High Efficiency Air Conditioning

When purchasing new air conditioning equipment, be sure to check the efficiency rating of the proposed unit. A higher-efficiency rating will result in lower operating costs. Cooling energy efficiency is designated by the term "SEER" (Seasonal Energy Efficiency Ratio) for residential central air conditioning systems (5 tons or less). Window air conditioners are rated using "ERR" (Energy Efficient Ratio), as their use is typically intermittent. Both of these terms are a measure of the unit's output or cooling capacity divided by the power input at standard conditions. New units have EER's/SEER's ranging from 8.5 to 17.0.

For split systems with an outdoor unit and an indoor coil, the efficiency varies with the match between the indoor cooling coil and outdoor condensing unit. The manufacturer should be consulted to determine the combined efficiency. The American Refrigeration Institute (ARI) publishes an annual directory listing various combinations of outdoor units and indoor coils with their SEER or EER rating. Most major manufacturers' product lines are included in this directory.

Besides a unit's EER or SEER, there are additional energy-saving features to look for when selecting an air conditioner for your home.

• Consider adding to, or upgrading the unit controls with a setback thermostat or a tamperproof thermostat for homes with small children.
• Look for high efficiency fan or blower motors and scroll compressors.
• Consider a waste heat recovery system (or desuperheater) to provide domestic hot water if the home has a large demand for hot water coincident with substantial space cooling requirements.
• Variable speed drives for fans
• The unit should meet CSA standard C273.3.

System Sizing

Correct unit capacity is critical to optimum efficiency. Both over and under sizing lead to poor operating efficiency. The size of the unit is a function of the compressor, the main energy-consuming component. The larger the compressor the more energy will be required to operate the system. An oversized unit will cycle (turn on and off) more frequently. An undersized unit will operate longer and may not have the capacity to adequately cool the house to the desired temperature. When it is time to replace your current air conditioning system, have the air conditioning and heating contractor perform a load calculation using industry recognized methods, to determine the proper size unit.

Installation and Maintenance Guidelines

General maintenance of your air conditioning equipment is simple and will keep the unit working at optimal performance. The following are some guidelines that should be followed.

• Keep the manufacturer's instructions, control drawings, design documents, and any other relevant information for future reference.
• Maintain adequate space around the outdoor unit to avoid airflow restriction through the coils.
• Locate the outdoor condensing unit where it will be shaded from the summer sun.
• Locate filters and controls where they can be replaced or maintained with minimum aggravation.
• Replace filters regularly. Vacuum dirt and dust from the indoor coil once a year to prevent restricted airflow.
• Keep the out door condensing unit clear of leaves and debris.