- 1). Find a contractor accredited by the Air Conditioning Contractors of America (ACCA). Do research so you can ask intelligent questions. Refer to ACCA Manual J, "Residential Load Calculation." Ask for an Air Conditioning, Heating and Refrigeration Institute (AHRI) certificate to document proper matching of the outdoor air conditioning unit and the heating unit.
- 2). Be certain that existing ductwork can handle the new unit, especially when adding air conditioning to an older home. ACCA Manual D provides guidelines for residential duct design. Ask the contractor to check for damaged or leaking ductwork as part of the installation, and consider insulating it.
- 3). Make sure the contractor does proper calculations and does not just install a unit like the old one. The federal Energy Savers website points out that many older homes have oversized units. (See References 1) Get more than one bid before making a purchase, and choose the contractor who follows the ACCA guidelines and who will provide calculations to support the choice for unit size.
- 4). Become familiar with effiency standards like the Seasonal Energy Efficiency Ratio (SEER) and Sensible Heat Ratio (SHR) rates, as these are efficiency standards. As explained on the University of Florida website: "SEER ... indicates the unit's efficiency in removing heat per kilowatt of power used. National standards now mandate a minimum SEER 13 for all units manufactured after January 2006. The higher the SEER, the more efficient the unit. SHR ... indicates the portion of the cooling load that reduces indoor temperatures. The remaining portion goes towards removing moisture. Units should have a SHR of approximately .7. This means that 70% of the energy used by the unit goes toward cooling and 30% goes towards removing moisture."
- 5). Contact your local utility to request additional information for sizing the heating and cooling units. Some utility companies do these calculations for free. Also ask about any rebates for energy-efficient units. Seek this information from the contractor, too, as government rebates (local, state, and federal) are often available.
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