Depending on their structure, refrigerators are divided into five categories, within which there are differences based on size, however the following categories can still be applied: single/ one-door, double door, combined (fridge-freezer models), three or four door and side-by-side. Let us now look in more detail at what each of these five fridge models looks like:

1) Single door refrigerators, this model is shaped like a rectangular parallelepiped conventional refrigerator with a single door at the front. It has an internal, variable temperature control between 4°C and 28°C. One-door refrigerators vary in height and storage capacity, starting with models of 50 litres and going up to products capable of holding around 360 litres and more. In this case the dimensions of the fridge are completely different starting with small shapes of a 50cm height up to those reaching heights of 180 cm.   Energy consumption is low and can be classified with a high A+ energy efficiency level. As a general rule, these fridges come without a freezer, however in some models it is possible to find a small, internal ice storage compartment qualified with a 1-star energy rating. Some manufacturers also sell freezers in addition to the fridge, with the same appearance and dimensions, in order to allow you to buy both and thus form a unique unit.

2)Double door, this is a single unit, divided in two horizontally creating two separate compartments, with the fridge on the bottom and the freezer on the top.  As a proportional indication, the small freezer compartment mounted on the top takes up 1/5 of the space and the large fridge compartment takes up 4/5 on the bottom. These are ideal for people who need fresh and frozen food over a medium/ long-term. From a technical point of view, both compartments are operated by a compressor, the temperature of which is regulated by a thermostat positioned either inside or on the outside of the fridge according to the model.  Depending on the available technology, there may be a single thermostat that runs both the fridge and the freezer, clearly governing them at different temperature gradients. In contrast there may be two separated thermostats to monitor the temperature of the two compartments in a specific way.

3) Combined refrigerators, these were born out of the idea to combine (hence the name) two compartments, with one on top of the other, operated by two separate compressors. The idea came about 10 years ago, then, with the evolution of technology and an increasing necessity for a higher performance product with a low energy consumption, the new generation combination was born: a unit run by a single compressor operating between the two compartments and with the characteristic of having two separate temperatures that are not dependent on each other. Equally in this case there are differences between models according to the technology used and therefore we can find combined refrigerators with one thermostat as well as with two.

4) Three or four door refrigerators, this is a very limited category, produced solely by some companies. The idea was born out of unique designs that have led to quite large refrigerators, with heights of 70/80 cm, in which the refrigerator is on top with a double-door opening and the freezer is on the bottom either with one or two doors or with two drawers. As far as the temperature is concerned, it runs in the same way as the other models.

5) Side by side refrigerators, these are also defined as American refrigerators due to their origins (it is the classic refrigerator used by Americans). Esthetically, they look like a type of wardrobe with two doors, of which one is narrower and on the left side (the freezer) whilst the other is larger and on the right (fridge). A dividing panel positioned slightly to the left of the centre separates them. In addition to the classic form, some American refrigerators with four doors have gained strength on the market. These have two doors for the fridge and two for the freezer, with the compartments being divided in a different way: the fridge is on the top and the freezer on the bottom. This system has allowed the construction of a fridge compartment without a dividing panel, thus offering a space and practicality that had never before been possible with the combined style of refrigerator. The cooling technology used is that of two separated thermostats and the cooling system is a ‘total no frost’ system.

Between these various categories beyond the presence of technical differences in construction, there are small differences that don’t generally result in any changes to the quality of the refrigerator, but simply alter the appearance. There can however be a substantial difference in terms of the cooling technology.  When analysing this we find ourselves faced with the following ways of referring to refrigerators: static, dynamic (ventilated, DAC, air system and other systems), no frost and dynamic frost-free.


A refrigerator with this type of cooling system can have a volume varying from 50 to 450 litres and in some cases even more. It is the most classic cooling system and can associated with refrigerators featuring either one or two compressors, with a double refrigeration circuit or a single one for both compartments.

Distribution of cold air: this takes place in a ‘natural’ way, this signifies without the help of an active or forced ventilation fan to move the air. The gas, whilst moving along the refrigerator circuit, enters into contact with the hot air inside the cold stores and carries it outside, expelling it by means of an evaporator. The cycle is continuous until the set temperature has been reached. In the freezer cold store the same process takes place, simply at a lower temperature.

The refrigerator is self-defrosting whilst the freezer generates frost which sticks to the back walls and thickens to the extent that the compartment must be defrosted. The temperature inside the refrigerator is not uniform on all of its shelves; there are differences of as much as a few degrees higher in the highest shelves, whilst the lowest part is the coldest.


The term dynamic refers to the movement that takes place within the refrigerator during the forced ventilation of cold air. Without entering into the particularities of each individual technology, or better yet without referring to the names that each company has attributed to its own dynamic system (ventilated, DAC, air system, turbo and others), let us just say that, in general, the fundamental principles of operation are the same for all of them, as is the final result.

With the help of a ventilation fan, positioned on the inside of the refrigerator compartment, the air is circulated and distributed in a more uniform way inside the fridge, in an attempt to make the temperature as equal as possible at all levels. In comparison to a static refrigerator variations in the temperature gradation will be much more limited, however the highest part still remains the hottest and the lowest the coldest. The dynamic process allows for a better conservation of food prolonging the storage time. 

The freezer is not affected by this process, it works exactly as before, in other words it is static and therefore needs regular defrosting.


It means that it doesn’t produce frost and therefore doesn’t need to be defrosted. The system is characterised by the presence of a compressor that feeds both the refrigerator and the freezer, and a double evaporator; these two circuits singularly responsible for both the refrigerator and the freezer. The temperature and functioning of the two unit compartments are independent from each other. During the process in which the refrigeration gas is expelling the heat, the cold air enters the stores through a ventilation system whilst the treatment of the air eliminates any moisture from humidity and prevents frost forming in the freezer.Meanwhile in the refrigerator the lack of moisture prevents mould from building up and bad smells.

In general, the cold air is dry, so the food tends to dry out if not properly covered, or put into containers.  On this last statement, we need to be more precise, in the sense that no-frost cooling technology has evolved and many refrigerators now have a system to monitor and ensure the maintenance of moisture inside the cell. Therefore, the consolidated notion that the no-frost system dries out food is slowly being abandoned.


This is a new product on the market, born out of the "fusion" between a ventilated refrigerator and a total no frost cooling system, using parts of both technologies. The aim is to take advantage of the two technologies and consequently to eliminate their disadvantages. In the refrigerator the air is distributed with the aid of a ventilation fan, which is able to make the temperature uniform in the store while maintaining the moisture at an optimal level, thus ensuring the food will remain fresh for longer. The freezer operates on a frost-free system to prevent frost from forming and it eliminates the annoying problem of having to defrost the freezer.

The two compartments are separated and fully independent, unlike in some no frost systems, therefore smells cannot be mixed and best of all there are no changes made to the moisture levels or temperatures.


No technical procedures are required, but we must take some measures into account that will improve the quality of the fridge functioning and of its energy consumption performance.. The refrigerator should not be placed near heat sources to avoid overworking the compressor and consequently an excessive energy consumption. Such heat sources include: cookers, heaters and sun exposure as this  also produces heat. It must be positioned at a distance of at least 10 cm from the wall, thus allowing the air to circulate freely in the coils. This efficient exchange of air allows for a faster cooling system.


This s important both for the duration and above all the quality of food preservation. The cleaning of the compartments can be done with a cloth soaked in vinegar and water so as to disinfect and degrease eliminate unpleasant odors. Never use knives or anything sharp to remove the frost from the freezer as you could irreparably damage the product. Do not forget to clean the condenser, the black part/tubes going up behind the fridge, in this way you ensure its long duration.


In the specifics e of the table, from top to bottom, the first letter refers to the class, then the annual electrical energy consumption is indicated, followed by the net internal volume first of the refrigerator compartment, then of the  freezer, an indication of the energy star qualifications/ levels, and finally the sound level (of power and pressure) expressed in decibels.

energy label frigorifero

More details are available on the Energy Label page.


It is essential to install a defroster properly to gurantee the quality of freezing and to maintain the energy consumption levels. The freezer must be defrosted whenever the frost exceeds the thickness of five - six millimeters. The frost is formed due to the freezing of the vapors generated by the food and in becoming thicker creates an insulating layer that prevents the proper functioning of the freezer.  When The defrosting  you must not use sharp objects that could damage the refrigerator, but be patient and wait for the ice to melt before switching off the freezer.

Published: monday, july 16, 2012
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