How Your Air Conditioner
Works
Air conditioning is the conditioning
of air within a defined space, usually a residence or a place of
business. Conditioning usually involves heating
or cooling, humidifying or dehumidifying,
and filtering
or cleaning air. If you have a central air conditioner, your
system cools and dehumidifies the defined space. Heating is
accomplished by an add-on to the system (such as an electric
heat strip) or by a separate 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, commonly
referred to as Freon.
The compressor in your
outdoor unit changes the refrigerant (or
"Freon") 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 a licensed 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.
Occasionally, 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 a licensed
technician includes an inspection of your draining system.
During the inspection, the technician will treat your draining
system with an algaecide to retard the growth of algae, which
can clog your system.
Your cooling system consists of an outdoor
unit (the condensing unit) and an indoor unit
(air handler). These two components are
designed to work together as a coordinated team to provide top
performance, maximum efficiency, and comfort. Whenever you
install a new outdoor unit, you should install a new, equally
efficient "matched" indoor unit at the same time.
While replacing the outdoor unit only may initially offer you
the lowest price, it may prove more expensive over time. When
your air conditioning components don't match, your system may
still work, but it won't perform at the promised energy
efficiency. In fact, your system could be up to 15% less
efficient than stated. You may be sacrificing comfort, as well,
as a mismatched system may have difficulty keeping up on the
hottest days. Finally, if your cooling system's components
aren't matched, it could create undue stress on your cooling
system, resulting in unnecessary, premature failure.
Heat Pumps
A heat pump cools your home or place of
building by extracting heat from indoor air and forcing
(pumping) the heat outdoors.
If your home or business uses a heat pump,
make sure that your heating and air conditioning technician is
certified to work on heat pumps before he services your unit.
Heat pumps operate on different principals than traditional
furnaces and air conditioners and so are engineered differently.
Not all state licensed heating and air conditioning technicians
are qualified to service heat pumps. To receive heat pump
certification, a technician must receive formal training in heat
pump design and repair and must pass a test administered by the Refrigeration
Service Engineers Society (RSES).
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.
Glossary
- 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.
- Evaporator
- 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 (R-22) as Freon. But this is
actually DuPont's brand name for R-22. The scientific name
for R-22 (or Freon) is halogenated chloroflourocarbon (CFC).
Because of its destructive effect on the ozone, the use of
R-22 is strictly regulated by the Environmental
Protection Agency (EPA). To legally buy and use Freon,
an air conditioning technician must own a recovery
unit and must be certified EPA certified.
Unfortunately, many EPA certified technicians do not always
use their recovery units when releasing Freon from a unit.
Removing Freon without a recovery unit destroys ozone and is
a violation of federal law. You should check carefully with
any technician you use about how he handles the refrigerants
in your system, since misuse can result in costly
fines.
- SEER
- Seasonal Energy
Efficiency Ratio is the
efficiency rating for air conditioning units. The higher the
SEER rating, the better the energy efficiency. SEER is the
ratio of the amount of BTU's used for
cooling in normal annual use to the total amount of electrical
power (measured in watts) over the same period. (Annual
Cooling in BTU's/Total Watt Hours = SEER).
- 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.
- 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.
- Zoning Systems
- A zoning system allows the home or
business owner to control the environment in an
individualized and energy efficient way. The residence or
place of business can be divided into 2 or more zones.
Through the use of fully modulating dampers, the system can
selectively cool or heat certain portions of the building at
given periods of the day. With some systems, indoor humidity
can likewise be displayed and controlled. A popular
alternative to zoning is having two or more units in a
larger building. Each unit controls the temperature and
humidity in a given portion of the building. Consult with an
air conditioning design contractor to determine which
of these systems would best meet your needs.
-
Schneider
Heating, Inc.
252 Pillow Street
Butler PA 16001
724-283-8525
© Schneider
Heating Inc. 2002
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