From Consumers reports 2006:
What’s the best way to ensure that the central air-conditioning system you choose is
installed properly, and will provide the most efficient and reliable cooling for your home?
The pointers below can help you to find the right hardware and the right technician to
install your system, whether you’re replacing an older air conditioner or installing one for
the first time. The information comes from our experts.
And while there’s no one money-saving strategy that will work for everyone all the time,
there are simple steps that you can take, as we show in keeping costs down. In some
cases, you may be able to cut back on air-conditioner use considerably without
seriously inconveniencing your family.
In a “split system,” the typical design, refrigerant circulates between an indoor coil and a
matching outdoor condenser with compressor. The refrigerant cools the air,
dehumidifying it in the process; a blower circulates air through ducts throughout the
house. A variation is the “heat pump,” a type of system that functions as heater and
cooler. When used as an air conditioner, a heat pump discharges heat from the house
either into the air or deep into the ground. In the winter, a heat pump extracts heat from
the ground or the air to warm the house.
This describes how much cooling the unit delivers for each watt of electricity. Efficiency
is expressed as the Seasonal Energy Efficiency Rating, or SEER. At present, a SEER of
10 denotes a low-efficiency unit; medium efficiency is 11 to 14; high efficiency is above
14. New federal regulations that took effect in 2006 set the minimum SEER for a central
air conditioner at 13.
A synonym for the air conditioner’s cooling capacity, size is measured in British thermal
units per hour (Btu/hr.) or in “tons.” One ton of cooling equals 12,000 Btu/hr.
Get the right contractor
Finding a trustworthy contractor to install and service an air-conditioning system matters
the most. Here’s how to choose:
Seek referrals from neighbors, family, or business associates. It’s wise to get price
quotes from at least three contractors.
Check the background
Contractors who bid on your installation should show you proof of bonding and
insurance, plus any required contractor’s licenses. Check with your local Better
Business Bureau and consumer affairs office for complaint records. It’s a plus if
technicians are certified by a trade organization, such as North American Technician
Excellence or HVAC Excellence, to service residential heating and cooling equipment.
These and other similar programs assess the technician’s knowledge of specific types
of equipment and its proper service methods. We believe that a contractor who has
made the effort to get certified and has practiced this trade and learned from several
years of service and installation experience, will be a better service provider.
Contractors who bid on your job should calculate required cooling capacity by using a
recognized method like the Air Conditioning Contractors of America’s Residential Load
Calculation Manual, also called Manual J. An additional reference for assessing
ductwork needs is Manual D. The calculations produce a detailed room-by-room
analysis of cooling needs. Ask for a printout of all calculations and assumptions,
including ductwork design. Be leery of a contractor who bases estimates merely on
house size or vague rules of thumb.
A service plan that combines regular inspections with discounts on repairs and a labor
warranty is worth negotiating into the overall price. Prices for such service vary widely.
At a minimum, regular inspections should include these steps:
- Check for and repair refrigerant leaks.
- Detect and correct duct leaks.
- Inspect and tighten the electrical connections, checking for damage.
- Clean the coils, drain pan, and drainage system.
- Vacuum the blower compartment.
- Replace filter monthly or as recommended by the manufacturer.
Choose the right unit
If you’re replacing an old central-air system, you can expect to pay around $3,000 for
the equipment. If you need ductwork installed because you’re starting completely from
scratch or are upgrading a forced-air heating system, expect to pay $6,000 or more.
Improving the system’s air-filtration capabilities is also easiest to do as part of a general
Brand plays some role in the selection.
Here are other factors that may affect reliability:
- Matching new equipment with old. If you replace only the condenser, you have a “field-matched” system that can be less efficient than advertised and that may require more repairs because of undetected incompatibilities between the two.
- Damper-zoned cooling. A large or multistory house is often divided into several heating and cooling zones to improve temperature control. However, this type of system is complex and has many more moving parts and controls and so may require more repairs.