Energy Saving Central Air Conditioning 
 2.1 The existing problems in central air conditioning 
 Frozen pump with central air conditioning system. Human depending on the season decided to run the pump station number, start the way most of the Star - Triangle Buck started. Work the pump has been operating frequency, temperature changes will not deceleration, energy waste. Pump directly to the impact of starting large equipment, motor bearing wear big, so large amount of maintenance work. 
 Cooling fan will not work once the ambient temperature changes deceleration, energy waste. 
 2.2 Analysis of Energy Saving Central Air Conditioning System 
 Central air conditioning is a large shopping centers, hotels, supermarkets, offices, factories, and many other places where electricity consumption the largest unit, the total electricity costs, only the central air conditioning to account for 60%, so the central air-conditioning energy saving becomes particularly important. But saving is not renewable energy, but to improve energy efficiency, energy saving must be a saving of space there. Central air conditioning in the design and selection of equipment is usually the highest temperature according to the local weather history, to design, and left 15 to 20% margin, meaning that even in the hottest season, air-conditioning is also a margin (individual special exceptions), this part of the margin for the design margin. In addition, the need for air conditioning of the year several months, the temperature difference is also great, such as the May and August air conditioning air conditioning compared to May there is a greater margin, as shown in Figure 1 :. According to authoritative investigation and analysis of more than 90% of the country is basically run the central air-conditioning load in 70% less than the time difference into account seasonal variations and changes in temperature factors greater space saving. . Facts have proved that by freezing the rationalization of the pump and cooling pump control not only the circulatory system itself can save 30 ~ 60%, and can indirectly promote the host 5 to 10% energy saving. Central air conditioning system in the circulatory system, cooling pumps and pump frozen except for a few small models, the majority of multi-pump, with the weather and start a different number of pumps, namely: to open up the pump at high temperatures, low temperatures less pump, the surface energy-saving measures have been taken, but in some cases there is no way to solve, such as the opening of a waste of two pumps in the pump is not enough to open the issue, open 0.7 pumps can meet the situation, but only to open a pump caused by waste. Central air conditioning with chilled water energy system is out of the water and cooling water temperature is controlled based on the frozen pump, cooling fan pump and air supply system for variable frequency control, the central air conditioning system is always running in top shape, so as to achieve Festival electrical purposes.