How An Electric Oven Works

Video transcript:

Hi I'm Lee from Ransom Spares, to help diagnose problems and replace faulty components on your electric fan assisted oven it is first necessary to understand how it works. In this video we’re going to be using this built in fan assisted Indesit oven to explain each of the main important components and how they work together.

This oven is a single cavity oven which means as well as being a fan assisted oven it also includes the grill as well. Some ovens are twin cavity which simply means that they have a separate oven and grill.

Let’s take a look at all the main components of the oven and how together.


Oven Element, Thermostat, and Fan

First we’ll look at the oven Element, thermostat, and fan.

The main function of an oven is to heat up and cook our food. The heating part of the process is done by an oven element which is normally situated at the rear of the oven. Most ovens nowadays are what’s known as fan assisted. This means that at the same time the oven element is heating up there is also a fan which distributes the hot air around the cavity to ensure even cooking throughout the oven.

Temperature is regulated by the thermostat. To us this is simply a knob which we turn to our desired temperature. But behind the knob is the thermostat switch with a capillary (wire) running from the switch and down in to the cavity of the oven. The capillary is actually a tube with gas inside. As the gas heats up the pressure build up causes small bellows in the thermostat switch to move until they reach the predetermined temperature set by the user. The thermostat will turn the oven element on and off during the cooking cycle as the temperature get to hot or too cool.

The fan should always be on when the thermostat knob is set at anything other than off. There are normally two fans in an oven; the fan that distributes the hot air to aid cooking, and a cooling fan.

The main problems caused by a fault with either of these three components are:


Cooling Fan and Thermal Switch

Next we’ll look at the Cooling Fan and Cooling Fan TOC.

The cooling fan is designed to keep the area between the cavity and the outer casing cool. It is a cylindrical fan and is operated by a Thermal Switch automatically depending on the temperature. As the temperature rises it cause a bi metallic strip inside the TOC to turn the cooling fan on. As the temperature cools the bi metallic strip breaks the contact which turns the cooling fan off. When you finish cooking and turn the oven thermostat off the cooling fan motor should (depending on temperature) still be running and will run for 10 minutes or so until the oven has cooled down sufficiently.

The main problems caused by a fault of either of these components are:

  • Faulty Cooling Fan Motor – Overheating of internal components. Ensure that you can hear the fan still running after the oven thermostat has been turned off. See our video on how to replace the cooling fan motor in an oven.
  • Thermal Switch – Cooling fan motor continues to run even after the oven has cooled down.

Grill Element and Energy Regulator

As with the oven element the grill element is responsible for the heat needed to grill our food. The grill element heat settings are controlled via an energy regulator that sits behind a knob on the oven console. The energy regulator regulates the heat output by the amount of power sent to the grill element which is determined by the user.

 The main problems caused by a fault of either of these components are:


Function Switch

On this oven the function switch is combined with the thermostat. This switch simply enables the user to select which part of the oven they want to use. So if I want to use the grill I need to select the grill on the function switch before it will work.

The main problems caused by a faulty function switch is that the oven may appear not to be working at all, or only some functions may be working.


Door Glass, Door Seal, Door Hinges

Although the door area may not seem as important as the other components we’ve discussed any damage or wear to them will likely lead to poor cooking performance. There will normally be an inner and outer door glass. This is to ensure that the temperature of the outer door doesn’t get too hot. Obviously if there are any breaks or cracks to either door glass then they should be replaced without delay. See our video on how to replace an oven door glass.

The door seal is normally fixed with clips in each corner and should be in good order and free from sagging. If the seal is worn or is sagging then heat will be allowed to escape and cooking performance will be affected. It will also have an effect on the amount of energy your oven is using to maintain the temperature set. Changing an oven door seal is a straightforward job.

Over time the spring within the door hinge can become sprained which will result in the door not closing properly. The only solution to this fault is to replace the oven door hinges. Fortunately replacement is straightforward and we have a video showing you exactly how to do it.

By Lee Gilbert