Known water coolers are used both for air conditioning units and for various applications requiring a heat treatment by means of cooling water as heat-carrying fluid (for instance industrial processes, labs, elec- tromedical appliances, instrument cooling, food indus- try, etc.).

In the field of air conditioning coolers mainly differ in the cooling power they supply and in the system they use for subtracting heat from the condensing por- tion. More specifically, fluids commonly used for sub- tracting heat transferred from the cooling cycle are air and water.

Air condensed coolers do not require any water con- sumption for their operation, since condensation heat is wholly transferred to air.

However, quite large air volumes are treated, which generally involve an external installation for these appliances. The rare cases of internal installation involve complex structural works for the canalization of air flows. Conversely, water condensed coolers are usually placed inside, since no external air flow is required for their operation. The great disadvantage of these ap- pliances is related to a high water consumption strongly limiting their practical use.

The basic principle underlying the operation of most coolers is the cooling cycle by compression of satu- rated steam, which basically requires the use of a compressor, a condenser, an evaporator and a lamina- tion element.

Water coolers based on the principle of low pressure steam absorption by a concentrated solution (ammonia- water or lithium bromide-water) have a small portion of the global market.

Various types of cooling compressors can be used in a cooler, such as for instance: - Reciprocating airtight compressors, where an elec- tric motor moves a piston-cylinder compression system (such as in piston pumps). This type is used in mid- dle-size and large coolers.

- Rotary compressors where an electric motor moves a pump element comprising a piston, eccentric with re- spect to a cylinder. The side between high and low pressure is separated through a metal wall sliding within a hollow. This type of compressor is mainly used in small coolers.

- Scroll compressors. Here again the mechanical move- ment is generated by an electric motor. The compres- sion of the cooling fluid takes place thanks to the movement of two concentric spirals pushing the fluid from spiral periphery to the center. These components are used in middle-power coolers.

- Single or double screw compressors: these are char- acterized by a highly silent operation and by an opti- mal thermodynamic performance, and are used in middle- size and large coolers.

- Centrifugal compressors working on the basis of a turbine-like principle, used only for large coolers.

Heat exchangers used for transferring heat flow from cooling medium (usually HFC or more seldom ammonia, hydrocarbons or C02) to water or water-glycol mixture and vice versa, are basically tube sheet or braze- welded sheet exchangers. The first ones have a higher operating reliability, above all in case of polluting or smearing substances in the hydraulic circuit or in treated water. The second ones have better perform- ances in relation to their size.

Heat exchange batteries used for transferring heat from cooling medium to air and vice versa comprise copper tubes coated with aluminum wings increasing heat transmission surface.

Fans for carrying sufficiently large air flow rates for subtracting (cooling cycle) or releasing (heating cycle) heat are basically of two types: - Axial fans: where air flow gets axially through the impeller, which has the shape of a helix with differ- ent profiles depending on flow rate and discharge head . properties of the motor-ventilating unit. These appli- ances are mainly used in external coolers.

- Centrifugal fans: these aeraulic appliances suck air through a shaped mouthpiece arranged on fan center.

Air is carried outside the impeller by the centrifugal force generated by the rotation of said fan. By using a convenient screw conveyor, which can increase its dynamic component, the air flow is pushed towards the outlet. Centrifugal fans are generally used for cool- ers placed within buildings. As a matter of fact, thanks to the static and dynamic discharge head of these ventilating units it is possible to carry out canalizations for conveying'air outside.

The difficulty in diffusing common air conditioning units using water coolers using air as fluid for sub- tracting heat from the condenser, above all for domes- tic installations, is related to the external room to be found and used for installing the whole cooler or its condensing portion, and quite often to the high skill required for carrying out hydraulic or cooling connections.

These problems can be solved with a cooler having a water condenser, but with these appliances water con- sumption can reach 3,000-4, 000 liters/day for cooling a medium-size or small flat. Obviously, such appli- ances can therefore be used only in geographical areas with wells or sources other than municipal waterworks (particularly abundant water-bearing creeks, rivers or streams, marshes, etc.).

The technical task underlying the present invention is to solve the drawbacks of the state of the art.

In particular, the present invention aims at solving the problems involving installation and high water consumption due to air condensed and water condensed coolers, respectively.

These and other aims, which will be evident from the following description, are basically achieved by a wa- ter cooler having the characteristics of claim 1.

Further characteristics and advantages will result from the detailed description of a preferred, though not exclusive, embodiment of a water cooler according to the present invention.

Such description is disclosed below with reference to the accompanying figures, provided to a merely indica- tive and therefore non-limiting purpose, in which: - Figure 1 shows a sectioned view of a water cooler according to the present invention; - Figure 2 schematically shows an example of installa- tion of a water cooler with two pipes and correspond- ing holes in a wall; - Figure 3 shows a second example of installation of a water cooler, the outlet of the pipes being located on an appliance side fastened to the wall; - Figure 4 shows a view as in Figure 1, referring to a variant of the water cooler.

The layout section shown in Figure 1 helps to give a clearer description of the present invention.

The water cooler, globally referred to with number 20, comprises a frame 2 to which a cooling compressor 1 is fastened. Through an intake tube 3 the cooling medium is sent to an evaporative condenser 4, which is also integral with the frame 2. The water to be evaporated on the condenser is taken by a pump 5 from the tank or basin 6 and through the tube 7 and the dispenser 8 it is sprayed onto the evaporative condenser 4. After be- ing condensed, the cooling medium expands in the cap- illary tube or lamination valve 9. It is further pro- vided for an evaporator 10 in which water to be sent into the closed circuit supplying terminal air condi- tioning units is cooled. Through a return tube 11 the cooling medium gets back to the compressor 1. A fan 12 ventilates the evaporative condenser 4. Humidity- saturated air is let out through the pipe 13. The air getting through the evaporative condenser is taken outside through the pipe 14. A chassis 15 to be fas- tened to the frame 2 encloses in one structure the whole cooling appliance 20. In order to avoid high concentrations of limestone that could rapidly turn into scales within the tubes, the water contained in the basin 6 placed under the evaporative condenser 4 can be periodically changed. Water drainage occurs through a siphon 16 which is actuated when the level is increased by means of a loading valve. It is thus possible to avoid the use of expensive motorized or electromagnetic valves and the operation of the cooler 20 becomes more reliable.

Figure 2 shows a typical installation of the cooler 20 with pipes and their corresponding holes in the wall 19, which are made behind the appliance 20 according to the present invention. This example also shows two grids 17 preventing large foreign bodies from entering the pipes 13 and 14. Figure 3 shows a second installa- tion with the outlet of pipes 13,14 on a side of the appliance 20 fastened to the wall 19.

Figure 4 shows a pattern as in Figure 1, though with the addition of a water condenser 18 upstream from the evaporative condenser 4 for producing hot water for sanitary use. Through this appliance 20 condensation heat can be transferred into a water tank for sanitary use. This means that whenever the cooler 20 is used for air conditioning purposes, hot water for sanitary use is produced almost free.

The present invention can be integrated with a common boiler for producing hot water for heating purposes and hot water for sanitary use. This integration can be carried out also within the same chassis, thus ob- taining one appliance.

The main technical solution that enabled to solve the technical task disclosed above has been the applica- tion of the principle of evaporative condensation in a single-block cooler for internal installation. The op- erating principle of the evaporative condenser is based on heat transfer through water change of state from liquid to steam. The amount of energy required for this change is, as is generally known, quite high (650 W pro kg). Thus, with the use of a small amount of water high heat transfers are obtained.

The technology of evaporative condensation has been known for years, but it has always been applied to large units, in the field of air conditioning and of industrial cooling. Further uses have involved the field of stand-alone portable air conditioners. In ap- pliances for centralized systems, evaporative condens- ers are used instead of the more widespread evapora- tive towers, provided that tubes for cooling medium circulation are not too complex and involve too great installation problems.

The greatest advantages deriving from this solution for transferring heat from the cooling medium to the external environment (condensation step), with respect to an air exchanger are related, beyond to a consider- able size reduction, also to a relatively low conden- sation temperature (saturation pressure in the con- denser). This results in a higher EER (energy effi- ciency ratio) with accordingly lower energy consump- tion for the supplied cooling power. Beyond this an- other advantage is the lower operating noise due to smaller air flows to be circulated by the fans.

With respect to water condensers the amount of this fluid used in an evaporative condenser is extremely smaller (1/20).

The present invention allows water coolers supplying quite a relevant number of air conditioning terminals (houses, offices, hotels, public spaces in general) to be installed inside, requiring only two small holes for communication with outside. This feature enables to install these appliances almost as if they were boilers. As a matter of fact, no cooling connections will be required, and above all it will not be neces- sary to arrange any other device outside.

The exploitation of evaporative condensation, as was said before, enables to highly reduce air flows and the size of coolers with respect to coolers exploiting air condensation. Air flow rate for the operation of small coolers with evaporative condensation (4-10 KW of cooling power) for independent domestic use can circulate in pipes with a small diameter (100-200 mm) and an easy positioning. The holes required for commu- nication with outside can be easily made by a common core boring drill. Water consumption sinks dramati- cally to values that can be accepted in all geographi- cal area (12-25 liters/hour).

The size of these new coolers will be small and how- ever compatible with the installation inside common houses or residential buildings, as occurs for other appliances such as boilers or water heaters. Hydraulic connections will enable an easy and rapid coupling with the thermohydraulic system.

The new coolers can also be mounted as one chassis to- gether with a wall boiler, thus creating a complete, stand-alone unit for producing hot and cold water.

The invention has important advantages. The cooler for simplified internal installation according to the pre- sent invention provides an extremely high flexibility of use and can meet almost all needs of internal posi- tioning and greatly simplify installation. Moreover, the invention enables to obtain an arrangement of in- let and outlet pipes that is always optimal for any type of installation. It should further be pointed out that the invention enables to obtain a cooler with a simple structure and an'easy construction, which thanks to the possibility of making appliances with a small size depending on their cooling power, allows to greatly reduce manufacturing and storing costs.

The invention thus conceived is subject to several changes and variants, all of which fall within the in- ventive idea characterizing it. Furthermore, all de- tails can be replaced by technically equivalent ele- ment and any size, depending on needs, can be used.