The right choice, placement, and installation of sensors are critical to a control system’s optimal operation. The most common reason why control systems don’t work well enough is because of defective sensors. This article outlines the primary sensor types and selection criteria that are most commonly utilized in HVAC control systems by band heater provider.
Kinds of sensors
Temperature, humidity, carbon dioxide, and other variables that have a big influence on occupant comfort may all be measured with sensors that can be fitted.
HVAC Temperature Gauge
Temperature sensors are the most widely useful form of sensor. They are useful in even the smallest and most basic HVAC systems. Temperature sensors are essentially just mechanical switches that can trigger by a material’s thermal expansion or contraction. As an alternative, a temperature sensor might trigger by changes in the electrical resistance of certain materials brought on by temperature fluctuations. Or by variations in the pressure of a particular liquid or gas.
Humidity Measurements
Measurements of humidity may also be very important for an HVAC system to run efficiently. Relative or absolute humidity can be sensed using humidity sensors, which then use a transmitter to transform the observed values into an output signal of 0-10V, 0-20mA, or 0-100% PWM. The two most widely used types in automated control systems are the cooled mirror type for applications requiring higher precision and the capacitive film sensor for the majority of applications.
HVAC Pressure Gauges
Measurements of pressure, either as a difference in pressure between two places in the system or as a value relative to the atmospheric pressure (gauge pressure), can be useful in the design and operation of an HVAC system. A diaphragm that moves with increased pressure is typically visible in pressure sensors. Measuring the diaphragm’s displacement yields the pressure value. Several often-used applications include air filter condition monitoring, air volume damper adjustment, and duct air flow monitoring.
Sensors for Air Quality
Sensors measuring air quality are useful to track whether certain air pollutants are within allowable bounds. They are frequently useful in demand-controlled ventilation systems, where the amount of carbon dioxide in the air, for instance, serves as a signal that humans are present in the space. Additionally, sensors for total volatile organic compounds (VOCs) are available to track the concentration of harmful particles.
Selection Criteria
When choosing RTD sensor supplier and installing a sensor for a particular application, you must take several factors into account. First and foremost, it is important to confirm that the chosen sensor can detect the quantity being studied (such as temperature, humidity, CO2, etc.), that the sensor’s detecting range includes the expected range of values, and that the sensor has the appropriate accuracy and sensitivity.
Furthermore, in some particular applications, the sensor’s reaction time—that is, the amount of time it takes for the sensor to change its output signal in response to a change in the measured quantity—may be very important. The sensor’s time constant, which shows the necessary amount of time, is the crucial factor in this case.