Normal Air Conditioner Cycle Times

Providing the Groundwork for AC Normal Cycle Times

The Air Conditioning Contractors of America (ACCA) has developed specific guidelines for proper airflow distribution design and correct AC equipment and size selection to reach cooling load requirements. Manual D of the ACCA, for example, sets proper air speed at the return grille of the AC system below 500 feet per minute and a maximum supply air speed at the register under 700 feet per minute. This should provide for long and efficient AC on cycles of 9 minutes or more and prevent humidity from creeping into your indoor air.

A proper AC unit running under a normal cycle time in your home should help keep your energy bill low, keep indoor moisture out and create a comfortable and quiet flow of air throughout the house. Airflow inside your home should move at a relatively low speed, allowing the filters in your AC system to do their job and prevent the system from placing undue stress on your AC unit. Furthermore, normal cycle times will keep AC system maintenance low.

For an air conditioner unit to provide a correct cycle time, it has to match the cooling load needs of your home. You need to take into account the normal temperature for your geographical area and the ideal indoor temperature as well. For this, contractors use Manual J and other reference material developed by the ACCA to calculate the cooling needs of your home and recommend the appropriate AC unit size.

Perhaps the most prevalent cycle time problem is due to an oversized AC unit. This is not the only one or the most damaging one, though. According to John Proctor in “Home Energy: Sizing Air Conditioners,” a larger than normal home with restrictions in the duct system and inadequate ceiling insulation lead to electric utility peaks and high-energy costs. So proper inspection and an adequate maintenance schedule for your heating, ventilating, and air conditioning (HVAC) system will help you reach and maintain normal air conditioner cycle times.