Central Air Conditioning

Central Air ConditioningCentral Air Conditioning - Almost all of us have experienced air conditioning but few people understand exactly how and why it works. Most homes have central air conditioners which are often referred to as split systems or central systems. This means that there is a separate outdoor and indoor unit with copper tubing which connects the two transferring the refrigerant between the two units.

An air conditioner is designed to take heat out of your home and transfer it outside.The cooling medium your system uses is called refrigerant. The outside unit consists of three main components; a condensing coil, a compressor and a fan or blower. The inside unit has two main components: an evaporator coil, and a fan which usually is a part of your furnace or gas fired heaters. The compressor in your outdoor unit compresses the refrigerant or Refrigerant into a high temperature, high pressure gas. This packs the molecules of the refrigerant closer together creating more energy and temperature per square inch. As that superheated gas flows through the outdoor coil the fins act like a radiator and quickly begins to dissipate the heat. Air from the outdoor fan blows across these fins and it loses some of its heat. As it cools it condenses and transforms from a gas to a liquid which is usually just 10 degrees above the outdoor temperature.

This cooler liquid refrigerant travels through a sealed copper tube and into the indoor or evaporator coil. The liquid then goes through a very tiny hole or metering device causing the liquid's pressure to drop significantly. This causes the refrigerant to expand which turns it into a low temperature, low pressure gas. By spreading out the molecules the temperature of the gas drops to just above freezing. This gas then absorbs heat from the air traveling across the coil which is pulled in through the return air and into a sealed duct system by the indoor fan. From there the cooler air passes back out to the supply ducts which blow the cool air throughout your house and into individual rooms. In the process of cooling the air heat is absorbed back into the refrigerant. The heated refrigerant is then carried back outside through another copper tube and is compressed again which starts the process over. No cooling is created in this process. Since energy can be neither created or destroyed, heat is simply rerouted to the outside of the home where it is no longer a nuisance.

Central Air Conditioning systemAn air conditioner not only cools the air but adds to the comfort level by dehumidifying or taking the moisture out of the air. Moisture condenses on the indoor coil like it does on the outside of a glass of ice water on a hot, humid day. As the warm air passes over the coil and is cooled it can't hold the same amount of moisture. The extra moisture is then carried away through a drain and into a septic system or water trap. Sometimes the drain lines may become clogged which can result in water leaks in your ceiling or walls. An annual air conditioning inspection is a great way to keep your system is running smoothly and to keep drains clean.

This process continues until the room reaches the temperature set on the thermostat. The thermostat then senses it and turns off the air conditioner until the room warms up, and the cycle begins again.

To keep the coils clean the filter remove dust and other contaminants from the air. Dirty coils cause your system to use more energy and can shorten the life of your unit. Once again an annual air conditioning inspection will help keep your system is running efficiently and cut down on expensive repairs.

One of the most important things to consider when purchasing a unit is the efficiency or SEER. The higher the efficiency of the unit the more it will cost you in the beginning but an investment in a higher efficiency system will return your investment many times over in cost savings over the course of the equipments life span. Air conditioner efficiency is rated in SEER or Seasonal Energy Efficiency Rating. SEER ratings tell you how much cooling you get back for a unit of electricity so the higher the number the more you get for your money. Before 1992 most units manufactured were at a 6.0 SEER rating. Today the lowers efficiency unit you can buy is a 10.0 and high efficient units start at 12.0. If you replaced a unit that was rated at 6.0 with a 12.0 you would save half of the cost of the electricity to run the unit. Two speed units can run on low speed 80% of the time which allow them to get ratings as high as 16.0+ SEER.

For more information on choosing an air conditioning system click here.

central air conditionerAir conditioners come in many types and options.

Two speed units can run on low speed up to 80% of the time, which uses less electricity than a conventional unit. Two speed units run for longer cycles at low speed and translate into fewer on and off cycles resulting in smaller temperature swings for more stable even cooling.

Heat pumps work much like a conventional air conditioner cooling the air during the hot summer months. They also contain a reversing valve which reverses the flow of Refrigerant in the winter to effectively creating a heating system to keep you warm in the winter months.


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Ra-Jac Air Conditioning & Heating has proudly served Galveston County TX since 1966. We pride ourselves on providing top notch service on residential and commercial air conditioning, heating, and refrigeration in the Southern Texas area.


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