A central air conditioning unit is a much more efficient and effective way to cool multiple rooms within a single building than using smaller individual air conditioners placed in each room. Central air conditioners distribute cooled air through ducts. In many cases, the unit is also used as a heating system to distribute warm air.
An indoor thermostat controls when the air conditioner kicks on. Once the temperature set by the thermostat has been reached, the air conditioning motor starts up and the conditioning process is begun when liquid refrigerant is cooled in the condenser coils.
The condenser unit is the part of the air conditioning system that is found outside. The placement of the condenser unit outside is done so for two reasons. The condenser unit creates a substantial amount of both noise and heat. The condenser fan that you can see through the grille in the top of the unit pulls air through condenser coils to dissipate this heat.
The compressor is located inside the condenser unit and its purpose is to pressurize vaporized refrigerant. This raises the temperature of the refrigerant as the compressor pumps it through the condenser coils. The refrigerant is cooled to a liquid within these cools before flowing through the evaporator coils that are located indoors. The refrigerant eventually returns to the compressor in vapor form.
Small diameter copper tubing is usually used to transport the refrigerant from the condenser to the evaporator found indoors. Some systems use a split line method of delivery in which liquid refrigerant flows through one line and refrigerant vapor runs through another.
The most common evaporator coil is an A-shaped system normally found at the top of the inside unit. This shape affords the coils the ability to get the largest amount of coils into the smallest available space. A drain pan is used to collect the water that condenses on the coil. A pipe is used to empty this pan and it is fitted with a trap that accomplishes two things. The drain pipe helps to insulate the air conditioner system against humid basement air in some places or it helps to present insect infestation of the coil in other homes.
A larger central air conditioning system does not necessarily mean a better or more efficient one. Size matters in terms of accuracy. An air conditioning unit that is too big will cycle over and over, according to “Reader’s Digest New Complete Do-It-Yourself Manual.” This can lead not only to inefficient cooling as well as reducing the life expectancy of the system’s compressor. Too large a system can also raise the level of humidity in your home.
Central air conditioning efficiency can be determined by checking the Seasonal Energy Efficiency Ratio (SEER) number. Systems with a higher number are more efficient, but they are also more expensive upfront. You need to take into consideration not only how high the SEER number is, but the number of hours that you actually need to use air conditioning per year to calculate whether the additional cost will be beneficial to you.