All About Oven Controllers

Whether you’re making swords, sterilizing lab equipment, or roasting coffee beans, there are tons of ways to use an oven.

These use-cases all have one thing in common: You have to be able to control the temperature.

That’s where oven controllers come into play. Oven controllers are the point of interface between you and your oven, allowing you to control what temperature the oven heats to (setpoint), how long it stays at that temp (hold time), and often how fast your oven heats up or cools down (ramp rate).

If those terms are new to you, don’t worry! Over the course of this article, you’ll learn about:

• Different types of oven controllers.
• How oven controllers work.
• Which types of oven controllers work best for different types of heat treatments.

Hope you’re ready to get started – we’re just heating up!

Different Types of Oven Controllers

Before getting into how oven controllers work, first, we have to understand the different types of oven controllers. The type of controller you’re using makes a major difference in functionality and control mechanisms, as well as which types of projects your controller’s best suited for.

Below are the different types of oven controllers we’ll be covering:

• Electric oven controllers
• Gas oven controllers
• Manual oven controllers
• Automatic oven controllers
• Open-loop controllers
• Closed-loop controllers
• Single setpoint controllers
• Process controllers

We understand that’s a lot of different types of controllers – and a single oven controller can fall into multiple categories. But once we group them into broader categories, things get a lot less complicated!

Electric Oven Controllers vs Gas Oven Controller

Even if your only experience with oven control is in the kitchen, you’re probably familiar with electric ovens and gas ovens.

Every type of oven controller we’ll be discussing today falls into one of these two categories.

Electric oven controllers control temperature by regulating the amount of electricity that’s sent to the oven elements. These controllers send signals to the oven relays to open and close the circuit.

When the circuit closes, the elements receive more electricity. The oven gets hotter. When the circuit opens, the elements receive less electricity. The oven cools down.

Gas oven controllers, on the other hand, regulate the flow of gas to the burners. More gas means a bigger, hotter flame, causing the oven to heat up. Less gas translates to a smaller flame, resulting in lower oven temperatures.

Manual Oven Controllers vs Automatic Oven Controllers

Both gas oven controllers and electric oven controllers are divided into two distinct categories: manual and automatic.

With manual oven controllers, the temperature of the oven doesn’t change without user input. The controller doesn’t receive any input from the thermocouple or thermostat. It’s up to you to observe the oven temperature and adjust the inputs on the controller to change the oven temperature.

Automatic controllers (also known as digital controllers) do receive input from the thermocouple or thermostat. The controller then uses these inputs to adjust output to the oven, ensuring the oven reaches the right setpoint automatically.

With automatic oven controllers, you can program your oven one time, and the controller will execute the entire firing schedule. With manual controllers, it’s up to you to manually adjust the controller for each segment of the schedule.

Closed-Loop Controllers vs Open-Loop Controllers

Another way to categorize automatic and manual oven controllers is to think of them in terms of closed-loop or open-loop controllers.

Automatic oven controllers are typically closed-loop controllers. That means they monitor the feedback loop between oven temperature and controller output and then make adjustments to ensure the oven reaches the desired temperature.

Manual oven controllers are usually open-loop controllers. Since they don’t receive any information from the thermocouple or thermostat, that feedback loop remains open. It’s up to the user to make manual observations and adjustments to close that loop.

Single Setpoint Controllers vs Process Controllers

Finally, oven controllers can be single setpoint or process controllers. Single setpoint controllers do just what they say: They allow you to program the oven to a single setpoint, and that’s it. Typically, single setpoint controllers don’t include the ability to set ramp rates or hold times.

Process controllers (also known as multi-setpoint controllers) can be preprogrammed with multiple segments with different setpoints, ramp rates, and hold times. From there, the controller automatically executes each segment.

But wait, why would anyone choose to use a single setpoint controller? Simple: There are a lot of applications that don’t require more complex oven controllers – but we’ll be getting to those later on.

How Do Oven Controllers Work?

The specifics for how each of these controllers work change slightly based on the type of controller. So, with that in mind, we’ll be keeping this section high level.

Below are steps for programming an oven controller – as well as what the controller does at each stage:

1. You program your oven controller: First, you program your controller to reach a specific temperature. The input method can change drastically based on the type of controller – from knobs, switches, and dials for manual controllers to advanced touchscreen controls. The most advanced oven controllers (like the ones in the TAP Ecosystem) even let you program your oven remotely from your smartphone or tablet. For manual controllers and single setpoint controllers, programming your controller just involves setting a single setpoint. For automatic and process controllers, you’ll be programming setpoints, ramp rates, and hold times for multiple steps or segments.
2. The oven controller manages outputs to the elements or burners: Once you’ve programmed your firing schedule, the oven controller adjusts the electrical current or gas flow to the oven’s elements or burners, respectively. For closed-loop oven controllers (such as PID controllers), the controller monitors oven temperature and adjusts electric current or gas flow to ensure the oven reaches the temperature it’s programmed to .For open-loop controllers, there are no guarantees the oven will actually reach the temperature it’s set to – so it’s up to you to monitor oven temperature and adjust the inputs on the controller.
3. The oven controller changes outputs to change the oven temperature over time – or it doesn’t: Here, there’s a pretty big discrepancy in how oven controllers function depending on the type of controller you’re using. Automatic controllers and process controllers dynamically adjust the electrical current or gas flow to progress the oven temperature to different setpoints.Manual controllers and single setpoint controllers don’t have this functionality. Instead, these oven controllers just hold the controller at a steady temperature, sometimes with a kiln sitter or limit controller to ensure the oven shuts off after reaching a certain temperature.

Now that you have a pretty good idea about the different types of controllers and how they work, it’s time to explore applications.

Choosing the Right Type of Oven Controller for Your Needs

With all of these options, how do you decide which control method is right for your oven? It depends on what type of oven you have and what types of projects you’re trying to heat treat.

In this section, we’ll be looking at different types of applications and explaining which types of oven controllers will be the right fit.

At Home and Studio Oven Controllers

At-home and studio ovens can be used for a wide variety of projects, which determine the type of oven controller that’s right for your needs. However, compared to industrial oven and lab ovens, these ovens usually don’t require the same level of specificity – so you have more options!

Generally, which type of oven you choose comes down to the level of precision you need, the level of convenience you seek, and how important accessibility is for you or your students:

• Electric Oven Controllers vs Gas Oven Controllers: This just depends on the power source of the type of oven you’re using.
• Manual Oven Controllers vs Automatic Oven Controllers: Manual oven controllers can still work for simplistic firing schedules that don’t require extreme precision – but most artists will still prefer the convenience of an automatic controller. Automatic oven controllers are much easier for you and your students to operate.
• Open-Loop vs Closed-Loop Controllers: Again, this comes down to precision and convenience. Crafts like bladesmithing and knifemaking have millennia-old traditions and can technically be executed without even using a thermometer! That said, all but the most dedicated artisanal craftspeople benefit from the precision of closed-loop controllers.
• Single Setpoint vs Process Controllers: For most heat treat processes involving metal, single setpoint controllers provide all the functionality you need. However, for glass annealing ovens, you will 100% need a process controller. But even for firings that only require a single setpoint, process controllers can add convenient features like remote oven start.

Industrial Ovens

For most industrial ovens, such as those used for manufacturing or waste processing, precision and consistency are key. As a result, automatic, closed-loop oven controllers are best suited for most industrial applications.

Features like temperature monitoring and diagnostics for troubleshooting avoid costly downtime or firing errors. That said, manual oven controllers haven’t been entirely phased out and are still used in some factories or waste processing plants.

Whether industrial ovens require single setpoint or process controllers very much depends on what they’re used for. For instance, waste processing ovens usually only need a single setpoint controller, while process controllers are required for manufacturing ceramic or glass products.

Laboratory Ovens

For laboratory ovens, precision is of the utmost importance. Closed-loop controllers are better suited for these applications. Whether lab oven controllers should be automatic or manual, single setpoint or process, depends on what they’re used for.

If you’re just using a lab oven to keep samples at a set temperature or to sterilize equipment, a single setpoint controller (or sometimes a manual controller) might be all you need. However, if you need to freeze or thaw samples or dry, cure, or anneal polymers, you’ll probably need an automatic process controller.

Bladesmithing and Knifemaking Ovens

For bladesmithing and knifemaking, cooling often happens outside of your heat treat oven. That means that a single setpoint controller like TAP&Go might be all you need. Single setpoint controllers are often less expensive and extremely simple to use.

For these applications, manual controllers are still viable options – but they’re less convenient.

If precision is important to you, we recommend using a closed-loop controller. While process controllers may not be necessary, they can add an additional level of convenience – like the ability to preheat your oven remotely.

Jewelry Making Ovens

Whether you’re making jewelry from metal clay or polymer clay, most jewelry ovens only need to achieve a single setpoint for a single hold time. Thus, single setpoint controllers are really all you need. Even manual oven controllers can often do the job at the cost of convenience and more exposure to user error.

That said, closed-loop controllers add additional precision to jewelry making.

Glass Annealing Ovens

For glass annealing ovens, you have to be able to achieve specific setpoints and adhere to precise ramp rates. Given these specifications, manual oven controllers and single setpoint controllers will not be suitable for these applications.

For glass annealing, you’ll need an automatic process controller that’s preferably closed-loop.

Power Your Electric Oven with the Most Advanced Oven Controllers

No matter what type of electric oven you have – or what projects you do with it – the TAP Ecosystem has you covered!

All of our oven controllers are dedicated to two main principles: precision and ease of use. To us, that means PID-driven control algorithms, intuitive touchscreen controls, unlimited firing schedules, and remote oven monitoring and control through TAP Kiln Control Mobile.

Below are different options we offer for industrial, laboratory, at home, and studio ovens:

• TAP II Oven Controller: For single zone ovens, TAP II brings simplicity and ease of use to even the most complex heat treating processes. TAP II is an automatic process controller that’s suited for at home, studio, lab, and industrial applications.
• TAP II Pro Multi-Zone Oven Controller: TAP II Pro is our flagship multi-zone kiln controller that provides precise, intuitive automatic oven control for up to three different temperature zones. Other features include an exclusive Cone Fire Mode for bisque firing schedules and a more responsive capacitive touchscreen with better viewing angles.
• TAP&Go Single Setpoint Controller: Designed specifically for heat treat projects and single setpoint firing schedules, TAP&Go provides an intuitive, cost-effective option that’s perfect for knifemaking or crafting jewelry.
• TAP Micro Oven Controller: Looking for a cost-effective, entry-level process controller? TAP Micro might just provide the functionality you need, as well as the convenience of remote temperature monitoring and control through your smartphone or tablet.
• TAP Monitor Digital Pyrometer & Limit Controller: Even if you use a manual or open-loop oven controller, you can pair TAP Monitor with your oven for precise remote temperature readouts and push notification alerts to your smartphone or tablet.

Explore the TAP Ecosystem to find your next oven control solution – whether you’re building a new oven from scratch or shopping for conversion kits or standalone oven controllers to upgrade your current build.

If you’re looking to buy an 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