The answer to 'water heater short cycling' is that the water heater is turning on and off frequently, which can be caused by several common issues. Short cycling can lead to higher energy bills and potential damage to the water heater over time. Some of the most common causes include a faulty thermostat, sediment buildup in the tank, or a problem with the heating element.
If you notice your water heater short cycling, it's important to address the issue promptly. Depending on the cause, you may be able to fix the problem yourself, but in some cases, it's best to call a professional HVAC technician to diagnose and repair the issue.