What is PID on a coffee machine?

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If you’re an experienced coffee brewer, or have done your research while trying to find an appropriate espresso machine for your home, you will understand the importance of temperature when it comes to effectively extracting the desired flavours found in your favourite coffee beans.

Over the last two decades, quality-focused espresso machine manufacturers have integrated temperature control technology into their machinery by using a PID controller to meet the high demands of modern coffee lovers.

In this article, we cover the ins and outs of PIDs to help you understand what to look for when purchasing or upgrading your coffee machine.

A brief history of the PID

The first PID found on an espresso machine was in the late 1980s, but it wasn’t used in the same way as in today’s espresso machines. It was a fairly basic device in comparison.

Jumping forward to Seattle in the mid-1990s, we find David Schomer, founder of Espresso Vivace, working closely with the world-famous Italian espresso machine manufacturer, La Marzocco.

Schomer, among other coffee geeks at the time, became fixated on the effects that temperature had on espresso and started searching for a higher level of temperature control in the brewing process.

One of the individuals Schomer inspired was Andy Schecter, who ran a high-quality tofu manufacturing business in New York, where they were already using PID systems to control the temperature in production.

In the early 2000s, Schecter managed to successfully ‘hack’ his home espresso machine with a PID, giving the Rancilio Silvia precise temperature consistency.

A few weeks later, Schomer revealed a La Marzocco Linea with a PID installed (among other upgrades), making it the first commercial espresso machine to have PID temperature stability.

PID is now a staple feature on modern commercial espresso machines, allowing the barista a greater level of temperature control that has dramatically improved the standard of coffee found in cafes around the world.

Along with the growing population of dedicated home coffee brewers, the increased demand for more precision focused features on home espresso machines has made PID temperature control become a regular part of home espresso machines.

What does a PID controller do?

A PID (proportional-integral-derivative) controller, also known as a ‘three-term controller’, uses a PID algorithm that is used in numerous industries requiring specific setpoints (SP) to be monitored and controlled.

Before the use of PID control, classic thermostat and pressure stat systems would work by feeding power to the heating element that would heat up until it hit the set temperature then turn themselves off to cool down if it exceeds the desired temperature. It would then power on again when the temperature drops below, and so on, in an attempt to stay at the same temperature.

PIDs work as an accurate way of controlling water temperature in a boiler by turning the heating element off and on in much smaller bursts.

Described as ‘blips’, the PID makes micro-adjustments, resulting in more stable and accurate water temperature through the group head when making a brew.

With the noticeable positive effects of a consistent boiler temperature, PID controllers have become a staple feature on many espresso machines, helping to improve the quality and consistency of coffee extraction.

Why is a PID necessary?

Brewing

Using an espresso machine with a PID controller can drastically raise the quality of a cup of coffee when making a shot of espresso.

The flavours in coffee extract at different temperatures and pressure levels, so without consistency in an espresso machine boiler, it makes it difficult to recreate your previous brew.

Steam pressure

Steam pressure is also delivered at a more consistent level when compared to an espresso machine without a control system.

By keeping the hot water at a constant temperature, the steam will push through the valve at a more consistent pressure, which is essential when wanting to produce finely textured milk for a latte, flat white, or cappuccino.

Adding a PID controller to an espresso machine.

Espresso machines that use a conventional thermostat to control temperature are less accurate than those with PID controlled water temperature, but retrofitting a temperature stability system is an option for those whose machines did not come with one.

Two of the most well known espresso machine manufacturers, Gaggia and Rancillio, whose entry level espresso machines are regarded as some of the best on the market, have both had PID controllers developed that can be added to their boilers as an upgrade to give users more control when using one of their home espresso machines.

The thought of adding a PID controller to an espresso machine yourself may be quite daunting, with there being so many precision built parts hidden by the machine’s casing.

However, there are numerous YouTube tutorials that walk through the process of adding a PID to an espresso machine, explaining how to identify and disconnect the thermostat, then attach the controller.

Your chances of successfully completing the task will, however, benefit from some level of electrical understanding, as well as some knowledge of how an espresso machine works.

The added benefits when fitting a PID to the boiler in an espresso machine can give users access to pre-infusion and accurate temperature adjustments.

Modern espresso machines

Most modern espresso machines will come fully equipped with a PID, and will usually have it listed as a feature in the product’s description and manual.

Generally, they will be preset to deliver a consistent temperature of around 92c for brewing, and strong steam pressure for milk frothing.

Some more advanced machines will give you full control over the boiler’s temperature settings, allowing you to adjust the temperature to get the most out of the beans you are using to make a shot of espresso.

Lighter roasted coffee beans, which have become favoured by modern coffee lovers as they hold a higher level of complexity in flavour, work best with higher temperatures that help to balance out the natural acidity of the coffee.

Conclusion

Whether working with manufacturer pre-set or adjustable temperatures, PID has revolutionised the way we taste espresso.

With greater levels of consistency in the temperature when brewing, we have been able to achieve more control in extracting the exact flavours we are looking for, which really adds to the experience of brewing amazing coffee.