Reset Windup:

The Proportional plus reset controllers act to eliminate the offset error found within proportional control through continuing to modify the output after the proportional action is finished and through returning the controlled variable to the setpoint.

An inherent drawback to proportional plus reset controllers is the possible adverse effects caused through large error signals. A large error could be caused through a large demand deviation or while initially be up the system. This is a problem since a large sustained error signal will eventually cause the controller to drive to its limit, and the result is known as "reset windup."

Since of reset windup, this control mode is not well-suited for processes which are often shut down and started up