What is No Frost?

No Frost is a cooling technology in which frost and frost do not form in the working chamber of the refrigerator. Hence the name, meaning "no hoarfrost" or "no hoarfrost". But in reality, this name only partially reflects the essence of the system and slightly misleads users who are sure that this technology is synonymous with automatic defrost.

Just frost and ice in refrigerators with No Frost is formed abound and even more than in models without this technology. The elements simply covered with hoarfrost are moved outside the working compartment. Opening the door of the unit, we do not see a single hint of icing or condensation, not to mention the so-called ice "coat" on the walls or shelves.

No Frost - no frost on the walls of the working chambers.

Actually, to “pull out” all the moisture (it turns into frost when cooled), No Frost necessarily provides for air circulation, that is, there is a fan. Therefore, such a cooling system is considered dynamic. The air moves, providing a fast and even distribution of cold.

No Frost was invented by the Italians at the Zerowatt factory, which is now part of the Candy group of companies. Today, this development is used by most refrigerator manufacturers.

Classic two-chamber refrigerators with No Frost (freezer)

How does the No Frost system work?

In general terms, the principle of operation of No Frost cooling is as follows:

1. Usually the evaporator of a refrigerator with No Frost is located behind the back wall of the working chambers. Otherwise, it performs a task that is quite standard for any refrigeration unit: it converts the refrigerant from liquid to vapor. And during this process, cold is released and the available heat is absorbed.

2. In addition to the evaporator, there is also a fan and an air duct system behind the wall. Through them, the forced movement of cold air is carried out. Air flow distribution schemes most often differ from manufacturer to manufacturer. Movement can be horizontal or vertical. Streams are common for all chambers or separate for the refrigerator compartment and freezer. And sometimes even a special door airflow is provided, like LG refrigerators with Door Cooling + technology. But the meaning of the circulation is unchanged - to ensure uniform cooling and quickly achieve the required low temperature.

This is what the wall of the refrigerator compartment looks like with No Frost.

3. Moving air currents “blow out” moisture (condensate) from the working chambers. And you need to understand that its formation is inevitable both when adding new products to the shelves, and every time you open the refrigerator door and warmer air comes in from the outside.

4. Moisture settles on the evaporator and turns into frost. The more it is formed, the lower the cooling efficiency becomes. With complete icing, cold air simply could not get into the compartment. But to prevent this from happening, at certain intervals the fan and compressor automatically turn off (it compresses the gaseous refrigerant coming from the evaporator and feeds it back in liquid form).

5. During the refrigeration pause, the automatic defrost phase starts. The heating element located on the evaporator turns on. So the frost turns into water, and that through the drainage channels enters a special pan. Later, it evaporates from the heat generated by the compressor.

6. When the evaporator thaws, a new refrigeration cycle is started with blower operation. And everything repeats again.


As a result of this work, No Frost maintains a more stable temperature in the refrigerator, and users do not need to deal with icing on their own.

The same temperature at the bottom and at the top is one of the advantages of No Frost.

What is No Frost made of?

The main components of the system are still considered the compressor and evaporator. But in addition to them there are other components, namely:

  • fan and air channels. They provide air circulation, including directing cold into the working chamber and taking excess moisture out of them;
  • tubular heater (TEN), structurally similar to those used in washing machines or other household appliances. It participates in the process of automatic defrosting of the evaporator and helps to reduce the time of this phase;
  • defrost timer. This is a small relay that turns on the heating element at predetermined time intervals and simultaneously turns off the compressor;
  • fuse thermostat. This component is also a special relay responsible for turning on the compressor when the temperature rises to the set point. The thermal fuse, in turn, excludes overheating and other unforeseen work scenarios.
Here's what's behind the back of the No Frost fridge.

The timer, thermostat and other relays are used in refrigerators with a mechanical No Frost system. In many modern models, they have been replaced by electronics. It is a small board with a microprocessor and a set of sensors. Such an electronic module regulates all phases of cooling, controls the fan and the heater.

Electronic module No Frost.

Varieties of refrigerators with No Frost

More and more manufactured refrigeration units provide for the No Frost system. At the same time, manufacturers can give different names for essentially the same technology.

Initially, the No Frost system was used only for freezers of refrigerators. Similar things happen now. In such a case, simply the designation No Frost or the term Frost Free may be used. The latter is used by Candy and Electrolux, and also, for example, in Freggia built-in refrigerators. In the refrigerator compartment, in this case, an alternative technology is usually involved, for example, static cooling with drip defrosting (more on this later).

Classic Two-chamber Fridges with Full No Frost

Today, much more often, the No Frost system applies to the entire internal volume of refrigerators. When channels for the circulation of cold air are provided in both the refrigerator and freezer compartments, the term Full No Frost is most often encountered, but sometimes a synonym is offered - Total No Frost (for example, LG and Indesit).

A complete No Frost system can also be called total.

Advanced variations of the system are also possible. These include Twin Cooling System in Samsung refrigerators or Dual Cooling from Beko and other manufacturers. Their essence lies not only in the presence of two independent cooling circuits, but also in the presence of a separate evaporator and fan for the freezer and refrigerator compartment. As a result, the possibilities of temperature control are expanded, and the air in different chambers does not mix. Plus, it is possible to increase the level of humidity in the refrigeration compartment, which is the Achilles' heel of the classic No Frost.

Competitors No Frost

In addition to the "No frost" system, when choosing a refrigerator, 3 alternative cooling technologies are available to customers. Let's consider each:

1. Static system with drip defrosting. This is one of the oldest technologies that has stood the test of time. It is also called "crying" or Direct Cool. The traditional type of cooling is used here: when the evaporator is built into the rear wall of the working chamber. It also reduces the operating temperature, but on the upper shelves it can be several degrees higher than on the lower ones. Condensation forms on the back wall and turns into frost. And so that there is no ice “coat”, drip defrosting is implemented: periodically the compressor turns off, the frost thaws and flows into a special drainage hole. Such refrigerators are often referred to as drip refrigerators.

Drip Coolers

The advantages of such a system: affordability and preservation of moisture products.
Cons : uneven and slow cooling, condensation in the working chamber, which can cause bacteria to multiply and unpleasant odors, the inability to implement drip thawing in the freezer (here the temperature cannot be raised to positive). Accordingly, the freezer compartment must be manually defrosted periodically (usually several times a year).

The main difference between a freezer with a static system and No Frost.

2. Dynamic system with drip defrosting. The principle of operation is almost the same: there is a “weeping” evaporator wall and drip defrosting, but a fan is proposed for more uniform cooling.

Pros: no problem of different thermal zones, preservation of product moisture, the intensity of condensate formation is lower than in "static".
Cons: the freezer must be defrosted manually, a small range of models (units with No Frost are more often on sale than refrigerators with dynamic cooling and drip defrosting).

To eliminate the main disadvantages of the first two systems allows the tandem of No Frost in the freezer and drip thawing in the refrigerator (with dynamic or static cooling).

3. Technologies for reducing the intensity of ice formation in the freezer compartment. These primarily include the development of Bosch - Low Frost. Here, the evaporator is placed on the inner walls of the freezer and occupies almost their entire perimeter. As a result, the temperature in the chamber is less subject to fluctuations, which means that frost appears much less than in classical cooling systems. The frost covers the walls with a thin coating, so the manual defrosting procedure takes a minimum of time (usually a little more than an hour). And appropriate care is required somewhere 1 - 2 times a year.

Today, Low Frost technology is used not only in the units of the German concern, but also, for example, in Gorenje refrigerators.

Pros: uniform freezing, preservation of food moisture.
Cons:: can not do without manual defrosting.

A compromise between Direct Cool and No Frost.

Pros and Cons of No Frost

The main advantages of the "No frost" system include:

1. Minimum care requirements: defrosting is automatic.
2. Uniform cooling.
3. Quick return to operating temperatures after downtime / adding a large amount of food.
4. No condensation in the working chamber, and therefore no unpleasant odors or risk of bacteria growth.
5. Large range of new models. In recent years, there have already been more stand-alone units with No Frost produced than drip ones, which means there will be plenty to choose from.

Vessels are excellent fighters against overdrying from No Frost.

Flaws:

1. Higher price than refrigerators without No Frost (fee for convenience).
2. Risk of overdrying food. Together with the condensate, the moisture of the food itself is “blown out”. But this is true primarily for sliced products. They quickly become weathered and may deteriorate earlier, so it is recommended to pack them or store them in vessels. But whole fruits and vegetables are not subject to such a problem and, on the contrary, are stored longer than in models with drip thawing.
3. Higher noise and power consumption possible. But here everything depends on the price segment of the model and the quality of components, as well as other variables, including the type of compressor: the default inverter will be more economical and quieter.

The question of reliability and other myths about No Frost

Refrigerators "Without frost" are sometimes credited with those minuses and pluses that are not really inherent in them. Here are the main myths:

1. The reliability of No Frost is lower than the drip system. Everything is not so clear here. Yes, static cooling with drip defrosting is a classic with a high level of reliability, and No Frost has more components, which means, theoretically, the risks of their failure are higher. But there are also counterarguments. For example, in No Frost, the evaporator is better protected from accidental damage (hidden behind a wall). Plus, this component is easier to repair (it is not foamed and not covered with insulation), and other components (heater, thermostat and relay) are relatively inexpensive and also easy to change even without a repairman. It's also fair to say that the overall reliability of a refrigerator depends more on other things, like the material of the evaporator tubes. And in models with No Frost, they are often copper (higher quality), rather than aluminium.
2. Models with No Frost are harmful. According to rumors, another refrigerant is used here, dangerous to human health. This is a fiction, since the same types of freon are used here as in drip models.

Refrigerators with No Frost should not be left completely without care.

3. Refrigerators with No Frost can be defrosted for years. From a technical point of view, this is true, because defrosting occurs automatically. But there is still common sense and basic hygiene when it comes to food storage. In the refrigerator, pollution is sure to appear over time, some food deteriorates, so ideally, once a year, even models with Full No Frost are recommended to be unplugged and cleaned.

As a conclusion

No Frost is a dynamic refrigeration system (with forced air circulation by a fan) and an automatic defrost function that eliminates the need for manual defrosting. The main differences from modern models with drip defrosting can be considered the presence of a heating element and additional components that regulate its operation, as well as a different location of the evaporator. It is not built into the rear wall, but is located behind it, so there is no frost on the working surfaces of the chamber.