Below is a comparison of rooftops made by 4 sources, Greenheck, Loren Cook, Edmonds Australia and Invisco Industrial ( the Thorwaldson Tornado). This comparison is based on a 20 inch diameter throat. You can see the leader is the Tornado. For larger buildings Invisco Industrial makes larger fans. An example is the Tornado 48 inch fan. It pulls 20,000 CFM at 975 watts and offers gravity air flow estimated to be over 4000 CFM in a light 7 MPH breeze. . The illustration below is meant to show the value of the new AMCA classification – “Hybrid Rooftop Ventilator”. You can see that the other American made sources have restrictive rain hats. Edmonds and the Tornado use a modern turbine rain hat that allows very good gravity ventilation for free along with motorized air flow when needed. You will also note that the turbine offers air flow when powered at far less electric power than the other US sources.
Write Tornado@InviscoIndustrial.com with your building parameters for a free quotation.