Ultra Quiet WC & Utility Room Extractor Silent Fan. The Silent 125 is designed to solve ventilation problems in small rooms such as a utility room. The extractor fans are fitted with a pilot light, backdraught shutter and airflow guide vanes as standard. Fitted with motors mounted on silent elastic blocks, the fans deliver incredibly quiet running and exceptional performance with stylish features, making it a high performance yet silent fan. This is the larger model for use with 125mm / 5 inch diameter ducting. Adjustable Timer: After disconnection, the shut off time can be delayed between 1 and 30 minutes. Adjustable Humidity Sensor: The level of humidity for the bathroom can be chosen from between 60% and 90% RH. The Silent 125 extractor fan will continue to work long enough to reach the selected level.