Frequently Asked Questions - Air Conditioners
Here are some
simple guides for keeping cool without increasing your cost.
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Caulk, weather strip, and insulate the
attic to close air gaps.
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Plan your housework (washing and drying clothes, baking,
cooking) during cooler morning and evening hours.
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Close the drapes and shades over windows facing the sun.
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Keep windows and doors closed when the AC
is on.
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Use a thermostat control to automatically modify home temperatures for daytime/nighttime differences to save money.
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Set thermostat at highest comfortable level - remember, each degree raised reduces energy consumption by 3
to 4 percent.
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Replace your HVAC air filters every 6 months.
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Keep the outside unit free of leaves or other airflow
obstructions.
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Have the air conditioning unit cleaned and maintained each spring.
How does an
air conditioner work?
An air conditioner transfers heat from the inside of a
building, where it is not wanted, to the outside. Refrigerant in the system
absorbs the excess heat and is pumped through a closed system of piping to an
outside coil. A fan blows outside air over the hot coil, transferring heat from
the refrigerant to the outdoor air. Because
the heat is removed from the indoor air, the indoor area is cooled.
Is central air
conditioning better than window units?
This depends largely on individual circumstances for
example, how large is the area to be air conditioned, how large is the family,
what temperatures are required, how well the house is
insulated, where the house is located, etc. Central systems
require internal ducting; window units take up valuable window space. In many
cases, if more than three large rooms need air conditioning, it is best to
consider central air conditioning. Your contractor can advise you
Should I
augment my central air conditioning system with other air conditioners or
ceiling fans?
If you need to use other air conditioners with a central
air conditioning system, your central system probably is undersized or the air
distribution system is imbalanced. Window air conditioners or split ductless
systems may be used in rooms that lack air ducts.
Ceiling fans can be a good idea with some indoor
comfort systems because they circulate air that tends to stagnate at the top of
rooms with high ceilings.
What is the
average life of a central air conditioning system?
It can vary, depending on how much the system is used and
how regularly it is checked or serviced. Generally, the average life of cooling
units built in the 1970s and 1980s is about 15 years, but individual units may
vary and last much longer, depending on use and how well they are maintained.
Heat pumps have about the same life span, an ARI survey showed average heat
pump life to be about 14 years when recommended maintenance procedures were
followed. Newer units are expected to last even longer.
What should I do in
advance to make sure that my air conditioning system will work efficiently this
summer?
The main thing is to have the system checked each year
before the peak cooling season by a qualified contractor or service
technician. Then, remember to keep
the air filter clean and the outdoor unit free of leaves and debris.
If my air
conditioner is no longer cooling properly, what is the most likely problem?
It could be as simple as replacing a fuse, resetting a
circuit breaker or checking to see if the thermostat is set properly. If an
electrical problem isn't the cause, the refrigerant may be low
if the system still runs but does not cool properly. This
can be corrected by having an EPA certified technician add necessary
refrigerant. Most likely, if the problem involves any major part, such as the
compressor, you would hear strange noises similar to those of any mechanical
equipment not running correctly, or the unit might not run at all.
Can homeowners
repair their own air conditioners?
In most cases, definitely not. Cooling systems today are
more complicated to service and usually require expert attention in order to
comply with federal regulations, such as the Clean Air
Act which prohibits releasing refrigerants into the
atmosphere. An EPA certified air
conditioning contractor or service technician should be called at the first sign
of trouble.
When do I know it's
time to replace my system?
When the system starts giving you more problems than seem
cost effective to fix, particularly when major components such as the compressor
start making unusual noises or otherwise indicating need for a service call.
When faced with major repairs, consult several contractors for their
recommendations. Replacing a compressor is somewhat less expensive than
replacing the entire unit, but new units may give you greater efficiency and
lower operating costs in the long run.
Which is better
letting a central cooling system wear out before replacing it, or replacing it
at some point before it wears out?
Because newer equipment usually is more energy efficient
than older central air conditioning or heat pump systems, you might actually
save money by replacing your old system before it
completely wears out. Contact local contractors and ask for
their estimates. In some cases, the money you save in reduced utility costs
might pay back your purchase price of a new system years earlier than you might
think.
When is the
best time to buy an air conditioner?
Like most items, in the off season. That's when contractors
have more time to spend with you determining exactly the best options you would
want to consider for your individual needs.
How do I go
about shopping for a new system?
Ask friends and neighbors about the types of systems they
have, how much they cost, how long they've had them, and how satisfied they are
with them. Then ask for recommendations as to brands and local contractors, or
ask several different contractors to take a thorough look at your home, evaluate
your overall comfort needs, and recommend the best system for you. Look at all
indoor climate control options the entire spectrum of heating, cooling, air
filtration, and humidification equipment.
Should I
replace both my outdoor condensing unit (which includes the compressor) and the
indoor coil on my central air conditioning system at the same time?
In most instances, yes. Matching a new condensing unit with
a new coil is the only reliable way to be certain you are going to get the rated
efficiency of the new equipment. Matching a new, high SEER (seasonal energy
efficiency ratio) condensing unit with an old indoor coil probably would not
result in optimum efficiency.
What is the
best type of system to meet all indoor comfort needs?
The best system depends on many variables, including family
size, house location and design, and utility cost and availability. The optimum
indoor comfort system might include high efficiency central air conditioning and
heating, a high efficiency air cleaner, and a central humidifier.
If I buy a new
system, what is the best kind of control unit?
If you want flexibility to program your temperature
changes, a computerized thermostat will probably be best. Manually operated
control systems allow you to select a temperature setting which your unit will
maintain.
How can I get
a high efficiency system that will have minimum operational costs?
Manufacturers publish equipment efficiency ratings which
are available to your contractor. ARI also publishes directories indicating
various energy efficiency ratings of specific equipment.
It is important that a contractor install a unit that has
just the right capacity to cool your home. Units with excess capacity will cycle
on and off and work less efficiently, thus increasing your operating costs.
How can a homeowner
tell if a contractor's price is fair?
Mostly by comparing bids from several contractors, and
possibly checking the local Better Business Bureau to be sure the contractor has
a good reputation.
How easy is it to
install central air conditioning in an older home?
Often it is fairly simple, particularly if the older home
has existing duct work or plenty of room for adding duct work.
Homes without air conditioning ducts can consider non ducted systems
which also provide the advantage of cooling only selected areas very
effectively. An important consideration is how well the older home is sealed and
insulated.
If I'm buying a
house, how can I make sure that the air conditioning system is in good working
order?
Just turn on the system and listen for unusual sounds while
feeling how cool the air is and how strong the air flow is from the vents.
Don't just listen inside the house go outside and listen to the
condensing unit, too. This personal inspection is a good indicator, but like
buying a car,
the best way is to then hire an expert a contractor to
come out and inspect the system. It won't cost much, and it could save you lots
of money in unanticipated repairs.
What is a heat pump?
A heat pump is like a conventional air conditioner except
it also can provide heat in winter. In the summer, the heat pump collects heat
from the house and expels it outside. In the winter, the heat pump extracts heat
from outside air and circulates it inside the house. The heat pump works best
when the outdoor temperature is above freezing. Below that, supplementary heat
often is needed. A heat pump can save 30 to 60 percent less energy to supply the
same heat when compared to an electric furnace with a resistance heating
element.
Are air conditioners
and heat pumps efficiency rated?
Yes. Central systems are rated by the seasonal energy
efficiency ratio (SEER). Many older systems now in use have SEERs of 6 or below.
By 1994, the average SEER for all units shipped by
manufacturers in the U.S. improved to 10.61 for central air conditioners and
10.94 for central heat pumps. The higher the rating, the more efficient the
system.
What are the
advantages of buying a system with a high SEER (seasonal energy efficiency
ratio)?
You will use less energy to cool your house, resulting in
lower electric bills. Sometimes the savings are enough to partially or fully
offset the cost of the new equipment within a few years. In all cases, it's an
individual calculation which the homeowner should figure out with the contractor
of choice.
Is there any
law or rule covering air conditioning efficiency ratings?
Yes. The National Appliance Energy Conservation Act of 1987
(Public Law 100-12) sets national standards for residential air cooled central
air conditioners and air source central heat pumps.
The NAECA provides for a federal minimum standard of
10.0 seasonal energy efficiency ratio (SEER) for split system air conditioners
and heat pumps, effective Jan. 1, 1992, and 9.7 SEER for single package air
conditioners and heat pumps, effective Jan. 1, 1993.
Heat pumps also are subject to federal standards of
6.8 heating seasonal performance factor (HSPF) for split systems, effective Jan.
1, 1992, and 6.6 HSPF for single packages, effective Jan. 1, 1993.
What is the
difference between a split system and a single package central air conditioner
or heat pump?
A split system has one of its heat exchangers (which
includes the compressor) located outdoors and the other (the indoor coil)
located indoors. A single package has both heat exchangers located in the same
unit, usually indoors. Most residential central air conditioners and heat pumps
are split systems.
How can I determine
the SEER of my present equipment?
There are three main ways to determine the SEER of
equipment: (1) find the model numbers of your present equipment (the outdoor
condenser/compressor unit and the indoor evaporator coil unit) and check them
with local contractors who handle your brand; (2) estimate the SEER based on the
average SEER units produced approximately when your system was installed; or (3)
check the energy efficiency label on your outdoor condenser/compressor unit if
you have equipment produced after late 1988.
In the first method, contractors can then consult
manufacturer data or the ARI unitary equipment certification directory which
lists all models of equipment by manufacturers that certify their equipment SEER
ratings. In the second method, for air conditioners and heat pumps
produced in 1981, the first year SEER criteria was used, the average ratings
were 7.78 and 7.51 respectively. By 1987, SEERs reached 8.97 and 8.93
respectively.
By 1994, ratings increased to 10.61 for air conditioners
and 10.94 for heat pumps. In the third method, residential central air
conditioners and heat pumps covered under Department of Energy (DOE) test
procedures and manufactured on and after June 7, 1988, are required to have
labels containing energy efficiency information.
For each system, the label will be on the outdoor condenser/compressor
unit, and will reflect the SEER achieved by matching the outdoor unit and the
indoor evaporator coil unit.
How can I find the
savings of higher SEER equipment compared to lower SEER equipment?
You'll need to talk with a local contractor to verify what
size cooling equipment you now have and what you actually need, then determine
the normal cooling load hours for your area, and find your electric rate cost.
When cooling, heat pump performance is measured in seasonal energy efficiency
ratio (SEER). When heating, it is measured in coefficient of performance (COP)
or heating seasonal performance factor (HSPF). In all measurements, the higher
the rating the more efficient the system.
The formula is as follows:
Capacity (Btuh) Cooling
Load Hours
--------------- X ------------------
X Electric Rate = Annual Operating Cost
SEER
1000
For example, if a home requires a unit with a
capacity of 36,000 British thermal units per hour (Btuh), is located where the
cooling load is 1500 hours and the electric rate is 8 cents per kilowatt hour,
here is the calculation for a system with a SEER of 10:
36,000
x 1500
------
X ---- X .08 = $432 per year
10 1000
The same calculation with a SEER of 12 reveals an annual
operating cost of $360 or $72 less per season 17 percent savings.
What are typical
savings to expect from higher SEERs in various parts of the country?
Here are representative operational costs of three SEER
levels for a 2,000 square foot split level house in six regions of the United
States (actual costs may vary greatly depending on individual circumstances):
REGION
SEER 7 SEER 9
SEER 11
Southeast
$757 589
482
Southwest
469 365
298
South Central
964 749
613
Northeast
301 234
192
Northwest
100 77
63
North Central
364 282
231
What percentage of
my utility bill is caused by air conditioning?
It can be surprisingly small on an annual basis, but it
depends on how much you use your air conditioning, how efficient your equipment
is, and how much you conserve energy by actions ranging from insulating your
home to keeping doors and windows closed when the system in operating. You local
electric company is the best source for specifics in your area.
Is there any
difference in the quality and quantity of cooling and heating from a heat pump
and that from other cooling and heating systems?
No. In its cooling mode, a heat pump supplies exactly the
same kind of cooling as all electric air conditioners. In its heating mode, the
temperature of the air supplied by a heat pump is not as hot as the air supplied
by a fossil fuel furnace, but the end result is the same:
a warm, comfortable home. Air temperature from a heat pump at room
outlets normally is about 100 degrees Fahrenheit compared to about 120 to 130
degrees from a fossil fuel furnace.
The heat pump warming effect thus is something like warming
your bath water more gradually and uniformly by turning the hot water faucet to
a moderately warm setting rather than turning the faucet all the way to maximum
hot water.
Do all heat pumps
come with supplemental heat?
Virtually all heat pumps are available with supplemental
electrical heat. Some heat pumps are used in conjunction with a, fossil fuel
heating system such as gas or oil. Whether supplemental heating is necessary
depends on your climate and home location. Your local contractors can advise you
as to whether supplemental heat is necessary, and what type of heat pump might
be best for your needs.
Should I install a
heat pump instead of a regular air conditioner if I have a gas or oil heating
system?
A heat pump can be a worthwhile consideration no matter
what heating system is used in a home. In many areas, a heat pump with gas or
oil supplementary heat is the most economical system and offers excellent
performance and comfort.
However, check with local contractors who can determine the
best systems for use in your area that meet your comfort needs.
How often should I
change the air filter in my system?
Check it at least every month during peak use, and replace
it when it looks dirty enough to significantly impair the air flow through it.
Some filters, such as media filters or electronic air cleaners, are
washable; others are disposable and must be replaced.
Will I get cleaner
air by shutting up my house and running my central air conditioner or heating
system, or by opening up my house as much as possible to let in fresh air?
As you might suspect, this depends primarily on the quality
of air outside your home, the quality of air inside your home, and your home's
indoor comfort equipment. Indoor air quality varies greatly from building to
building. Factors may include everything from emissions by the materials used in
your home's construction to the kind of cleaning products you use for personal
and household needs, to possibly even radon from the ground or water in some
areas.
Optimum air quality is a matter of personal
preference, as is deciding when it is best to air out the home, and when it is
best to rely primarily on the cooling/heating equipment. Research on indoor air
quality is gaining momentum, but it may be years before comprehensive analysis
of the spectrum of variables affecting indoor air quality is widely available to
households nationwide.
Using a high efficiency air cleaner on the central
cooling/heating system remains one of the best ways to help maintain a clean
indoor environment. High efficiency air cleaners can remove particles smaller
than the eye can see.
How, and how often,
should I clean my air conditioning registers and ducts?
Duct outlets and registers should be cleaned as part of
your regular home cleaning routine. It's the filters in the system and to a
lesser degree the grilles and registers at the duct outlets that collect most of
the dust, and therefore need changing or cleaning.
Ducts usually don't require cleaning, especially if filters
are kept clean. You can occasionally check ducts by removing a few registers and
inspecting the ducts from the inside with a flashlight (be sure to look at
return air ducts). If the insides of ducts need cleaning, some contractors
provide this service.
Should my home be
humidified?
That depends largely on your climate and personal needs.
Humidification is definitely helpful in many homes and businesses.
Particularly during cold weather, insufficient moisture in the air often
is responsible for such assorted problems as stuffy noses, sore throats, even
more dust than usual, cracks and dried out joints in wood furniture, wilted
plants, and static electricity which jolts hair, clothes, and computer disks.
Indoor relative humidity may fall to around 7 percent, much drier than even the
25 percent relative humidity of the Sahara Desert! Ideal indoor relative
humidity is between 30 to 50 percent.
Is there any
advantage to letting the air conditioner or heat pump fan run all the time (the
"on" setting on the thermostat) instead of periodically (the
"auto" or "automatic" setting on the thermostat)?
If you live in a very humid climate you may not want to run
the fan continuously because this reduces dehumidification, Other wise, there
are some potential advantages.
Continuously circulating the air keeps the temperature more
even throughout the house by alleviating temperature stratification. It keeps
air circulating through the comfort system's air filter, which depending on
filter type and efficiency can keep the home cleaner and the air fresher to
breathe. When the fan is operating continuously, the compressor continues to
periodically cycle on and off automatically to cool and dehumidify your home
just as it does on the "auto" setting.
How do I know my
equipment is ARI certified?
Equipment certified by manufacturers to ARI as being
accurately rated is subject to ARI verification testing. This equipment normally
is identified by an ARI certification seal on the outdoor unit of the equipment
or on its operating instructions. If no seal is evident, ask your contractor or
contact ARI. Ask your contractor to show you the appropriate ARI product
certification directory that lists the units you are considering. Then have your
contractor go over the various ratings with you.
Can my cooling or
heating system reduce or eliminate radon or other "sick building"
problems?
As a gas emanation primarily from soil or rocks, radon can
be detected and measured by relatively inexpensive monitors that are becoming
increasingly available to the general public. Considerable research is being
done on measures to control radon and its health effects as typically found in
indoor building environments residential and commercial. At present, most
conventional home central cooling and heating systems appear to have little, if
any, effect on radon.
"Sick building" essentially refers to some
buildings which have excessive concentrations of pollutants. Such pollutants may
range from cigarette smoke to chemical emanations from materials used in
furniture or building construction, to biological contaminants such as fungi
(e.g., molds and mildew) and bacteria growing in areas where moisture may
collect and stagnate. This may occur in such diverse locations as improperly
maintained or damaged ceiling tiles, dishwashers, carpeting and air conditioning
drain pans.
Most problems allegedly have occurred in commercial
buildings. Cleanliness and adequate
ventilation are major considerations. If you believe you may have a problem, you
should seek the advice of a qualified contractor.
For more information about radon and sick building
problems, contact your local American Lung Association state radiation
protection office, or Environmental Protection Agency regional office.
Is there any
relationship between my home air conditioning system and chlorofluorocarbon
(CFC) refrigerants and the ozone layer?
An international protocol limits future worldwide
production and consumption of the fully halogenated CFCs 11, 12,113,114, and
115.
Virtually all of the refrigerant used in residential
central air conditioning systems is called HCFC-22, which has some
ozone depletion potential, but only one twentieth that of CFCs. This is because
HCFC-22 breaks down fairly rapidly when released into the lower atmosphere, and
most of it never reaches the ozone layer at high altitudes.
HCFC-22 will be phased out of production for use in new
equipment by the year 2010 and for servicing existing equipment in 2020.
After its phase out, there will still be some of this refrigerant
available for servicing existing equipment. Manufacturers are beginning to
produce units that use alternative refrigerants.
Consumers can thus enjoy their air conditioning and help protect the
environment at the same time by following a few simple guidelines:
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A central air conditioner is a closed system and will
not release refrigerant into the atmosphere as long as it is maintained
properly. Have your system checked by a service person once a year before
the cooling season. Make sure the technician checks for refrigerant leaks.
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After July 1, 1992, intentional venting of refrigerant
is against the law. All refrigerant from units must be recovered.
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Only patronize service companies that practice
refrigerant recovery and recycling and have the proper equipment to do so.
Is there anything
dangerous about the refrigerant in my central air conditioning or heat pump
system?
The refrigerant (HCFC-22) in residential central air
conditioning and heat pump systems is nontoxic, nonflammable, odorless, and
sealed within the system. Nonetheless, like any substance, it can be abused. You
should be aware that some people have died from deliberately inhaling or
"sniffing" pure gas (e.g., after buying and "sniffing" cans
of refrigerant like those used to recharge automobile air conditioners).
Inhaling such concentrated refrigerant vapor can cause cardiac irregularities
and cardiac arrest—a fatal heart attack.
Although a large release of refrigerant vapor could
displace oxygen available for breathing and cause suffocation, this is virtually
impossible with residential systems because of the relatively small amount of
refrigerant used in the 24,000 to 36,000 Btuh (2 ton to 3 ton) units of most
residential central air conditioning systems.
In hot weather,
should I turn my thermostat up when I leave for work in the morning?
If your house is going to be empty for more than about four
hours, it's a good idea to turn your thermostat up to about 82 degrees or so
instead of the 78 usually recommended. Keep the house closed to minimize heat
build up. When you come home, don't set the thermostat any lower than the
temperature you actually want your air conditioning system wouldn't cool any
faster and might easily waste money by cooling your home more than needed.
For Additional Information on Portable Air Conditioners:
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