ABSTRACT
The definition of reset control is “automatically adjusting a setpoint as a function of some changing condition.” Its most common application is with hot water systems. A reset controller is a controller that can perform this function. Instead of one sensor, the controller has two sensors associated with it. Reset control can be limited outside the range of the reset schedule. Reset control is also commonly used in discharge air applications, where the air handling system tries to maintain a constant “cool” discharge air temperature setpoint, for use by zoned VAV terminal units and/or reheat coils. The dehumidistat overrides the air handler into a cooling mode upon a rise in space humidity level above setpoint.
