Here are the highest performance attic mounted and rooftop whole house fan sources arranged in order of top performance measured by calculating the CFM per watt of power. Here are the results:
Thorwaldson ES-6400 – 6320 CFM 505 watts = 12.5 CFM/W
QuietCool STL PRO-7.0X 6996 CFM 725 watts = 9.6 CFM/W
Thorwaldson Whole House Fan Company now has the highest performance attic mounted system, the ES-6400, that pulls a record 6,320 CFM in a 20 inch diameter body. And the only rooftop mounted whole house fan, the ER-8000 that pulls 8005 CFM through a 20 inch diameter vertical shell with the best rain hat in the world, the InviscoIndustrial Tornado. The fan body includes a damper to prevent air falling in the winter.
The ER-8000 rooftop whole house fan is perfect for homes with no attics like those on mid century modern homes ,mobile homes and the adobe houses in New Mexico. Thorwaldson systems all work with the X10 and Insteon PC and smart phone remote control for AC power. Both systems are the lowest power systems in history with just 505 watts at highest speed. The USMotors EC Motor (ECM) has infinitely variable speeds. The ES-6400 comes with a full 16 year warranty.
In 2018 QuietCool announced many new model numbers and new specifications. They also announced their 7000 series fans based on a 24 inch blade. The performance they offer is still under that of Thorwaldson – based on CFM per watt. The STL PRO-7.0X is rated 6996 CFM at 725 watts or 9.65 CFM/Watt.
QuietCool has 4 product lines with 5 performance levels in each. They range from 1500 CFM to 6,123. The largest systems use 2 fans and motors. The ES is their “EnergySaver” line that uses the new ECM brushless DC motors.
Airscape offers their 5300 that is rated at 5350 CFM and pulls 825 watts. It has more speeds than any other system on the market except Thorwaldson (Airscape offers 10 speeds, Thorwaldson offers infinite speeds). Since QuietCool and Invisco both pull more air at less power and lower prices it is hard to understand why Airscape would be a choice.
In 2017 Airscape announced new model numbers and their new 10 speed control.
In 2016, apparently due to problems with remote control users turning their fans on without having windows open, Airscape came out with a pressure sensing system to inhibit their fans from operating without adequate window openings. Airscape is now also offering a temperature sensing and recording package.
In 2012 Airscape added ECM motors to those models to achieve better efficiency. But instead of taking advantage of the infinite speed control available from the ECM motors Airscape chose to provide a fixed number of speeds.
This company offers German fans that they would hope you favor over American fans. But the performance is not there. Their most powerful fan , the 4.0, is rated at 4028 CFM and takes 640 watts to do that.
Tamarack has 2 rafter mounted models, the 1100 CFM and 2200 models.
All the rest are mounted on the ceiling.
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Kurt Shafer YOUR Whole House Fan Guy 951 296 3611
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