Selecting a central air conditioner is an important decision, since the air conditioning system is a home's largest energy user.
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The right AC system makes a home comfortable and efficient. The wrong one can cause discomfort, humidity and maintenance problems and increase your utility bills.
Purchasing an AC unit is one of the largest investments- both at purchase and in operating costs homeowners can make in their property. As with any major purchase, the more information you have the better decisions you can make.
When searching for a conscientious, licensed, bonded contractor, contact your regulatory agency to make sure the contractor you select has a satisfactory rating. The regional office should be listed in the business white pages in your local telephone directory. The contractor you select should complete a cooling load analysis, and a humidity load analysis. In addition, the contractor should provide service after the installation and an AC operation manual.
A cooling load analysis calculates how much heat enters your home in one hour when the outdoor temperature reaches 95 degrees. This analysis ensures that even at 95 degrees your AC capacity will be sufficient to remove the unwanted heat. An incomplete cooling load analysis can cause you to make a poor AC choice.
Many contractors simply estimate the cooling load and the size of equipment you need based only on the square footage of the home. Often this rule-of-thumb approach used one TON of air-conditioning per 500 square feet of floor area. This estimate usually results in improper equipment size. A reputable contractor will complete a load calculation that also includes a humidity load. If you are replacing a unit, a load analysis should be done by a HVAC contractor to determine if the older unit Size is really appropriate.
Heat passes through the walls, roof, windows, and doors and is generated by people in the home. The load calculation should consider all of the following heat and humidity factors:
Many other factors can increase a home's humidity. Cooking, extra people in the house, lighting, and moisture from the bath, house plants, kitchen or laundry contribute to indoor moisture and increase the home's cooling load.
Air conditioning equipment is available in many different sizes for different types of homes. The term "size" refers to the combined cooling capacity and dehumidification capacity. A cooling load analysis gives the required size of the AC unit based on the largest expected heat gain of the house. Cooling load and equipment size is expressed by BTUH (British Thermal Units per Hour) or TONS; one TON of AC equals 12,000 BTUH. Many contractors simply add 25 to 30 percent to the cooling load analysis to account for humidity. In many homes this shortcut can actuallyincrease humidity levels reaching 30 to 50 percent of the total cooling analysis. In humid areas, it is important to have a cooling load analysis that gives the humidity gain including moisture from outdoor air, cooking, showers and washing
Once the cooling load analysis is completed, the heat and moisture gain should be compared to the heat and humidity removal capacities of other models on the market. Different models and brands of AC equipment, rated at the same overall capacity, can have varying moisture removal capacities. So check both heat and moisture removal and compare to your contractor's calculations.
Purchasing an AC unit is one of the largest investments homeowners can make in their property.
Contact your local Regulatory Agency to help you make a decision on an HVAC contractor.
Air conditioning equipment is available in many different sizes for different types of homes.
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