An inverter is an air conditioner, who has smooth control of the compressor according to the set temperature in the room. The inverter systems are 30% more economical than conventional, because of fewer times defrosting per unit.Modern invertors have coefficient of performance/COP/ between 3 and 5.7. Inverter compressor adjusts its speed, which spend more energy, when they are deployed with the minimum-necessary speed. Inverter compressors are four types: "Screw", "Scroll", "Rotor" and "DC PAM". The inverter efficiency comes due to monitor various parameters during operation (input-output pressure, input-output temperature). The new models of Mitsubishi Heavy Industries used "DC PAM" compressor and also with high-tech heat exchangers are market leaders in energy efficiency COP (5.7). An example is the model SRC / SRK 20 ZJX-S: maximum power consumption - 0.7 kW, heating power in the room - 4.3 kW.

In the compressor of the DC invertor air conditioners is used an electromotor developed by the Japanese Institute of Technology. This electromotor has no coils of copper wire in its rotor, but Neodymium magnets which are located in the electromagnetic field created by the stator. As is well known from physics , the placing of a magnet in an external magnetic field creates a force that causes the magnet to rotate and to orient by its magnetic poles – similar to the movement of a compass needle, which is a magnet placed in the Earth's magnetic field.

Except for this magnetic force, this DC electromotor uses another power – the power of magnetic resistance, as the usual DC motor does. These two forces make it possible to achieve about 5% higher efficiency than a conventional DC motor when the rotor rotates at 100 rpm. In such modern air conditioners the the rotor speed is used when the air conditioner running at full power.

Greater efficiency and savings, however, occurs when the rotor rotates at low speed, which is the most common mode of most air conditioners. At low revs the motor efficiency is about 20% better than the efficiency of the AC eletromotor and about 10% better compared to conventional DC.

BTU (British Thermal Unit) is a basic measure for quantity of thermal energy. 1000 BTU/h is approximately 293 W. At some places, is written in the joules (J). 1 BTU is equal to 1.055 joules. In their product lists, manufacturers usually offer air conditioners with air-conditioning capacity measured in BTU. This is why some air conditioners are called “Nines”, “Twelves”, etc. EER (energy efficiency rating - Energy efficiency ratio at cooling mode of the conditioner) and COP (coefficient of performance - Energy efficiency ratio at heating mode) are equal to the ratio of power output in BTU to the power in W (watt) for the current mode. The aim of the producers is as higher EER as possible, but this leads to the application of technology and technical implementations with high price. Air conditioning systems of inverter type are now available with EER higher than 5. For example, by 2011, Mitsubishi Heavy Ind. have a hyper-invertor model SRK / SRC 20 ZJX with EER 5.56, COP 5.71.

The ratio of W to BTU is approximately 1 to 3.41

The 92/75/EES Directive of the European Union of 01.01.2004 on qualifying air conditioning installation, distributed commercially, certifies the classes of energy efficiency of air conditioners from Class A (highest energy efficiency) to Class G (lowest energy efficiency). Thus users can compare the effectiveness of the same types of air conditioners of various brands. For example, the European Union experts have found that by increasing the energy efficiency of air conditioners by only 5%, the payback period of the investment significantly shortens. At an average lifespan of 8 years of Japanese air conditioners, the return from saved electricity consumption is between 2 and 3 years for the models with high performance (Class A).

Basic model of the operation of air conditioners

Compressor - it sucks and pumps the freon, it maintains its motion round the refrigerant circuit.
Condenser - a radiator located in the outdoor unit in cooling mode. The name derives from its job in the conditioner – the transition of the refrigerant from gaseous phase to liquid phase (condensation).
TEV (thermoregulating valve) - it lowers the pressure and temperature of the refrigerant before the evaporator.
Fan - creates the flow of air, serves the evaporator and the condenser. It is used for greater intensity of the heat exchange with the environment.

The compressor, the condenser, the TEV and the evaporator are connected by copper pipes (sealed), in which the refrigerant and a small amount of compressor oil are circulating.

In the process of work of the conditioners the following happens: at the entrance of the compressor out of the evaporator enters gaseous gas with low pressure (3 - 10 кg/сm²) and low temperature (10-20 degrees Celsius). The compressor sucks the refrigerant and heats it up to 41.7 кg/сm² and 70-90 degrees Celsius, then it enters the condenser. Due to the intense fanning the refrigerant radiates heat to the air, who pass through the condenser. As a result the Freon condenses. At the exit of the condenser the freon has temperature of 10-20 degrees Celsius higher than the air. From the condenser the cooled freon enters in TRV ,which in our case represents a capillary (a thin copper pipe coiled in a spiral), where the temperature and pressure are reduced and the freon begins to evaporate. After the TRV the freon begin to pass into a gaseous state and in the end of the evaporator it is absolutely gaseous. The gaseous refrigerant with low temperature goes to the entrance of the compressor and the cycle repeats. This principle is the basis used for the work of each conditioner and does not depend on its type, model or manufacturer.

At the air conditioning systems the electricity is used to power the movement of air conditioning mechanics and its management. In the system there is circulating refrigerant which at transformation from liquid to gaseous state takes heat (cools) and at transformation from gaseous to liquid state gives the taken heat (heats).

The compressor of the air conditioner sucks gaseous freon and turns it into liquid, which increase its pressure and temperature . Depending on whether the outdoor or indoor units are the place where the liquid refrigerant shall expand to its gaseous state, the air conditioning works on cooling or heating mode.

R-22 is a hydrochlorofl uorocarbon (HCFC) which was commonly used in air conditioning systems. When R-22 is released into the air, the ultraviolet rays of the sun cause it to decompose and chlorine is released in the stratosphere. Chlorine reacts with ozone, reducing the amount of the ozone. Due to ozone layer depletion, harmful ultraviolet rays reach the surface of the earth giving rise to a number of health and environmental issues.

The international community therefore, signed the Montreal Protocol to phase out ozone depletion materials by 2030. The European Union however, decided to ban R-22 already in 2015.

2010 - ban on the use of unused R-22 for service and support
2010 – 2015 - only the use of recovered and recycled R-22 is used
2015 - ban on the use of all types of R-22 for services and maintenance


As currently not enough R-22 is reclaimed to cover the demand, supply shortages and price increases are expected. If there is no reclaimed R-22 available certain repairs (for example: compressor change) are no longer possible and considerable air conditioning system downtime can occur. It is therefore worthwhile to consider a replacement system before 2015, especially for air conditioning systems with a large impact on the daily running of the business.

DAIKIN SOLUTIONS TO R-22 PHASE-OUT

For Sky Air®, re-use technology is available on Super Inverter, Seasonal Inverter and on the newly developed RZQG-series. Thanks to this technology these units can be installed using existing R-22 piping.

For VRV® installations, VRV®III-Q solution allows retaining existing R-22 piping and in some cases even the indoor units and controllers.

* Information from the Catalogue of commercial applications - Daikin 2011.

Because of the European legislation which puts pressure on energy consumers for drastical shrink in consumption, improvement of energy efficiency in buildings and achieving the so-called purposes "20/20/20" of the EC, the sector is seeking better ways to evaluate efficiency. Thus, the directive on eco-design of the European Parliament aims to reduce the harmful effects of products on the environment in the EU. This is why a measure on air conditioners is currently being developed and it will introduce a new method for estimating efficiency – seasonal efficiency instead of the current method for nominal efficiency.

The current method for estimating energy efficiency, namely the nominal efficiency method, however, has limitations, which leads to a significant discrepancy between the nominal and actual performance. To correct this situation, a more complicated method of calculation is developed in parallel with the eco-design and prEN 14825 / 2010 version /. The main differences between the season and nominal calculations are:

- At nominal efficiency there are rules for temperature – 35 degrees C for cooling and 7 degrees C for heating. At seasonal efficiency there are several nominal temperatures for heating and cooling, which reflects the actual performance throughout the season.

- At nominal efficiency the full capacity is not considered and the advantages of inverter technology cannot be evaluated. Seasonal efficiency includes work at partial, rather than at full capacity and the advantages of inverter technology are clearly shown.

- At nominal efficiency is the ancillary modes are not taken into account, wheres at a seasonal efficiency the consumption in the following modes is included: thermostat off, standby mode,crankcase heater, off mode.*


* Information from the Catalogue of commercial applications - Daikin 2011.

The precise project is the safest way to avoid unpleasant surprises in the process of implementation of an installation. Frequently (especially at small buildings) this vital step is missed, counting only on the subjective decisions of the implementers. The project clarifies all uncertanties about the choice of the most appropriate system and the subsequent implementation. It gives a clear account on the quantities of the materials – an account that can be presented to several companies for receiving an offer and thus it saves from both the initial investment and the monthly payments for electricity.

A lot of companies supply the market with Japanese inverters - second hand!

These models of inverter air conditioners are manufactured in Japan and have worked between 5 and 8 years, and are actually obsolete models. Some of the models are designed for the Japanese domestic market and do not meet the standards for power in Europe. In Europe the power supply is 220/240 volts and 50 herz, but in Japan the power supply is 100/110 volts and 60 herz.

Another major problem is the supply of spare parts for air conditioners that the local market do not sell.Often the air conditioners second-hand should be reconditioned with an old unoriginal parts,which are not from the same model and type. Important for the human health the air conditioner air filters are dirty and worn. They are not subject to a complete wash, but finding new filters of the same model may be impossible.

One air conditioning system consisting of one outdoor and one indoor unit should not be used for cooling or heating of two rooms, unless it is a multi-split system (one outdoor unit with two, three or four indoor units).

This problem might have a partial solution if both rooms share one door. In one of the rooms the air conditioning system can be put and installed against the door. Its power must be consistent with both rooms size. The airflow will naturally move from one room into the other. The cons of this solution are that there will be a temperature difference in the process of heating of the two rooms, which sometimes can reach 10 degrees. The problem is that hot air remains at the top of the room and can not overcome the overdoors; also both rooms can not really have their doors open all the time.

In order to work properly and not to stop operating prematurely, it is necessary to regularly (usually once every two weeks) clean the filters (with water and detergent), located under the front panel of the indoor unit, as well as to monitor the status of the outdoor unit. If you notice irregularities (unusual contamination, leaning, smash, etc.), disconnect the unit immediately and call a service technician.

At least once a year we recommend prophilactics of the air conditioning which is performed by the technicians who installed the conditioner. Prevention is needed and necessary to allow the conditioner to be used for a long time and should by paid separately.

There are the following types of filters:

- Allergen-deactivating Filter Completely destroys pollen, parasites and allergens that exist in the fur of pets. The secret of this deactivation lies in the compound enzyme-urea. It not only deactivates allergens, but it also neutralizes and kills all bacteria, fungi and viruses. Even if allergens, bacteria , etc. go into the filter, they are already disabled and the air in the room is kept clean and fresh.

- Natural Enzyme Filter Enzymes used in these filters are naturally occurring "lytic" enzymes. "Lytic" enzymes attack the cell walls of microorganisms trapped in the filter and destroy them. They have a strong sterilizing effect, decreasing the number of molds and bacteria. The natural enzyme filter cleans and disinfects the air circulating in the room and keeps it clean and safe.

- Photocatalytic Washable Deodorizing Filter Keeps the air fresh by removing odors molecules. Deodorizing power is restored by washing and drying in the sun. This is a filter that can be recycled and reused.

The filters are part of the set of additional filter of the models of air conditioning systems Mitsubishi Heavy Ind. and can be purchased at our office at 34 A “Dr. Zhelezkova” 34 for 25 BGN.

It depends on the air pollution in the region. It is important if the air conditioner is located in the city center or in a quiet place where there are no busy streets and no cars passing. Some models have an indicator of the expiration of the filters. Additional filters expire for 1 year.

In winter mode, the refrigerant evaporation takes place in the outdoor unit at about - 20 ° C. The air that the fan of the outdoor unit passed through the heat exchanger contains humidity,which frosted the unit pipes, like the evaporator of the chamber of the residential refrigerator. When air conditioner is in a frost mode this frost melts and flows out. But if the ambient temperature is below 0 ° C, then part of the water ,depending on that how cold it is outside, can not run completely and freeze because of the low environment temperature. This process usually starts at the bottom of the "tray" on the outdoor unit and during the time is carried up the heat exchanger.

The installation of an air conditioning split type system is a complex activity. One of the important operations is "vacuumization of the system”. This is a test with which it is checked whether the system is sealed,because if the system is not sealed,so the Freon will lead and this will cause a serious accident. The second part of the vacuuming includes bringing out of the system the air and also the humidity,which is extremely important condition for the proper operation of the air conditioning system.

Practically this is not possible. The solar collectors can take between 10% and 30% of the heating needs of buildings insulated by the current standards. Basically no matter how many collectors you install, there are fully cloudy days in the coldest months when you will absolutely need a conventional source of energy.

Because the Freon who runs in the system has no smell, one of the usual source of that can be accumulated molds and fungi in the indoor unit as a result of irregular maintenance.

At start in heating mode the air conditioner first checks the temperature of the freon in the system and adapts it to the required temperature for operation. The lower the outdoor temperature is, the longer it takes the conditioner to service itself. At restart the protective mechanism stops the compressor for about 3 minutes to prevent overloading of the system. Wait 3 minutes and the air conditioner must start working automatically.

At sudden cooling of air with high humidity water condensation is formed over the indoor unit. At self-defrost of the outdoor unit it is possible to release water vapor.

When operating in cooling mode the indoor unit condensates, as the installation team brings this condensation outside to a convenient location for disposal. In heating mode the outdoor unit condensates and the condensation is brought to a convenient drain location.

WARNING! Long condensation lines in heating mode, i.e. when the temperatures outside are low, lead to a precondition of freezing of the water in them, which leads to leakage from random locations of the outdoor unit tray. Water is formed in the outdoor unit also during self-defrost.

If your air conditioner is in the bedroom or under the window of neurotic neighbors, you will surely think about how loud it is. For most domestic air conditioners the level of noise from the indoor unit is in the range of 21-36 dB, while the outdoor unit's rate is from 38 to 56 dB, which is the same level of noise of that in an office or on the street. If you have requirements for low noise, you should consider that air conditioners have several modes of work and you can not control the noise from air flowing through the fan. However, if you still want to be aware of the noise before purchasing, visit HVAC companies and ask the staff to demonstrate different models.