This Wisconsin company has expanded its line of propeller upblast roof exhaust fans with additional sizes and expanded performance. The units are designed to discharge contaminants up and away from buildings. Three performance levels are available, based on horsepower capacity. The addition of a Size 20 in a belt drive model allows for proper operation of a fan's butterfly dampers at reduced air volumes.

Greenheck, P.O. Box 410, Schofield, WI 54476-0410; 715/359-6171; fax 715/355-2399; on the Internet: