Rafter Mounted

Rafter Mounted Systems

These are the quietest systems you can find. Not only are the fans quiet all by themselves, but when you hang them from your rafters high above your insulated ceilings and close the attic access hatch, you barely hear them and you don’t see them. There are several manufacturers of these systems. Here are some highlights:


It is June 2016 and here is the latest. Airscape offers their 5.0e that is rated at 5064 CFM and pulls 810 watts. Since QuietCool and Invisco both pull more air at less power I have a difficult time understanding why Airscape would be a choice.

In April, 2014, Airscape  changed their 2 top systems, the 3.5 and 4.4, to make them both 7 speed units. Then, 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 3.5 and 4.4 from operating without adequate window openings. Airscape is now also offering a temperature sensing and recording package.

In 2012 Airscape  introduced new web based remote controls for their  3500 and 4400 CFM machines. These controls are usable with laptops, desktops, tablets and smart phones. Airscape also 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 5 speeds on the 3500 and 6 speeds on the 4400.Models are 1000, 1532, 1700, 2800, 3500 and 4400 CFM


Updated Nov 15 2016 – To add Invisco’s ES6320 – 6,320 CFM at 500 watts.

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 3981 CFM and takes 640 watts to do that. QuietCool offers you 4435 CFM at 494 watts.


Update Nov 15 2016. Invisco announces 6,320 CFM in their 20 inch model ES6320.

In an attempt to make this site a diary of events and improvements, I am adding new info as it occurs.


The latest news as of Feb 2015 is that Invisco has landed their first order in Australia. The customer is a licensed contractor in Brisbane area and has offered to be Invisco’s dealer and installer there. Invisco now offers more performance points than any other Australian supplier.

In 2013 Invisco announced the world’s first fully automatic temperature sensing “SmartSpeed(tm)” that knows how hot your home is. This enables the  Invisco whole house fans with the infinitely variable speed motors to start up on high speed when your home interior temperature  is 85 degrees or more. Then as the temperature in your home drops under 85 the SmartSpeed automatically lowers the speed and the power consumption drops automatically until, at 60 to 75 degrees (depending on your setting), the fan turns off automatically. There is a manual override if you want to set the speed yourself.

Because the Invisco SmartSpeed automates the power use, these are the most power efficient systems you can find.

Invisco systems all work with the X10 and Insteon PC and smart phone remote control but the infinite speed control and automatic operation make remote control unnecessary.

Invisco is the only company to offer rafter mounted CFM levels higher than 4700 from one motor and fan blade. The larger systems pull so much air volume that they must be connected to more than one ceiling opening. The 8400 CFM system must have 2 20 inch ducts and the larger units are shipped with 3 or 4  20 inch ducts. CFM performance range is 1220 up to over 25,000.

Invisco is the only company to offer a 3/4 HP option to increase air flow at each blade size from 24 inches up.

Invisco also offers the Patent Pending R60  insulated dampers.


QuietCool has 4 product lines with 5 performance levels in each. They range from 1500 CFM to 6500.  The largest systems use 2 fans and motors. The ES is their “EnergySaver” line that uses the new ECM brushless DC motors.

Tamarack Technologies

Tamarack has 2 rafter mounted products, the  1100 and 2200 CFM “Infinity” models.

I need to mention R.E. Williams (1850 CFM with (4) 8 inch inputs from 4 ducts) These 8 inch ducts are not competitive with the systems shown above.

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