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1.Approximately how many hours per year you will be operating the unit 2.How much a kilowatt-hour (kWh) costs in your area Let's say that you plan to use the air conditioner in the summer (four months a year) and it will be operating about six hours a day. Let's also imagine that the cost in your area is $0.10/kWh. The difference in energy consumption between the two units is 200 watts, which means that every five hours the less expensive unit will consume 1 additional kWh (and therefore $0.10 more) than the more expensive unit. Assuming that there are 30 days in a month, you find that during the summer you are operating the air conditioner: Since the more expensive unit costs $100 more that means that it will take about seven years for the more expensive unit to break even. See this page for a great explanation of seasonal energy efficiency rating (SEER). Split-system Units A split-system air conditioner splits the hot side from the cold side of the system。 The cold side, consisting of the expansion valve and the cold coil, is generally placed into a furnace or some other air handler. The air handler blows air through ducts. The hot side known as the condensing unit, lives outside the building. The unit consists of a long, spiral coil shaped like a cylinder. Inside the coil is a fan, to blow air through the coil, along with a weather-resistant compressor and some control logic. This approach has evolved over the years because it is low-cost, and also because it normally results in reduced noise inside the house (at the expense of increased noise outside the house). Besides the fact that the hot and cold sides are split apart and the capacity is higher (making the coils and compressor larger), there is no difference between a split-system and a window air conditioner. In warehouses, businesses, malls, large department stores, etc., the condensing unit normally lives on the roof and can be quite massive. Alternatively, there may be many smaller units on the roof, each attached inside to a small air handler that cools a specific zone in the building. Let's take a look now at a chilled-water air conditioner. Chilled-water System In larger buildings and particularly in multi-story buildings, the split-system approach begins to run into problems. Either running the pipe between the condenser and the air handler exceeds distance limitations (runs that are too long start to cause lubrication difficulties in the compressor), or the amount of duct -work and the length of ducts become unmanageable. At this point, it is time to think about a chilled-water system. In a chilled-water system, the entire air conditioner lives on the roof or behind the building. It cools water to between 40 and 45 F (4.4 and 7.2 C). This chilled water is then piped throughout the building and connected to air handlers as needed. There is no practical limit to the length of a chilled-water pipe if the system can be got well - insulated. Whenever you walk behind a building and find a unit that has large quantities of water running through a plastic mesh, you will know you have found a cooling tower! In many office complexes and college campuses, cooling towers and air conditioning equipment are centralized, and chilled water is routed to all of the buildings through miles of underground pipes. Based on dynamic load track central air-conditioning system entire closed loop energy conservation technology research. 1. introductions The energy conservation may say is the building character automatic control system starting point and the home to return to. It is well known, in the intelligent construction, HVAC (heating, ventilates and air conditioning) the system consumes to have to occupy the building consumption total energy enormous partial proportions, approximately about 50% ~60%. Specially cold: East the unit, the cooling tower, the circulating water pump and the air conditioning unit, the new atmosphere unit, all are consumes energy the big household. Therefore really has essential develops one effective air-conditioning system energy conservation method, especially uses is in improves in the existing building air-conditioning system automation the aspect. DDC (Directdigitalcontr01) the direct of numerical control, is a structure simple operation easy control device, it may borrow by the connection switches over the equipment to make the systems control along with the load change, like the air conditioning cold water circulatory system, the air conditioning box frequency conversion automatic amount of wind adjustment and the cooling tower radiation ventilator frequency conversion holds controls and so on, may let an air-conditioning system more effective revolution, like this, not only brings the very big economic efficiency for the estate management, moreover also may cause the system to move under a better operating mode, thus lengthens the equipment the service life as well as achieved provides goal of the comfortable air conditioning environment and the energy conservation. The general building commonly used air-conditioning system has CAV, VAV, VWV and so on, respectively has differently holds controls the way, all may use DDC to control. 1 decides the amount of wind system (ConstantAirVolume, is called CAV). Decides certainly the amount of wind system the amount of wind which blows out for the air conditioner certainly, provides coldly (is warm) the gas which the air conditioning region needs. When air conditioning region load variation, then changes the blast temperature to deal with in the room to shoulder, and achieves the maintenance indoor temperature to the comfortable area request.
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