So how do air conditioners work?
Air conditioners look and operate very much
like heat pumps with the notable exception that they provide
cooling only. While air conditioners and heat pumps do require
the use of some different components, they both operate on
the same basic principles. This section will explore five
topics to consider when you are looking at air conditioners.
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How They Work
Heat pumps and central air conditioners are "split systems,"
which means that there is an outdoor unit and an indoor unit.
The job of the heat pump or air conditioner is to transport
heat either into or out of your home. The "vehicle"
your system uses to carry the heat is called refrigerant.
For cooling operation, air from your home passes
through the indoor coil. Heat is absorbed from the indoor
air and the resulting cooler air is ciruclated back into your
home through your duct system. Heat from your home exits through
the outdoor coil.
While it’s keeping you cool, your air
conditioner or heat pump also works as an effective dehumidifier.
The process is similar to what happens when moisture condenses
on the outside of a glass of ice water on a hot, humid day.
For heating, a heat pump basically reverses
the cooling process to warm your home during cold weather.
Where does a heat pump get the heat to warm
your home when it’s cold outside? Even though 35 F air
may feel cold to humans, it actually contains a great deal
of heat. A heat pump’s heat exchanger can squeeze heat
out of cold air, then transfer that heat into your home with
the help of a fan coil or a furnace, which circulates the
warm air through your ducts.
Heat pumps are often installed with back-up
electric resistance heat or a furnace to handle heating requirements
when more heat is needed than the heat pump can efficiently
extract from the air. This option allows homeowners to enjoy
the energy-saving benefits of a heat pump and still maintain
comfortable indoor temperatures as outdoor temperatures gradually
Purchasing a brand name that has a reputation for quality
and reliability can save you headaches and extra expense down
Ask us about limited and extended warranties.
Some air conditioners and heat pumps offer additional features
that provide greater comfort (as well as additional energy
Two-speed units can run on low speed (using 50% of the energy)
up to 80% of the time, so they operate more quietly and run
for longer periods of time than single-speed models. Longer
operating periods translate into fewer on/off cycles, fewer
drafts and much smaller temperature swings -- only two or
three degrees instead of the four-degree swings common with
single-speed units. Plus, better air circulation helps prevent
air "stratification" warm air rising to the ceiling
and cold air settling on the floor. In short, you get consistent,
even cooling throughout your home.
Multi-Speed Indoor Unit
If you purchase a multi-speed or variable-capacity furnace
or fan coil with your unit, you will enhance both the comfort
and the efficiency of your air conditioning or heat pump system
Cooling efficiency for air conditioners and heat pumps is
indicated by a SEER (Seasonal Energy Efficiency Ratio) rating,
which tells you how efficiently the unit uses electricity.
Heat pumps also have heating efficiency ratings, indicated
as an HSPF (Heating Seasonal Performance Factor).
In general, the higher the SEER or HSPF rating, the less electricity
the unit will use to cool (or heat) your home. The government-mandated
minimum efficiency standards for units installed in new homes
at 10.0 SEER and 6.8 HSPF. Most air conditioners and heat
pumps manufactured before 1992 had SEER ratings below 7.0
and HSPF ratings below 5.0.
Air conditioners and heat pumps manufactured
today have SEER ratings that range from 10.0 to about 17.
Heat pumps are available with HSPF ratings from about 6.8
Usually, the higher the efficiency, the more expensive the
unit. But you will probably see the higher cost of a high-efficiency
air conditioner paid back (through lower utility bills) in
a few short years. Pro-Air can use cooling data from your
area to help you determine about how long it would take you
to recover the additional cost in energy savings. Of course,
after the payback, you continue to save on your energy bills
for the life of the system.
Tips On Matching Indoor & Outdoor Coils
Your central air conditioning or heat pump system is a split
system. That means it consists of two parts: an indoor unit
(coil) and outdoor (condensing) unit. Both components are
necessary for a working system. So if you install a new outdoor
unit, be sure to include a new, equally efficient "matched"
If you don’t replace both your indoor
and outdoor units, you won’t be getting what you paid
for. In fact, your system could be up to 15% less efficient
than stated — and you’ll be less comfortable,
too. That's why simply replacing just the outdoor unit isn't
a bargain in the long run.
Replacing the outdoor unit but leaving the
old indoor unit may offer you the lowest price, but it won’t
give you the best value. When your air conditioning or heat
pump components don’t match, you’ll be sacrificing
comfort. The system may still "work," but it won’t
perform up to the promised energy efficiency. Over time, this
will cost you more money. When the components aren’t
matched, it could create undue stress on your cooling system,
resulting in unnecessary, premature failure.