Presents the results of a laboratory evaluation of humidity sensors for use in HVAC systems. Sensors to measure the humidity of the air entering and leaving cooling coils are required in the determination of coil loads and supply air quality. Three different humidity sensors were tested, one that measures the dewpoint, and two that measure relative humidity. States the dewpoint sensor showed a 1.6% overall average percent error from the standard for both the cooling coil inlet and fan outlet calculated absolute humidity in an environmental chamber. The standard deviation of the sensor was 0.75% for fan outlet measurements. After selecting the dewpoint sensor as the most accurate, the sensor was evaluated for its response time in an operating fan/cooling coil setup. States the results showed the response time as acceptable for both inlet and outlet conditions.

KEYWORDS: Humidity, measuring, instruments, testing, sensors, heating, ventilation, air conditioning, laboratory testing, cooler batteries, relative humidity, dew point, accuracy, comparing