Each exhaust fan is chosen specifically for the installation. The fan is large enough to ventilate exhaust gases along with ambient air. The induction of ambient air and the larger hoses used on the Nederman system allow the fan to last longer then sealed systems because the motor and bearings are kept below 160 degrees. Ducting for Nederman systems is spiral G-90 galvanized pipe with a minimum wall thickness of 24 gage. Joints may be sealed with high-temperature silicone. Because the system is designed for negative pressure, brazing and welding is not required.