If you’re shopping for a new kiln or oven or exploring controller upgrades, you might have asked yourself: “Do I need a PID temperature controller – and what does that even mean?”
You’ve probably seen those three letters show up so often in your search that it’d be easy to write them off as marketing jargon.
That’d be a mistake.
When it comes to kilns, ovens, or industrial furnaces, there are two key temperatures:
- The temperature (or setpoint) you program into your temperature controller.
- The temperature your firing chamber actually heats to.
In a perfect world, those two temperatures would always line up exactly.
In real-world applications, that’s not always the case: Environmental temperature, resistance in your kiln elements, or even just opening your oven door mid-firing can all cause a disconnect between your programmed setpoints and your real-world firing temperatures.
That’s where a PID temperature controller comes into play…
What Is a PID Temperature Controller?
PID temperature controllers use a closed-loop digital feedback system to monitor the actual temperature of your kiln or application. Instead of just sending instructions to your kiln’s elements to heat up to a defined setpoint, PID controllers receive real-time temperature data from your thermocouple.
The controller uses that data to dynamically adjust outputs to compensate for detected discrepancies.
This ensures your oven adheres as closely to the programmed firing schedule as possible – with fast response, minimal overshoot, and greater precision.
The 3 Components of PID: “Proportional Integral Derivative”
“PID” is an acronym: It stands for “Proportional Integral Derivative.” PID temperature controllers use a mathematical formula to calculate the difference between input temperature and the current temperature of the application, as well as predict future discrepancies.
The controller’s algorithm helps it predict how much power to use to mitigate any variance between expected temperature and actual temperature – for the past, present, and future.
Let’s break down what each of these letters stands for:
- Proportional (P): Adjustments based on current variance between programmed setpoint and actual temperature. The controller detects variance between programmed setpoint and actual temperature and adjusts input proportionally to close the gap – often leaving a minor offset where the actual temperature settles just below the setpoint.
- Integral (I): Adjustment based on past variance between programmed setpoint and actual temperature. To bridge this offset, the controller tracks accumulated variance and steadily adjusts outputs to compensate for the remaining offset.
- Derivative (D): Adjustments based on predicted future variance between programmed setpoint and actual temperature. Based on past and present variance, the controller compensates for predicted future variance to prevent overshoot or wide swings in temperature.
Think of it like this: Pretend you’re cooking a turkey in the oven. You heat your oven to a specific temperature. But then you use a thermometer to verify your turkey cooked to the correct temperature. If it didn’t reach the right temperature, you put it back in the oven for longer or adjust the setpoint.
Then, the next time you cook a turkey in this oven, you’ll use this past data to adjust your inputs for more consistency and precision.
The difference is that a PID temperature controller does all of this automatically in real-time– with minimal lag time between output and input adjustments.
What Are the Benefits of PID Temperature Control?
As you can imagine, this technology has a ton of benefits. In fact, for many artists, craftspeople, or manufacturers, PID control algorithms are non-negotiable.
After all, imagine spending 13 or 14 hours firing bisque or fusing glass just to have your project fail because your kiln didn’t reach the right temperature. For individuals, this is frustrating. For industrial processes and manufacturing, this kind of variance can be extremely costly.
Below are benefits of using a PID controller:
- Faster Response: By making adjustments based on actual temperature, PID temperature controllers reach programmed setpoints faster.
- Higher Accuracy: PID temperature controllers minimize errors, offset, and overshoot – for better accuracy and precision.
- More Consistency: By compensating for detected variance, PID controllers minimize batch variations or unexpected results.
- Fewer Errors: By regulating temperature throughout the firing process, PID controllers help minimize overfiring, underfiring, or other unexpected results.
Regardless of what medium you work in, heat treatment is equal parts art and science. PID temperature controllers help ensure that your projects reach the exact temperature they need to fire successfully and have the right properties.
Applications of PID Temperature Controllers
PID temperature controllers are used in a wide range of applications. In fact, anywhere that temperature is used to control outcomes, PID algorithms help ensure those outcomes are more accurate, precise, and consistent.
Applications include:
Artistic Applications
- Heat treatment
- Kiln formed glass
- Ceramic firing
- Knifemaking
- Making jewelry
- Candle making
- Aromatherapy
Industrial Applications
- ICS control systems
- Laboratory ovens
- Manufacturing
- Machining
- Plastic molding
- Coffee roasting
- Waste processing
- Chemical processing & storage
- Food processing
PID Controllers for Other Applications
PID controllers aren’t just limited to temperature control. In fact, different types of PID controllers are used to manage a variety of process variables. These include: pressure, flow, level, composition, speed, and motion.
In these applications, PID controllers work by the same set of principles: They measure actual conditions against programmed setpoints and compensate for any discrepancies.
But for the sake of this article, let’s stick to what we know: controlling temperature!
Single Zone vs. Multi-Zone PID Temperature Controllers
PID temperature controllers can be single zone or multi-zone. Basically, a single zone PID controller heats up your entire kiln or heat treat oven to a single, uniform temperature.
A multi-zone PID temperature controller, on the other hand, can simultaneously heat or cool different zones of your kiln or oven to different temperatures. Pretty cool, right? This allows you to fire multiple projects simultaneously or get more granular on your temperature control for a single project.
Are TAP Kiln Controllers PID?
Yes, every kiln controller in the TAP lineup has PID control algorithms.
In fact, TAP stands for “Temperature Automation by Proportional Integral Derivative.”
(It also makes for a cool double entendre, mimicking the sound it makes when you tap on your controller’s easy-to-use touchscreen).
From the very beginning, we designed TAP to accomplish two main objectives:
- Provide a simple, intuitive user experience so that anyone can use TAP to power their projects.
- Create the most precise, advanced kiln controller – with unlimited firing schedules, remote monitoring and control, advanced diagnostics, and more.
Building our platform around PID temperature control algorithms was an essential part of accomplishing our second objective!
Power Your Kiln With TAP
You don’t have to choose between precision and ease of use. Our lineup of PID temperature controllers is designed to give you both!
We invite you to streamline your firing experience with more convenience, flexibility, and precision. Check out the industry’s most advanced, easy-to-use controllers with TAP II for single zone kilns, TAP II Pro for multi-zone kilns, or TAP&Go for single setpoint heat treat applications.
All of our controllers and digital pyrometers pair with TAP Kiln Control Mobile – the industry’s highest-rated mobile app – to let you monitor projects on-the-go, receive real-time push notifications, or make real-time schedule adjustments.
Check out the TAP Ecosystem for all of your temperature controller needs! Or, if you’re looking to buy a kiln or heat treat oven where TAP comes included, check out one of our partners below:
- Evenheat
- Hot Shot Oven & Kiln
- Paragon Kilns
- Mobile Glassblowing Studios, LLC
- Jen-Ken Kilns
- Kiln Frog
- Sheffield Pottery
- Delphi Glass
PID Temperature Controller FAQ
How is a PID controller different from an on-off controller?
On-off temperature controllers are the most basic feedback control system. As the name implies, on-off controllers only have two states: fully ON or fully OFF.
These controllers only base their power outputs off a single setpoint. If the application heats up past that setpoint, the controller cuts power to let the application cool down. If the application cools down below the desired setpoint, the controller activates to send more power and heat up the application.
This causes actual temperature to constantly oscillate between too hot and too cold – though generally close enough to the desired setpoint. On-off controllers are low cost and work for applications like home thermostats, water heaters, or refrigerators where precision and exactness aren’t particularly important.
A PID controller, on the other hand, constantly measures and predicts variance to make gradual adjustments. This allows PID temperature controllers to hold temperature as close to the setpoint as possible – for more stability and a scientific level of accuracy.
Do TAP Kiln Controllers provide automatic PID tuning?
Yes, TAP Temperature Controllers self-tune to provide consistent, precise PID control. Out-the-box, TAP provides a calibration accuracy of ±.01% of span and ±.1°C at calibrated ambient temperature.
The vast majority of users never have to adjust their PID settings. However, if you need to adjust PID tuning, you can contact your kiln manufacturer to unlock them in your Advanced Settings.
Please note: We only recommend this for extremely advanced users or for industrial applications – there’s a reason we don’t provide access to Advanced Settings by default!
What are different types of PID temperature controllers?
PID is just one element of temperature controller performance. It describes how precise the controller is, but it doesn’t dictate what type of functionality the controller provides.
PID control algorithms can be integrated with different types of temperature controllers, such as:
- Process Controllers: These controllers automatically adjust temperatures to execute complete firing schedules with no or very little user involvement. These controllers can be single zone or multi-zone.
- Single Zone Controllers: Single zone PID controllers like the TAP II use a single thermocouple to drive the entire kiln or oven to a uniform temperature for each stage of the firing schedule.
- Multi-Zone Controllers: Multi-zone PID temperature controllers like the TAP II Pro receive inputs from multiple thermocouples to drive outputs to multiple elements – to heat different zones of the kiln or oven to different temperatures.
- Single Setpoint Controllers: Single setpoint controllers like TAP&Go simply heat the kiln or heat treat oven to a single setpoint, versus progressing through multiple setpoints and ramp rates. This simplified functionality is typically used for heat treat, electric furnace controls, food ovens, and laboratory ovens.
- Safety Limit Controllers: Safety limit controllers like TAP Monitor don’t execute firing schedules at all. Instead, they enhance kiln safety by ensuring your kiln shuts off if it exceeds a specified temperature – even if your primary relay fails.
If you’re shopping for temperature controllers, we strongly recommend investing in one that has PID technology – regardless of your control needs.
When was the PID temperature controller invented?
For consumers, PID temperature controllers are a relatively new technology. In the mid-1980s, the first automatic (or digital) kiln controllers were invented. Unlike kiln sitters and manual kiln controllers which required constant user intervention and could only control for max temperature, these controllers could make adjustments automatically based on feedback from the kiln.
However, like other advancements in heat treat, this technology didn’t appear overnight. Below are some key dates in the development of PID controllers:
- 17th Century: In the 1600s, Dutch scientist Christiaan Huygens invented the centrifugal governor, which used Proportional (P) feedback to regulate the distance and pressure between grinding stones in windmills and water wheels. By the mid-1700s, this technology had become widely adopted.
- 1788: With the invention of the steam engine, James Watt expanded on this technology to control speed and regulate admission of steam into the engine.
- 19th Century: Governor technology continued to evolve to keep up with increasing engine speed. These governors continued to rely on mechanical regulation based on Proportional (P) (and rudimentary Integral (I)) feedback but became increasingly smooth and accurate, incorporating technology like springs, water turbines, and dampeners by the late 1800s.
- 1911: Inventor Elmer Sperry designed the first true PID controller – which used gyroscopic technology to make adjustments based on Proportional (P), Integral (I), and Derivative (D) feedback – to automatically steer ships.
- 1922: Russian-American engineer Nicolas Minorsky analyzed Sperry’s invention to formalize the theory behind PID and outline the mathematical principles.
- 1931: The development of pneumatic devices allowed for more accurate sensors and simulations, and Minorsky’s hypothetical work became a reality. In 1931, the first general purpose PID controller was developed by the Foxboro Company.
- Mid-1930s: PID control technology exploded, with over 600 control companies applying this technology to different industrial process variables. Major early players included the Taylor Instrument Company, Bailey, Brown, Fisher & Porter, Honeywell, Kent, Leeds & Northrup, Siemens, and Yokogawa (if you follow temperature control technology, you’ve probably heard a few of these names!).
- 1942: These early analog PID controllers relied on manual tuning to maintain accuracy. In 1942, John Ziegler and Nathaniel Nichols published “Optimum Settings for Automatic Controllers,” the first widespread guide for self-guided PID tuning.
- Post-World War II: The second world war led to rapid advancements in control technologies like fire-control systems, autopilots for ships and planes, self-guided torpedoes, and long-distance communication. After the war, these advancements made their way to commercial industry and consumer technology.
- Late 1950s to 1980s: The Cold War and the space race led to significant strides in PID control technology. PID temperature control shifted away from pneumatic devices to computer control.
- Mid-1980s: The first digital temperature controllers hit the market, and PID temperature controllers become widely available to consumers.
- 2015 to 2016: SDS Industries revolutionized the temperature control industry by being the first company to pair PID control algorithms with touchscreen controls and remote kiln control technology.
Whew! How’s that for a history lesson? If you want to learn more about kiln history, check out the TAP IN Blog!
