Setting HVAC cycles accurately helps ensure that your A/C or furnace provides maximum efficiency, lowest costs and optimum cooling or heating performance. "Cycling" simply refers to how many times the unit turns on and off every hour. The duration of on and off cycles is an important metric to evaluate how efficiently an HVAC system is operating. Here are some reasons why:
Consequences of cycles that are either too short or overly long include excessive wear and tear on critical components such as the air compressor or furnace heat exchanger.
Poor performance is another common result: The indoor environment and overall comfort may be impacted by a variety of symptoms, including erratic temperature swings, excess indoor humidity, and overly hot or cold rooms.
Noisy system operation as the unit cycles on and off frequently — or, conversely, runs almost constantly — is also annoying.
Excess energy consumption and higher operating costs are another factor.
Generally speaking, a central A/C or furnace should cycle on for about 15 to 20 minutes before cycling off again. In other words, about three to four cycles per hour. Both short-cycling and overly long cycles can be indications that something is amiss. Here are some examples of potential issues related to setting HVAC cycles:
Short-cycling may indicate that the BTU capacity of the air conditioner or furnace is too large for the size of your home. The unit produces too much cooling or heating when it cycles on. Therefore, it shuts off too rapidly. This can degrade indoor comfort and also put excessive wear and tear on critical system components, leading to premature failure.
Long cycles can result from problems such as insufficient airflow—most commonly caused by a clogged air filter or ductwork issues such as excessive leakage. Also, if the unit is undersized, i.e., the BTU capacity of the furnace or air conditioner is too small for the size of the house, it may run almost nonstop to achieve the thermostat setting. Another common cause of long-cycling specific to air conditioners is a refrigerant leak.
For qualified professional service to diagnose issues relating to setting HVAC cycles, contact Air Assurance.