The answer to 'why is my water heater short cycling' is that the water heater is turning on and off repeatedly, which can be caused by a few common issues. Short cycling can be due to a faulty thermostat, a problem with the heating element, or sediment buildup in the tank. This rapid on-off cycling wastes energy and can shorten the lifespan of the water heater.
If the water heater is short cycling, you'll notice the tank is not heating up all the way before the burner or heating element shuts off. The tank may never reach the set temperature before it cycles again. This can be frustrating and lead to inconsistent hot water. Addressing the root cause is important to fix the short cycling issue.