Air con
Air Con Principles
Employing the same principles as a home refrigerator,
air
conditioners cool with an evaporator, a cold indoor coil. The
collected heat outside is released by the condenser, a hot outdoor
coil. The evaporator and condenser coils consist of serpentine tubing
(usually made of copper) shrouded by aluminium fins.
The compressor
The air con compressor (which is essentially a pump)
moves the heat transfer fluid (or refrigerant) between the evaporator
and the compressor between the condenser and the evaporator. The
refrigerant is forced through the circuit of tubing and fins in
the coils by the pump and the liquid refrigerant evaporates in the
indoor evaporator coil which pulls heat out of the indoor air and
cools the home. Hot refrigerant gas is pumped into the condenser
outdoors, where it is reverted back to a liquid which gives up its
heat to the air that flows over the metal tubing and fins in the
air
con condenser.
The basic types of air
conditioner are split-system central air conditioners, room
air con and packaged central air conditioners. Rather than cool
the entire home, room air conditioners cool that specific room.
If used to provide cooling only where it is needed then room
air conditioners are more economical
to operate than central units, even though they offer a lower level
of efficiency than central air conditioners.
Domestic
air conditioners usually range between 5500 Btu per hour to
14,000 Btu per hour. National appliance standards generally require
new room
air conditioners to have a minimum EER of 8.5 and it is recommended
that you select a
domestic air conditioner with a minimum EER of 9.0 if you live
in a mild climate and a hot climate requires one with an EER of
over 10.
Air Con Costs
In a report by the Association Of Home Appliance Manufacturers,
it was stated that between 1972 and 1991, the average EER of room
air conditioners rose by 47%. By replacing a 1970’s vintage room
air conditioner with an EER of 5 with a new unit that has an EER
of 10, air conditioning costs will be cut in half.
How central air con works
Central
air con works by circulating cool air through a system of supply
and return ducts. These carry the cooled air from the air conditioner
to the home. As the cooled air circulates through the home it becomes
warmer and then it returns to the air conditioner through the return
ducts and registers. The two main types of central air conditioner
are split-system units and packaged units.
Split-system air con
With a split-system central air conditioner,
the compressor and condenser are contained in an outdoor metal cabinet
while the evaporator is stored in an indoor cabinet. With many split-system
air conditioners, the indoor cabinet also houses a furnace or a
part of the heat pump. The cabinet or main supply duct of this furnace
or heat pump also houses the air conditioners evaporator coil. A
split-system is the most economical air conditioner to install
in a home that has a furnace but no air conditioner.
Central Air Con
With a packaged central air conditioner
one cabinet houses the evaporator, condenser and compressor. This
is usually placed on a roof or concrete slab close to the house’s
foundation. This type of system is also used in small commercial
premises. A packaged air conditioner that has electric heating coils
or a natural gas furnace is a combination of air conditioner and
and central heater that elminates the need for a separate furnace
indoors.
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