Selecting a Temperature Controller on Amazon.com
A temperature controller is used to monitor and control heating and cooling in industrial processing, food processing, and commercial HVAC and refrigeration applications. It accepts input from an electronic temperature sensor and then adjusts a heater, air conditioner, or refrigeration unit to maintain the desired temperature. The controller prevents the temperature of the space or facility from falling below or rising above a predetermined point.
Three types of temperature controllers are on-off, proportional, and PID (proportional-integral-derivative). An on-off controller has a single set point that causes it to change state (turn on or off) only when the temperature reaches that point. A proportional controller also has a set point, but the controller manages temperature within a range around it, slowing the power of a heater when the temperature approaches the set point, for example. A PID temperature controller provides additional fine tuning of temperature control in response to fluctuations in temperature, and can automatically adjust to maintain steady control over the process environment.
Considerations when choosing a temperature controller include the type of input, the type of heating or cooling element to be controlled, and the features of the controller. A sensor such as a thermocouple or RTD (resistance temperature detector) sensor provides input to the controller. The controller sends signals to manage heating or cooling devices, and the types of devices vary depending on the application. Many controllers include the capability to accept more than one type of sensor, or set points that trigger an alarm if a constant temperature is exceeded, helping to prevent overheating in food and chemical processing. A temperature controller may have a dial on its face for selecting the temperature set point and displaying the process temperature. A digital temperature controller has a keypad for setting temperature and programming set points or alarms, and an LCD screen to display temperature, set points, and indicators. A controller may provide output to a computer for data storage, analysis, or monitoring. Manufacturers include Ranco and Omron.