Personal Air-Conditioners

Old ON/OFF and the New all DC Inverter 

Will compaire the tehnologies and the technologigal benifits, the instalation precutions for safty and energy efficiency and finaly the health risks and precautions....

a litle bit of history

The creation of the modern electrical air conditioning unit is credited to the American inventor Willis H. Carrier. After graduating from Cornell University, The first air conditioner was designed and built in Buffalo, New Yok by Carrier and began working on 17 July 1902.   Many years later Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet the rising demand. Over time, air conditioning came to be used to improve comfort in homes and automobiles as well. Residential sales expanded dramatically in the 1950s.


In 1945, Robert Sherman of Lynn, Massachusetts invented a portable, in-window air conditioner that cooled, heated, humidified, dehumidified, and filtered the air.  Since then many improuvments have been done to this original design still popular in USA but becase it ocupied the window space and created safty issues is not that popular in other countries. Newer designs of Split units (wall , duct, seling mount ) are now available in almost every country because of their versability.


Air conditioning (often referred to as AC, A/C, or Air Con) is the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioning can be used in both domestic and commercial environments. This process is most commonly used to achieve a more comfortable interior environment, typically for humans and other animals; however, air conditioning is also used to cool and dehumidify rooms filled with heat-producing electronic devices, such as computer servers, power amplifiers, and to display and store some delicate products, such as artwork.
Air conditioners often use a fan to distribute the conditioned air to an occupied space such as a building or a car to improve thermal comfort and indoor air quality. Electric refrigerant-based AC units range from small units that can cool a small bedroom, which can be carried by a single adult, to massive units installed on the roof of office towers that can cool an entire building. The cooling is typically achieved through the refrigeration cycle, but sometimes evaporation or free cooling is used. Air conditioning systems can also be made based on desiccants (chemicals which remove moisture from the air). Some AC systems reject or store heat in subterranean pipes.

  • Old ON/OFF Systems  - Personal Air-Condition for many years where Not energy eficient and their motors (Compresor, fans,etc)  and had two states of operation eather working (ON) or not working(OFF) nothing in between! As technology was evolving and the first DC compesors was created we start seeing a hibird system with only a DC compresor.
  • New all DC Inverter Systems  - In the newest Designs  manufactures equipt their  Air-Conditions with all DC inverter Type motors (Compresor, fans,etc) and with sofisticated electronics and functions considering many enviromental paramiters succesfuly provide steady temperatures whyle saving a lot of energy.  Different manufucturs distinquice themselves by providing more energy eficiency, better preformance at extreem weather contitions, lower operating noise, faster riching the desired temperature, different cleaning air technologies and self cleaning technologies. More details here!
  • The Marketing difference -  If you wher lets say to compaire two split air-conditions of 12000BTU each, one economical and a second one double its price certenly they can't be of same quality but why marketers market them as one of the same? Simply to confuse the buyer!! An Educated buyer will always read the manual of each air-condition and there should be able to find the diference. To try symplyfy this fake marketing similarity I would use the foloing example: compairing two cars a cheap car and a ferrari, both cars say that can reach the 100 m barier but they dont mention the how fast they will reach it.   Ferary will do the 100 in 5 second and the cheap car will do it also but in 20 sec.  More details here!
  • Energy eficiency- a key ingredient to energy efficiency is the proper instalation, to do this right its important to consider two facors after first reading the manual! a) what is the refrigirant used and how may meteres of piping is sugeststo be the manufacture  to be used in the instalation in order to get the expected results from the aircondition we have purchused. Newer refrigirant R32 now comonly used in all personal Air-conditions (Warning it is Flamable) and requires special consideration  for safty first and then energy efficiency!  In split Residential instalions for safety is sugested a minimum 3 meters of piping and this length may also be enaugh for the more expencive air-condition to meet energy eficiency but for the more economical air-condition a 5-7m piping may be required!  Every instalation has is own requiremes but in general Longer pipes always  within the munufactures specs provide usaly better energy efficiency results!
  • Having said that a lot of non profesionals do intalations with less than a meter of piping! Very dangerus becace you are not only loose the energy eficiency of your unit but in R32 instalations you allow (not knowing) someone to instal in your home a ticking Bomb!! That is why you yourself have to read the manual especialy in R32 Instalations and demand exactly what the manufacture sugest in piping length for your Air-condition and not sorter pipes you often see and get with a free install package with the purchused of your unit. Wjrong instalations could result to this read more here!

Most popular models  

  • Window unit and packaged terminal - Window unit air conditioners are installed in an open window. The interior air is cooled as a fan blows it over the evaporator. On the exterior the heat drawn from the interior is dissipated into the environment as a second fan blows outside air over the condenser. A large house or building may have several such units, allowing each room to be cooled separately.
  • Split systems   - Split-system air conditioners come in two forms: mini-split and central systems. In both types, the inside-environment (evaporative) heat exchanger is separated by some distance from the outside-environment (condensing unit) heat exchanger. 
  • Mini-split (ductless) system - A mini-split system typically supplies air conditioned and heated air to a single or a few rooms of a building. Multi-zone systems are a common application of ductless systems and allow up to 8 rooms (zones) to be conditioned from a single outdoor unit. Multi-zone systems typically offer a variety of indoor unit styles including wall-mounted, ceiling-mounted, ceiling recessed, and horizontal ducted. Mini-split systems typically produce 9,000 to 36,000 Btu (9,500–38,000 kJ) per hour of cooling. Multi-zone systems provide extended cooling and heating capacity up to 60,000 Btu's. Large systems are known as VRF (Variable refrigerant flow) systems. Mini split ductless systems were invented by Daikin in 1973, and VRF systems were also invented by Daikin in 1982. Advantages of the ductless system include smaller size and flexibility for zoning or heating and cooling individual rooms. The inside wall space required is significantly reduced. Also, the compressor and heat exchanger can be located farther away from the inside space, rather than merely on the other side of the same unit as in a PTAC or window air conditioner. Flexible exterior hoses lead from the outside unit to the interior one(s); these are often enclosed with metal to look like common drainpipes from the roof. In addition, ductless systems offer higher efficiency, reaching above 30 SEER. The primary disadvantage of ductless air conditioners is their cost. Such systems cost about US$1,500 to US$2,000 per ton (12,000 BTU per hour) of cooling capacity. This is about 30% more than central systems (not including ductwork) and may cost more than twice as much as window units of similar capacity. An additional possible disadvantage is that the cost of installing mini splits can be higher than some systems. However, lower operating costs and rebates or other financial incentives—offered in some areas—can help offset the initial expense. 
  • Multi-split system  - A multi-split system is a conventional split system, which is divided into two parts (evaporator and condenser) and allows cooling or heating of several rooms with one external unit. In the outdoor unit of this air conditioner there is a more powerful compressor, ports for connecting several traces and automation with locking valves for regulating the volume of refrigerant supplied to the indoor units located in the room. A large Multi Split System is called a Variable refrigerant flow system and can be used instead of a central air conditioner system, as it allows for higher energy efficiency but it is more expensive to purchase and install. 
  • Difference between split system and multi-split system - Other common types of air conditioning system are multi-split systems, the difference between separate split system and multi-split system in several indoor units. All of them are connected to the main external unit, but the principle of their operation is similar to a simple split-system. Its unique feature is the presence of one main external unit that connected to several indoor units. Such systems might be the right solution for maintaining the microclimate in several offices, shops, large living spaces. Just few of outdoor units do not worsen the aesthetic appearance of the building.The main external unit can be connected to several different indoor types: floor, ceiling, cassette, etc. 
  • Multi-split system installation considerations - Before selecting the installation location of air conditioner, several main factors need to be considered. First of all, the direction of air flow from the indoor units should not fall on the place of rest or work area. Secondly, there should not be any obstacles on the way of the airflow that might prevent it from covering the space of the premises as much as possible. The outdoor unit must also be located in an open space, otherwise the heat from the house will not be effectively discharged outside and the productivity of the entire system will drop sharply. It is highly advisable to install the air conditioner units in easily accessible places, for further maintenance during operation.  The main problem when installing a multi-split system is the laying of long refrigerant lines for connecting the external unit to the internal ones. While installing a separate split system, workers try to locate both units opposite to each other, where the length of the line is minimal. Installing a multi-split system creates more difficulties, since some of indoor units can be located far from the outside. The first models of multi-split systems had one common control system that did not allow you to set the air conditioning individually for each room. However, now the market has a wide selection of multi-split systems, in which the functional characteristics of indoor units operate separately from each other.  The selection of indoor units has one restriction: their total power should not exceed the capacity of the outdoor unit. In practice, however, it is very common to see a multi-split system with a total capacity of indoor units greater than the outdoor capacity by at least 20%. However, it is wrong to expect better performance when all indoor units are turned on at the same time, since the total capacity of the whole system is limited by the capacity of the outdoor unit. Simply put, the outdoor unit will distribute all its power to all operating indoor units in such a way that some of the rooms may not have a very comfortable temperature level. However, the calculation of the total power is not simple, since it takes into account not only the nominal power of the units, but also the cooling capacity, heating, dehumidification, humidification, venting, etc
  • Portable units - A portable air conditioner can be easily transported inside a home or office. They are currently available with capacities of about 5,000–60,000 BTU/h (1,500–18,000 W) and with or without electric-resistance heaters. Portable air conditioners are either evaporative or refrigerative. 

Energy transfer
In a thermodynamically closed system, any power dissipated into the system that is being maintained at a set temperature (which is a standard mode of operation for modern air conditioners) requires that the rate of energy removal by the air conditioner increase. This increase has the effect that, for each unit of energy input into the system (say to power a light bulb in the closed system), the air conditioner removes that energy. To do so, the air conditioner must increase its power consumption by the inverse of its "efficiency" [coefficient of performance or COP (sometimes CP or CoP)] times the amount of power dissipated into the system. As an example, assume that inside the closed system a 100 W heating element is activated, and the air conditioner has a coefficient of performance of 200%. The air conditioner's power consumption will increase by 50 W to compensate for this, thus making the 100 W heating element cost a total of 150 W of power.

It is typical for air conditioners to operate at "efficiencies" of significantly greater than 100%. However, it may be noted that the input electrical energy is of higher thermodynamic quality (lower entropy) than the output thermal energy (heat energy).

Air conditioner equipment power in the U.S. is often described in terms of "tons of refrigeration", with each approximately equal to the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period. The value is defined as 12,000 BTU per hour, or 3517 watts. Residential central air systems are usually from 1 to 5 tons (3.5 to 18 kW) in capacity.

Seasonal energy efficiency ratio
Main article: Seasonal energy efficiency ratio
For residential homes, some countries set minimum requirements for energy efficiency. In the United States, the efficiency of air conditioners is often (but not always) rated by the seasonal energy efficiency ratio (SEER). The higher the SEER rating, the more energy efficient is the air conditioner. The SEER rating is the BTU of cooling output during its normal annual usage divided by the total electric energy input in watt hours (W·h) during the same period.

SEER = BTU ÷ (W·h)
this can also be rewritten as:

SEER = (BTU / h) ÷ W, where "W" is the average electrical power in Watts, and (BTU/h) is the rated cooling power.
For example, a 5000 BTU/h air-conditioning unit, with a SEER of 10, would consume 5000/10 = 500 Watts of power on average.

The electrical energy consumed per year can be calculated as the average power multiplied by the annual operating time:

500 W × 1000 h = 500,000 W·h = 500 kWh
Assuming 1000 hours of operation during a typical cooling season (i.e., 8 hours per day for 125 days per year).

Another method that yields the same result, is to calculate the total annual cooling output:

5000 BTU/h × 1000 h = 5,000,000 BTU
Then, for a SEER of 10, the annual electrical energy usage would be:

5,000,000 BTU ÷ 10 = 500,000 W·h = 500 kWh
SEER is related to the coefficient of performance (COP) commonly used in thermodynamics and also to the Energy Efficiency Ratio (EER). The EER is the efficiency rating for the equipment at a particular pair of external and internal temperatures, while SEER is calculated over a whole range of external temperatures (i.e., the temperature distribution for the geographical location of the SEER test). SEER is unusual in that it is composed of an Imperial unit divided by an SI unit. The COP is a ratio with the same metric units of energy (joules) in both the numerator and denominator. They cancel out, leaving a dimensionless quantity. Formulas for the approximate conversion between SEER and EER or COP are available.[39]

(1) SEER = EER ÷ 0.9
(2) SEER = COP × 3.792
(3) EER = COP × 3.413
From equation (2) above, a SEER of 13 is equivalent to a COP of 3.43, which means that 3.43 units of heat energy are pumped per unit of work energy.

The United States now requires that residential systems manufactured in 2006 have a minimum SEER rating of 13 (although window-box systems are exempt from this law, so their SEER is still around 10).

  • Automobile power consumption
  • In an automobile, the A/C system will use around 4 horsepower (3 kW) of the engine's power, thus increasing fuel consumption of the vehicle.[62]
  • Refrigerants
  • The selection of the working fluids (refrigerants) has a significant impact not only on the performance of the air conditioners but on the environment as well. Most refrigerants used for air conditioning contribute to global warming, and many also deplete the ozone layer.[63] CFCs, HCFCs, and HFCs are potent greenhouse gases when leaked to the atmosphere.
  • The use of CFC as a refrigerant was once common, including the refrigerants R-11 and R-12 (sold under the brand name Freon-12). Freon refrigerants were commonly used during the 20th century in air conditioners due to their superior stability and safety properties. When they are released accidentally or deliberately, these chlorine-bearing refrigerants eventually reach the upper atmosphere.[64] Once the refrigerant reaches the stratosphere, UV radiation from the Sun homolytically cleaves the chlorine-carbon bond, yielding a chlorine radical. These chlorine radicals catalyze the breakdown of ozone into diatomic oxygen, depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst until it binds with another radical, forming a stable molecule and quenching the chain reaction.
  • Prior to 1994, most automotive air conditioning systems used R-12 as a refrigerant. It was replaced with R-134a refrigerant, which has no ozone depletion potential. Old R-12 systems can be retrofitted to R-134a by a complete flush and filter/dryer replacement to remove the mineral oil, which is not compatible with R-134a.
  • R22 (also known as HCFC-22) has a global warming potential about 1,800 times higher than CO2.[65] It was phased out for use in new equipment by 2010, and is to be completely discontinued by 2020. Although these gasses can be recycled when air conditioning units are disposed of, uncontrolled dumping and leaking can release gas directly into the atmosphere.
  • In the UK, the Ozone Regulations[66] came into force in 2000 and banned the use of ozone depleting HCFC refrigerants such as R22 in new systems. The Regulation banned the use of R22 as a "top-up" fluid for maintenance between 2010 (for virgin fluid) and 2015 (for recycled fluid). This means that equipment that uses R22 can still operate, as long as it does not leak. Although R22 is now banned, units that use the refrigerant can still be serviced and maintained.
  • The manufacture and use of CFCs has been banned or severely restricted due to concerns about ozone depletion (see also Montreal Protocol).[67][68] In light of these environmental concerns, beginning on November 14, 1994, the U.S. Environmental Protection Agency has restricted the sale, possession and use of refrigerant to only licensed technicians, per rules under sections 608 and 609 of the Clean Air Act.[69]
  • As an alternative to conventional refrigerants, other gases, such as CO2 (R-744), have been proposed.[70] R-744 is being adopted as a refrigerant in Europe and Japan. It is an effective refrigerant with a global warming potential of 1, but it must use higher compression to produce an equivalent cooling effect.[citation needed]
  • In 1992, a non-governmental organization, Greenpeace, was spurred by corporate executive policies and requested that a European lab find substitute refrigerants. This led to two alternatives, one a blend of propane (R290) and isobutane (R600a), and one of pure isobutane.[22][26] Industry resisted change in Europe until 1993, and in the U.S. until 2011, despite some supportive steps in 2004 and 2008 (see Refrigerant Development above).[31][71]



a litle bit of history

Health effects
In hot weather, air conditioning can prevent heat stroke, dehydration from excessive sweating and other problems related to hyperthermia. Heat waves are the most lethal type of weather phenomenon in developed countries. Air conditioning (including filtration, humidification, cooling and air disinfection) can be used to provide a clean, safe, hypoallergenic atmosphere in hospital operating rooms and other environments where proper atmosphere is critical to patient safety and well-being. It is sometimes recommended for home use by people with allergies.[citation needed]
Poorly maintained water cooling towers can promote the growth and spread of microorganisms such as Legionella pneumophila, the infectious agent responsible for Legionnaires' disease. As long as the cooling tower is kept clean (usually by means of a chlorine treatment), these health hazards can be avoided or reduced. The state of New York has codified requirements for registration, maintenance, and testing of cooling towers to protect against Legionella.