Instruction Manual - CVF49This manual will show you how to install, use and maintain the CVF4 Ventilation Unit. The CVF4 is meant for ventilating solarradiation sensors with the purpose to keep the mounted radiometer window or dome clean from dew, precipitation andpollution. It can be used outdoors under all-weather conditions. The CVF4 has a built in heater to keep the air just aboveambient temperature.Both the World Meteorological Organisation (WMO) and the Baseline Surface Radiation Network (BSRN) guidelines advise usinga ventilator to optimise the performance of radiometers in general.The use of the CVF4 will:- Increases the maintenance interval.- Increase the accuracy of the measured data (cleaner dome / window)- Reduce the zero offset of the radiometer.The CVF4 is meant for all CM, CMP, SMP, CG, CGR and CUV radiometers. However with the CMP 3 and SMP3 and CGR 3 theventilation effect will be less due to the larger opening around the dome. The CVF4 is meant to run continuously. The heater caneither be switched on permanently for cold regions or be switched by a data logger or clock to remove dew in the morning andbe switched off afterwards. In that case the heater is operated from a 2 hours before sunrise to an hour after sunrise. This savespower in situations where power is limited such as PV operated sites.This manual, together with the instruction sheet, give information related to installation, maintenance, product specificationsand trouble shooting of the CVF4.If any questions should remain, please feel free to contact your Kipp & Zonen dealer or e-mail: info@kippzonen.com .For information about other Kipp & Zonen products or to check for any update of this manual, go to www.kippzonen.com .1. Introduction