What’s a PID Controller in an Espresso Machine?
Brewing the perfect doppio or ristretto is as much a science as it is an art. The ideal grind size, brew ratio, time, and temperature all play a part in the flavour of the final cup.
While you can use a high-quality burr grinder and scale to maintain the ideal granularity and dose, how do you precisely control the brew temperature? The best home baristas use a PID controller.
Read on to learn more about PID controllers and why you may want to consider getting one.
Brew Temperatures and Espresso
There are three basic variables you should keep in mind to pull the perfect espresso shot (1).
- Brew ratio
- Brew time
- Brew temperature
While both brew time and ratio affect extraction, the brew temperature affects the flavour of your shots.
The brew temperature must remain consistent throughout the extraction to get the most flavorful shots.
This is usually around 93 degrees C, depending on the dose and roast level (1).
Maintaining a consistent water temperature is one of the most important features of an espresso machine because it ensures your shot is neither under nor over-extracted.
Brew Temperature should be used mainly as a way to adjust the flavour of espresso in a machine that keeps temperatures extremely consistent.
Types of Espresso Machine Temperature Control
There are three main ways to regulate brew temperatures within your espresso machine’s group head.
- Mechanical thermostats
- Pressure-based thermostats
- PID controllers
In mechanical thermostats and pressure stats, there is no way to accurately set the temperature of the water passing through the group head. While pressure stats are more precise than mechanical thermostats, temperature variations can vary by as much as ten percent on either the lower or higher end of the spectrum. So, the best espresso machines use a proportional integral derivative, or PID, controller to ensure the temperature remains consistent.
Advantages of a PID Controller
PID controllers ensure the brew temperature remains consistent. So if you set your brew temperature to 93 degrees C, the PID controller, essentially a digital thermostat, will maintain that temperature with only tiny fluctuations throughout preinfusion and extraction.
For an excellent explainer of the different types of thermostats and how they work, check out this video from I Drink Coffee.
If you want to brew commercial-quality espresso, an espresso machine with a PID controller is your best bet, though it will increase the cost of an espresso machine. However, compared with the mechanical pressure stat, the digital PID is a solid state device, which means it has no moving parts to break and will last significantly longer.
The higher price of a PID-equipped espresso machine guarantees you years of consistent espresso shots and an all-around improved coffee experience.
If you’re ready to level up your espresso game, PID controllers give you precise control over the brew temperature for each espresso shot and eliminate any guesswork. Whether you’re brewing a doppio with a Costa Rican dark roast or a ristretto with an Ethiopian medium roast, you’ll pull consistent shots every time.
Yes, you can install a PID controller for your espresso machine if it wasn’t built with one. However, it isn’t easy and may void the warranty. It requires a basic understanding of electrical wiring and programming.
A PID controller works by continuously monitoring the temperature within the boiler and toggling the heating element on and off (2).
You should adjust the brew temperature for espresso shots to account for differences in roast level and dose. A general rule of thumb is to use a lower brew temperature for darker roasts and smaller doses.
- Blake, B. (2019, May 30). Basic Espresso Theory – La Marzocco Home. La Marzocco Home.
- La Marzocco Home. (2015, October 15). A Brief History of the PID – La Marzocco Home. La Marzocco Home. https://home.lamarzoccousa.com/history-of-the-pid/