GRAVITY ROOFTOP VENTILATORS WERE FIRST
Greenheck and LorenCook and Twin City and PennBarry and many others make them. Most have rain hats that force the air to go down before it can go up. In May 2005 CSR Edmonds in Seven Hills, New South Wales, Australia introduced the most effective gravity ventilator – their Hurricane – effective because it uses vertical turbine blades under a rain hat to offer air nearly unobstructed flow up and out.
MOTORIZED ROOFTOP VENTILATORS CAME LATER
When the flow of air needs to be faster than free air flow then motors are used in different mechanical designs. They power various methods of moving air – propeller blades are the most common. Most American made systems use a lot of horsepower to overcome the restriction of air flow caused by the rain hats.
HYBRID ROOFTOP VENTILATORS ANNOUNCED IN 2008
Edmonds engineers realized they could add a motor to the very effective gravity ventilator to make it move more air when powered. They decided to motorize the turbine. This resulted in their EcoPower line in 3 sizes, 400 mm throat (16 inch diameter) , 600 mm and 900 mm throat. The decision to turn the turbine resulted in good air flow and performance when there is no static pressure but very poor performance in static pressure.
In 2015 Kurt Shafer was assigned by Allan Ramsay, Export Sales Manager at Edmonds, to become the United States distributor for Edmonds Hurricane and Edmonds EcoPower rooftop ventilators. Kurt created EdmondsUSA and opened a web site,
IMPROVED HYBRID ROOFTOP VENTILATORS
In 2016 Kurt founded http://www.InviscoIndustrial.com and invented an improved hybrid rooftop ventilator, the Tornado. You can see the comparison between 4 rooftop ventilators – both gravity and motorized – below.