Frequently Asked Questions of your 

Heating and Air Conditioning Specialist

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.

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.

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.

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.

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.

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.

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.

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.

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.

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-
esidential 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 occur-red 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 phaseout, 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:

* 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.

* After July 1, 1992, intentional venting of refrigerant is
against the law. All refrigerant from units must be recovered.

* 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

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