In a closed-loop HVAC control, what happens when the sensor detects deviation from the setpoint?

In a closed-loop HVAC control, what happens when the sensor detects deviation from the setpoint?

• A. The system immediately shuts down to protect equipment.
• B. The setpoint automatically changes to match current conditions.
• C. The controller adjusts the actuator to reduce deviation toward the setpoint.
• D. The sensor recalibrates without changing outputs.

Answer: (C)

In a closed-loop HVAC control, maintaining the target condition relies on feedback. The sensor watches the actual condition and compares it to the setpoint, producing an error signal that represents how far off you are. The controller uses that error to decide how much to move the actuator. By adjusting the actuator—the damper, valve, fan speed, etc.—the system pushes the process variable back toward the setpoint. This corrective action happens continuously, so the temperature or other climate variable settles near the desired value. Shutting down the system would be an extreme protective action, not a normal response to small deviations. Automatically changing the setpoint would defeat the purpose of maintaining a consistent condition. Recalibration of the sensor is a maintenance task, not an immediate response to deviation in normal operation.

In a closed-loop HVAC control, maintaining the target condition relies on feedback. The sensor watches the actual condition and compares it to the setpoint, producing an error signal that represents how far off you are. The controller uses that error to decide how much to move the actuator. By adjusting the actuator—the damper, valve, fan speed, etc.—the system pushes the process variable back toward the setpoint. This corrective action happens continuously, so the temperature or other climate variable settles near the desired value.

Shutting down the system would be an extreme protective action, not a normal response to small deviations. Automatically changing the setpoint would defeat the purpose of maintaining a consistent condition. Recalibration of the sensor is a maintenance task, not an immediate response to deviation in normal operation.