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How Your Air Conditioner Works
Air conditioning is the conditioning of air within a defined space. Conditioning usually involves heating or cooling, humidifying or dehumidifying, and filtering air. Central air conditioners cool and dehumidify a defined space. Heating is accomplished by an add-on to the system (such as an electric heat strip) or by a seperate unit (such as a furnace).
Central air conditioners are split systems: an outdoor unit (the condensing unit) and an indoor unit (air handler). The function of an air conditioner is to transport heat from one station to another. The vehicle your system uses to carry the heat is called a refrigerant.
The compressor in your outdoor unit converts the refrigerant into a high temperature, high pressure gas. As that gas flows through the outdoor coil, it loses heat and condenses into a high temperature, high pressure liquid. This liquid refrigerant travels through copper tubing into the evaporator coil. There the refrigerant expands. Its sudden expansion turns the refrigerant into a low temperature, low pressure gas. This gas then absorbs heat from the air circulating in the duct work. The cooled air is then distributed back through your house or place of business. Meanwhile, the heat absorbed by the refrigerant is carried back outside through copper tubing and released into the outside air.
Dirty coils and improper refrigerant levels can cause your system to cool less efficiently than it should. An inefficient system means higher energy bills. It also forces your compressor to work harder than is necessary and can actually shorten the life span of your unit. An annual air conditioning inspection by an experienced technician includes an inspection of the coils and the checking of your refrigerant charge, to insure that your system is running efficiently.
As the warm air circulating through your ducts passes over the evaporator coil, it is quickly cooled and can no longer hold as much moisture as it did at a higher temperature. The excess moisture condenses on the outside of the coils and is carried away through a drain. The process is similar to what happens when moisture condenses on the outside of a glass of ice water on a hot, humid day.
Occassionally, the drain lines may become clogged and your system will not drain properly. This can result in a drain pan overflow, leading to water leaks in your ceiling or walls. An annual air conditioning inspection by an experienced technician should include an inspection of your drain lines and an algaecide treatment to retard the growth of algae. Consider having a float switch installed in your unit's drain pan. This switch will help to prevent water damage by shutting off your air conditioner should water back up in the pan.
Heat PumpsA heat pump cools your home or place of business by extracting heat from indoor air and forcing (pumping) the heat outdoors. For diagrams and a more detailed description on how heat pumps work, visit our Heat Pumps web page.
The Importance of an Annual Cooling Inspection
Would you drive a car year after year without ever changing the oil or taking it to a mechanic for a tune-up? Probably not. Like your car, your cooling and heating systems must be maintained in order to run efficiently and dependably. An annual cooling check-up allows a technician to identify minor problems before they become major ones. ACU Air performs annual cooling system inspections from March 1st through May 15th, weather permitting. (Ideally the outdoor temperature should be in the high sixties or above to get an accurate refrigerant pressure reading. Also, the outside condenser unit cannot be opened and inspected when it is raining).
Glossary
- AFUE
- Annual Fuel Utilization Efficiency. A measure of a furnace's heating efficiency. The higher the AFUE percentage, the more efficient the product. The US government's established minimum AFUE rating for furnaces is 78%.
- Air Handler
- Also known as the "indoor unit", the air handler is the evaporator section of your air conditioning system. It circulates and delivers the cooled air. The indoor unit contains the evaporator coil, an indoor fan motor and, sometimes, a heat strip (for supplemental heating).
- Automatic Setback Thermostat
- An automatic setback thermostat or programmable thermostat allows you to store six or more separate temperature settings for different times of the day. You can set the thermostat with a daily or weekly program. And you can override the settings at any time without affecting the daily or weekly program.
- BTU
- BTU stands for British Thermal Unit: the amount of heat required to raise the temperature of one pound of water one degree fahrenheit.
- Compressor
- The compressor is the "engine" which drives the condensing unit. The condensing unit serves as a pump which compresses the gas in the high pressure (condensing) side of the cooling cycle and causes the refrigerant (Freon) to circulate.
- Condensing Unit
- Also known as the "outdoor unit", the condensing unit pumps vaporized refrigerant from the air handler (indoor unit), compresses it, liquefies it, and returns it. It contains the compressor coil, an outdoor fan motor, refrigerant control valves, and other necessary controls.
- EER Rating
- More accurate here in Texas than the more commonly used SEER rating, the Energy Efficiency Ratio is the ratio of BTU's used for cooling to the total amount of electrial power measured in watts to cool a home down to eighty degrees when the outdoor temperature is ninety-five degrees. Ask an AC technician for the EER rating on a new air conditioning unit and you may not get a straight answer. This is because the EER rating of an air conditioning unit varies depending on the efficiency of the other units it is being matched with.
- Evaporator Coil
- Found inside the air handler (indoor unit), the evaporator is where refrigerant vaporizes and absorbs heat.
- Refrigerant
- Refrigerant is a substance which absorbs heat by changing states (evaporating) from liquid to gas. It releases heat by changing states (condensing) from gas back to liquid. Most people refer to the refrigerant used in cooling systems as Freon (DuPon'ts brand name for R22) and Puron (a brand name for R410A). Because of its potentially damaging affect on the environment, the purchase and use of refrigerants is strictly regulated by the Environmental Protection Agency (EPA). To legally buy and use R22 and R410A, an air conditioning technician must own a recovery unit and must be EPA certified. Removing Freon without a recovery unit destroys ozone and is a violation of federal law.
- SEER
- Seasonal Energy Efficiency Ratio is the ratio of BTU's used for cooling to the total amount of electrial power measured in watts (Annual Cooling in BTU's/Total Watt Hours = SEER). Theoretically this ratio is supposed to represent normal annual cooling to electrical power. However, the test used to measure SEER ratings is anything but normal for southeast Texas. The SEER rating measures the amount of energy used to cool a home down to eighty degrees when the outdoor temperature is eighty-two degrees. The EER rating is actually more accurate when it comes to Texas climatic conditions. As a general rule, the higher the SEER rating, the better the energy efficiency.
- Split System
- A split air conditioning system allows the air handler to be installed in a different location from the condenser. While split systems generally cost more to install than package units, they can save you money in the long run because they are more energy efficient. Another advantage is the reduction of condenser noise. Split systems are also often used where there is a space problem. Ask your ACU Air technician if a split system is right for you.
- Thermostat
- A temperature-sensitive switch that controls your heating and cooling systems. When the indoor temperature drops below or rises above the selected temperature setting, the switch moves to the "on" position, and your heater or air conditioner runs to warm or cool.
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Energy Saving Tips
How Your Air Conditioner Works
How Your Heater Works
How Your Heat Pump Works
Selecting an Air Conditioner
Selecting a Heater
Things to Check When Your Air Conditioner Isn't Cooling
Controlling Mold
The Woodlands GREEN
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