Short cycling occurs when a mechanical system that operates in cycles turns on and off more frequently than expected. Short cycling can occur in air compressors, furnaces, chillers, AC units, fans, and pumps. This rapid state-change adds unnecessary stress on the equipment, reducing its lifespan and efficiency.
You can learn more about short cycling in our article on motor current signature analysis.
Verdigris provides an automatic alert that notifies you if we've detected symptoms of short cycling.
If you receive a short cycling alert, review the following checklist to help identify some of the most common causes.
For cooling and refrigeration systems:
- Is the air filter dirty or blocked? This can impede the system's airflow and cause it to overheat.
- Are refrigerant levels low? This can cause the system to overheat and shut down.
- Are the evaporator coils frozen? This can prevent the system from removing heat effectively and cause a malfunction.
- Was the thermostat recently reprogrammed? Was this implemented correctly?
- Was the system appropriately sized for the space being cooled? If the system is oversized, it will overcool the space and cause large temperature swings and stress on the system.
For air compressors, motors, and similar machinery:
- Are there any leaks? Follow manufacturer guidelines to check for leaks, which will cause a malfunction of the machinery.
- Is the condenser dirty, or is there other material buildup? This can cause a system malfunction.
- Is the motor overloaded? This can overheat the system and cause a shutdown.
- Is there a sufficient operation time delay? A time delay that is too short can cause the system to run even if there is discharged air still circulating in the system immediately after its operation.
- Is the pressure/temperature control differential sufficient? If not, the system can take longer to achieve a setpoint and cause short cycling.
For water pumps:
- Has the water tank lost its air charge? Is there more water in the tank than there should be? This could indicate a natural loss of air in older bladderless tanks, or damage or failure of the air bladder.
- Is there any visible damage to the pump pressure control switch? Is the switch sensor opening clear or clogged with debris? This can affect the controls from functioning properly and may result in short-cycling or complete failure.
- Is the water supply piping or water filter clogged? This can increase pressure in the system, causing the switch to cycle.
- Is the air pressure in the water tank overcharged? This usually corrects itself but could cause short-cycling under certain conditions.
- Is there a water leak anywhere in the system? If there is a leak in the tank (air or water) or any piping then you may find the pump cycling excessively even when no water is being used.
- Is the tank too far from the pressure control switch? This can cause short-cycling at certain times during a cycle.
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