Heat Exchanger Coffee Machines

The first thing to cover is what a heat exchanger coffee machine actually is. To put it as simply as possible, this is a boiler that transfers heat from one fluid to another without those fluids coming into contact. To visualize this, imagine a pool of water with a tube running through it. The water in the pool will influence the temperature of the water in the tube, and vice versa, despite the tube’s material separating them. These types of boilers are used for thousands of home, commercial, and industrial applications. There is a good chance that you have at least one heat exchanger in your home, whether it’s your water heater, coffee machine, or some other appliance!

But how is this principle applied to an espresso machine, and what does it mean for machine performance?

In an espresso machine, heat exchanger boilers differ from standard boilers because of how they heat and control the water. Where a standard boiler pulls water directly from the boiler to both steam and brew, heat exchangers separate this process. This matters because the difference in water temp for steaming and brewing is over 40 degrees Fahrenheit. That means you’ll have to wait for temperature changes between brewing and steaming. All of this is why the vast majority of commercial machines are a heat exchanger or dual boiler.

In a heat exchanger Coffee Machine, brew water is pulled through a copper pipe that runs through the boiler. These tubes are designed to pull the water at the ideal temperature for brewing, guaranteeing the perfect water temperature every time. This is done by calibrating the pipe’s diameter and size to ensure that water passing through is heated to the correct temp as it runes through the pipe (and therefore through the boiler). Meanwhile, steam is pulled directly from the boiler, allowing you to brew and steam at the same time.

The trade-off here is consistency and specific temps for volume and finer temp control for each process in a dual boiler. These machines are also often more affordable than dual boilers because they just have a lower material cost to produce.

The downside is that it is possible to outrun them in very high volume scenarios, specifically when doing lots of steaming, and brew temps (and because of this, espresso flavour) can be less consistent in these situations as well due to fluctuations in temperature. While this can be true of a dual boiler as well, it’s less likely to run into inconsistencies in brew quality since the brewing is handled by a completely separate boiler and heating element.