220V Stainless Steel Heating Tube with NTC Sensor for Refrigerator Defrosting Heater BCD-432

Why is the defrosting of a refrigerator necessary?

Some refrigerators are 'Frost free’, others, particularly older refrigerators require occasional manual defrosting.

The component in your fridge that gets cold is called an evaporator. The air in your refrigerator cycles through the evaporator. Heat is absorbed in the evaporator and cold air is expelled.

In most situations people want the contents of their refrigerator to be in the range of 2–5°C (36–41°F). To achieve these temperatures, the evaporator temperature is sometimes cooled to below the freezing point of water, 0°C (32°F).

Air contains water vapour. As the air in your refrigerator comes into contact with the evaporator, the water vapour condenses out of the air and water droplets form on the evaporator.

In fact, everytime you open your fridge, the air from the room enters introducing more water vapour into the fridge.

If the evaporator temperature is above the freezing temperature of water, the condensate that forms on the evaporator will drip down to a drain pan, where it is drained out of the fridge.

However, if the evaporator temperature is below the freezing temperatures of water, the condensate will turn to ice and stick to the evaporator. Over time, an accumulation of ice can form. Eventually this can block the circulation of the cold air through your fridge so while the evaporator is cold, the contents of the fridge are not as cold as you want them to be because the cold air cannot circulate effectively. This is why defrosting is required.

There are different methods of defrosting, of which the simplest is to not run the refrigerator’s compressor. The evaporator temperature rises and the ice starts to melt. Once the ice has melted off the evaporator, your fridge is defrosted and with proper airflow restored, it is able to cool your foodstuffs to your desired temperature again.