Wetterdamper

Wetterdamper (also called weather damper in English) is a device used in heating, ventilation, and air conditioning (HVAC) systems to moderate the influence of outdoor weather on indoor humidity and moisture levels. It is typically installed as a damper in the intake duct of an air handling unit to limit moisture ingress from outside air.

The wetterdamper operates by modulating outdoor air flow based on humidity, dew point, or weather data, often under the control of a building management system. When outdoor humidity is high or the dew point nears indoor conditions, the damper can restrict intake or close during rain or snow events to reduce moisture load. It may work in conjunction with economizers, balancing ventilation requirements with humidity control.

Construction usually involves a blade-type damper housed in a weather-resistant frame, with materials chosen for corrosion resistance and long service life. Seals help minimize air leakage, and some designs include weatherproof actuators or integrated rain protection. The device is commonly paired with upstream filtration and downstream humidity control equipment such as dehumidifiers or humidifiers as part of a complete air handling strategy.

Applications are common in commercial buildings, data centers, hospitals, and industrial facilities where precise humidity control is important or outdoor weather can cause large moisture fluctuations. Benefits include improved indoor humidity stability, reduced risk of condensation and mold, and potential energy savings by avoiding excessive ventilation during humid conditions. Proper sizing, control strategy, commissioning, and maintenance are essential to prevent inadequate ventilation or humidity buildup. See also economizers, humidity control, and ventilation management.