Conrad Electronic WS222 Notice D'emploi page 73

c) Cleaning the Multipurpose Sensor and the Outdoor Sensors
After a longer period of operation in the open, dust can deposit at the plastic surface of the outdoor
sensors. It can be removed rapidly with a cloth slightly moistened in water.
Never use a garden hose to clean the outdoor sensors, because they are only protected
against rain coming from the sky above but not against jets of water coming from the sides
or below.
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