that is satisfyingly clear and crisp.