do I buy a central air-conditioner, and what will it cost?
buy the complete system and servicing from an air-conditioning or heating
contractor like Bush.
prices vary from region to region, you should expect to pay at least $3,000
to $8,000 for a package that includes installation and hardware. The larger
the house, the higher the cost. Installation is cheapest and simplest if
the air-conditioner can be tied into existing heating duct, even if their
vents aren't optimally positioned to direct cool air into the rooms. But
if the contractor has to install ducts, the price will climb. The number
of ducts, their size and shape, and the amount of carpentry needed to hide
them in walls and ceiling will vary from house to house.
factors should I look for in a central air-conditioner?
factors that matter the most are energy efficiency and cooling capacity.
Of the two, efficiency is easier for you to determine. Manufacturers test
their central air-conditioners according to Government standards and give
them a Seasonal Energy Efficiency Rating (SEER), which lets you compare
competing brands for efficiency over an entire cooling season. For systems
of the same capacity, the higher the SEER the lower the operating cost.
This means an 12 SEER unit uses less electricity than a 10 SEER.
standards require any new central system whose compressor is separate from
its evaporator to have a SEER of at least 10. The most efficient new models
are rated at 18 or more, but some older model still on the market may have
a SEER of less than 10.
capacity is typically measured in "tons" of cooling, where one ton equals
12,000 Btu per hour. Other things being equal, the larger the capacity,
the more the equipment costs and the more expensive it will be to run.
A unit with too much cooling capacity for the house will cycle on and off
more frequently than a properly sized one, and it may not dehumidify the
rooms adequately. Researchers at Texas A&M University have found that
slightly undersized units are more efficient and better at moisture removal
than oversized systems.
even the most efficient air-conditioner, you can sharply reduce annual
operating costs simply by raising the thermostat setting two or three degrees-from
74 to 76 say. That kind of small temperature change shouldn't cause you
about dealing with humidity here in the South?
know how miserable humidity can make you. Well, with a variable speed air
handler you can reduce the humidity in your home, giving you and your family
a more comfortable environment.
fact, you'd probably be amazed to find out just how much moisture is in
your home. Consider this a humidity control system. This alone could take
out several more gallons of water a day.
can I find out how much cooling capacity I need?
use various rules of thumb, such as one ton of capacity for every 600 square
feet in a well-insulated house or one ton for every 500 square feet in
an under insulated house.
rough guides don't always make allowances for important variables-the amount
of sunlight striking a house, the area of exterior walls, the number of
windows facing east and west (those windows admit the most intense heat
in the summer), and so on.
sizing guides for contractors' use, such as one published by the Air-Conditioning
Contractors of America as "Manual J' (Load Calculation for Residential
Winter and Summer Air-Conditioning), allow for climate, house construction,
and other factors.
good contractor should take the time to calculate cooling capacity with
a guide like "Manual J" as part of the bid and to show you room-by-room
requirements for cooling load and airflow.
new air ducts have to be installed, how can I be sure the work is
good contractor will use a recognized set of duct-installation guidelines,
such as the Air-Conditioner Contractors' "Manual D." Ducts need to be designed
to deliver the proper amount of cool ;air to each room and to return a
comparable amount of air to the evaporator coil. If the system can't maintain
that balance, rooms won't cool properly and the air-conditioner may not
achieve its maximum efficiency. In extreme cases, the evaporator coil may
ice up, causing the cooling to stop and prompting a service call. The material
used for the ducts also matters.
duct, rather like an insulated version of the hose used for a clothes-dryer
exhaust, is the cheapest and easiest to install but also the most prone
to bending kinking, tearing, or leaking around joints.
board, a rigid fiberglass board with an outer barrier is cut and joined
with special tools and tape to make square or rectangular ducts. Duct board
is less susceptible to bending or kinking, but any tears in the outer barrier
or improperly taped seams can allow cool air to escape.
steel duct usually a combination of prefabricated and custom-made parts
for each installation, is generally the most expensive but also the strongest
and most durable. It needs to be insulated where it passes through uncooled
spaces-after all, you don't want to pay to air-condition the attic or an
matter what material is used, the sections of duct should be firmly connected,
not merely held together with duct tape. In order to maintain the proper
airflow, ducts should turn corners smoothly, not sharply, and be adequately
supported to prevent sagging. Cold air leaking from seams or migrating
through the duct walls can drastically increase overall operating costs.
the most watchful home-owner can't be sure the contractor has handled every
part of the installation properly. Your best protection against faulty
design or installation is monetary: Make the final payment to the contractor
only after the system is installed and you're sure it runs properly.
1750 Frankford Ave.
Panama City, Fl. 32405