January 28, 2018 written by Kurt Shafer
The history behind the Tornado line of gravity and hybrid rooftop ventilators starts in 2008 when I became aware of the residential whole house fan business. I began selling whole house fans on EBay and was mildly successful. By 2012 I had created a better design that started selling. I found out that Australia had just two sources for whole house fans so I posted a web site, Invisco.com.au, to serve that market. In 2015 I got my first order there and I started looking for  parts made in Australia to fill my order.
I found a source, CSR Edmonds, near Sydney, and asked them for a quote for ducting. The export sales manager, Allan Ramsay, called to ask what I was doing. When he learned how much I knew about ventilation and the US market he decided to assign me to be his distributor to the US. We met in Long Beach at a ventilation trade show and signed a contract. I created EdmondsUSA and opened a web site, http://www.EdmondsUSA.com.
The Edmonds  line consists of two types of ventilators, the Hurricane gravity ventilator  and EcoPower motorized ventilator. The heart of their line is their unique rain hat. Unlike any American rooftop, the Australians crafted a perfect turbine with vertical blades.
The beauty of this simple design is that it offers the best possible free air flow up and out while offering impeccable rain resistance. A search for “edmonds hurricane ventilator finds many images like the one above. 
Edmonds makes the Hurricane gravity ventilators in sizes from 100 mm (4 inches throat) up to 900 mm (36 inches) in 100 mm increments. These high performance ventilators are used all over the world. An excellent example is India, where SUDHA VENTILATING SYSTEM PVT. LTD. http://www.svswindventilators.com/ offers a full line of the Hurricanes. 
In 2016 I realized that the Hurricane rooftop design could be an excellent addition to my whole house fan product line and enable me to offer the best rooftop whole house fan in the US. I contacted Allan Ramsay to ask if I could license the design for use in the US. He replied that the product was not patented so I was free to make it here. He asked only that I not call it a Hurricane. Hence the source for my name, Tornado. 
Edmonds sold the Hurricane for years and then realized that they could improve it by adding a motor so that it could pull even more air. They created their EcoPower line of hybrid rooftop ventilators that was recognized by AMCA in 2016 with the creation of an entirely new class, “Hybrid Rooftop Ventilators”. The EP900 is their flagship – 36 inch throat and 5,885 CFM under power. 
Edmonds made the decision to motorize the turbine. They felt that inserting a blade in the air flow would reduce the free air gravity flow. The result is that the turbine is excellent when there is no static pressure but the flow falls off fast with any pressure. Specifically, the air flow at 0.1 SP is just 2500 CFM and at 0.2 it is zero. 
The Edmonds hybrid EP series is being sold in India by the same company, SUDHA VENTILATING SYSTEM, on their other web site, http://svspoweredventilators.com/
Since I had the goal of creating the best rooftop whole house fan using my motor and blade, I took the opposite path. I built a 20 inch throat model and put it on my 20 inch attic mounted whole house fanI found that the air flow up and out of the turbine rain hat was better than I expected. I got 8000 CFM through it at full RPM. And because it has a powerful blade, it pulls over 7000 CFM at 0.1 SP. Below is a picture of the blades – 8 of them with 50 degree bites.

The range of products that are possible with my patent is large. The applications include all gravity ventilation needs up to 36 inch throats and beyond. The applications for motorized ventilators cover the same market. 
Here is a graphic comparison showing the Invisco ventilators outperforming the Greenheck and LorenCook products.

Here are some of the other Greenheck models that can be replaced by the new Tornado gravity and hybrid rooftops. In the case of the powered models, only those with performance up to about 15,000 CFM can be replaced.
Gravity models  GRS/GRSF,  FGI/FGR ,  RGU
Powered models  RDU/RBU/RBUMO ,  TAUB-CA,   AX , TAUD

There are many case studies that prove the value of this design. 
The University of Washington in Seattle and the Park at Pearl Ridge are two great examples. It is important to note that both designs were forced to derate the Edmonds EP900s because of ambient static pressure. The Seattle design dropped the usable CFM from 5,885 to 2,500 per ventilator. That tradeoff would not have been necessary with this new Tornado design. 


Below is proof of the value of these hybrid rooftops. This is a picture of a design done by a well known Southern California engineer James Shwe of MarokoShwe.com. You will see that there are multiple hybrid rooftops in the design. Mr. Shwe now uses hybrid rooftops in place of gravity or motorized rooftops in all his new designs. If you would like to talk to him about this, email me – kurt@invisco.com

The result of all this work is that I have a patent pending that contains not only the hybrid design but also the turbine rain hat. I am looking for a US company that serves the rooftop ventilation market to buy or license this design.
Thank you for your interest in my new Tornado!
Kurt Shafer
Cell 951 296 3611

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