92 mm fan mount for supply air valve by Anot

Last crawled date: 3 years, 3 months ago

This design is very specifiic but I hope it can be of use or inspiration to someobody.
My bedroom has an air valve but no windows. The ventilation in my building is on the lower side making the intake from this valve irregular at best. To improve ventilation I therefore made this simple insert that fits a 92 mm computer fan (with slighty cut corners) in the ventilation hole which is 128 mm in diameter. Based on fan diameter a 120 mm fan would be able to fit but because of the square-shaped mount design of the fan this is not possible without removing the frame. Even a 92 mm fan is a tight fit, and requires the corners for the screw holes to be cut slightly (about 5 mm from each corner). I found this could be done with a regular pair of scissors with some force after softening the corners with heat from a lighter. This is also why the fan insert corners have been "cut". The place for the 92 mm fan is designed with some tolerance and should need fastening, I therefore added screw holes so that you could fasten a bracket behind the fan (or rather in front if you plan on using it as intake as I am). However, I found the fan could easily be attached by wedging the fan wire and therefore never came around to designing a bracket.
Unless you plan on running the fan only on low speeds you'd probably want an air valve that can be opened wide as the air pressure (at least on my fan) is to low too effectively make the air pass when the path is obstructed.
How you want to power the fan is up to you, but as an example I connected the fan to a 12 VDC psu from an old TV-box in line with two switches. One to turn it off and on, and one to switch between full speed (12 v) and lower speed (6-7 v using a resistor). Basically only things i had laying around.
Dimensions:
Insert
Length: 7.5 cm (with fan)
The shape of the insert is irregular, but encompasses a cylinder of 120.5 mm in diameter. (might work to fit a 120 mm hole with some slight filing of the corners)
"Baseplate"
L W H : 106.5 mm 106.5 mm 3.5 mm, The base was made to snap onto my valve plate and would probably need rework for other variants.