Common equipment in HVAC systems includes air conditioning units, which function to remove hot air from indoors using a water system, achieving ideal indoor temperature and humidity. During this process, several sensors are utilized, such as: water temperature sensors, air differential pressure switches, duct temperature sensors, duct temperature and humidity sensors, CO sensors, and CO2 sensors.
The image above is a schematic diagram of an air conditioning unit. The air conditioning unit consists of a fresh air section, supply air section, return air section, and exhaust air section. There is a filter in the fresh air section leading to the supply air section, along with a hot and cold water control valve and a fan. Typically, an air differential pressure switch is installed on the filter to detect whether it is clogged, and a freeze protection switch is installed on the hot and cold water pipes to ensure water supply. At the outlet of the supply air section, a duct temperature and humidity sensor and duct pressure sensor are installed to monitor the temperature, humidity, and airflow of the supplied air. In the return air and exhaust air sections, there are fans and filters. Generally, a duct temperature and humidity sensor is installed at the return air inlet to monitor the temperature and humidity at the inlet, and an air differential pressure switch is installed on the filter to detect whether it is clogged. These are the commonly used sensors in air conditioning units. The above are personal opinions and are for reference only.