Cooker & Oven selector switch and thermostat regulator how they work

 

Understanding the Difference Between a Switch and a Regulator

Many of our customers use the terms ‘switch’ and ‘regulator’ interchangeably when talking about cooker controls. While both parts control the heat of your hob or oven elements, they function in fundamentally different ways. Understanding this difference is crucial for diagnosing a fault and ordering the correct replacement part. Let’s break it down.

 

The Cooker Control Switch: A Mechanical Master

At its core, a cooker control switch is a straightforward mechanical device. Think of it as a set of pre-programmed light switches all operated by a single knob.

• How it Works: When you turn the control knob, you are rotating a component called a camshaft. This shaft has a series of shaped lobes (cams). As the shaft turns, these cams physically push against brass contact arms, either opening or closing electrical circuits.

• Function: By closing different combinations of contacts, the switch sends power to various sections of a heating element or hotplate. For example, setting ‘1’ might power a small inner coil, while setting ‘3’ might power both the inner and an outer coil, thus increasing the heat output. The heat levels are fixed and determined by the physical design of the cams.

• Variations: You’ll notice in our video that even for the same cooker, switches can look slightly different. One might have an extra wiring harness to support a ‘piggyback’ thermostat for the main oven. The shape, size, and cam profiles are unique to the specific appliance they were designed for.

A switch provides a set number of fixed heat levels by mechanically completing different circuits. It doesn’t sense temperature.

 

The Regulator or the Smart Controller

A regulator, often known by the brand name ‘Simmerstat’, is a more sophisticated component. It doesn’t just switch circuits on and off; it regulates the power flow over time to achieve a variable temperature.

• How it Works: The magic inside a regulator is a bi-metallic strip. This is a small strip made of two different metals bonded together. When electricity flows through a small heater next to this strip, it heats up and bends, breaking the electrical contact to the main heating element. As it cools down, it straightens out, reconnects the circuit, and the element heats up again.

• Function: The control knob on the front adjusts the distance the strip needs to bend before it breaks the contact. On a low setting, the strip breaks the circuit quickly, meaning the element is off more than it is on. On a high setting, the strip has to get much hotter to bend far enough, so the element stays on for longer periods. This pulsing of power gives you fine control over the cooking temperature.

• Safety: Some elements controlled by regulators, especially ceramic hob elements, have a secondary safety cutout. This is often a thin metal rod in a glass tube that expands with heat. If the regulator fails and the element overheats, this rod expands and pushes a switch to cut the power, preventing damage.

A regulator controls temperature by cycling the power to the element on and off. The higher the setting, the longer the ‘on’ cycle.

 

Why Getting the Right Part is Critical

As you can see, these two components are not interchangeable. Fitting a switch where a regulator should be (or vice-versa) will result in incorrect and potentially dangerous operation. Even two switches that look identical can have different cam profiles or terminal layouts.

The only way to be certain you have the correct part is to use your appliance’s model number. You can type this into the search bar on our website to see a full list of compatible spares for your specific machine.

 

We hope this guide has cleared up the confusion between cooker switches and regulators. For all the spares and tools you need for this and any other appliance repair, head over to how-to-repair.com. Your support allows us to keep making these free, helpful guides.

If you have any questions about any of your appliances, please provide your brand, full model number which is written on the identification label, and a detailed description of the issue. Please visit our Contact Us page and make sure you fill out the request for what your problem is. A video shoot of the problem would be perfect as well.

If you found this guide helpful, consider supporting us by clicking on the Buy Paul a Beer link to help us continue making repair videos and guides.