Hello, I have a few attic vents that look like the Jupiter 2 style attic fans. I actually thought they were fans until I went up into the attic. Has anyone retrofitted the vents with actual attic fans. Preferably without having to remove the vent and disturbing the roof. Maybe tap off the light for electric. Anyone have any advice or ideas. Thanks in advance.

[villagetinker]

If I were going to do this, I would measure the opening of the existing vent, then go to Lowes, ACE, or Home Depot (or online) for a Gable fan of around the same size, large enough so the screw mounting holes will be outside the existing hole. These typically mount with 4 screws one in each corner. The sheathing is typically 5/8 so 5/8 inch screws would not penetrate the shingles or under layment. I would also install a thermostat to control the fans.

[elevatorman]

If you are going to do this make sure you have enough air coming in through your soffits. If you don't you will be drawing air from the vent right next to the fan. So how do you do that you ask? Well you go outside look at your soffit and count the little holes around your house measure the size of the holes add them all together and there you have it. Or you could find out who manufactured the soffit and they will list the Net Free Area ( NFA) in square inches. Multiply that by the linear feet of your soffit. Whatever that works out to be the number should be larger than the openings in your roof. In other words intake should be larger than the exhaust. Building codes have requirements for this. This video shows how different soffits restrict airflow. https://www.youtube.com/watch?v=svfWcm126wE

Exactly what I was thinking. Didn't think of screwing it in like that. I wonder if the vibration would cause it to come loose over time. Could probably run some 2x4's with all the trusses up there. Thanks.