Vent fan output louvre


There is also a louvre on the inside of the grow chamber, placed on the VENT FAN (motherboardassemblyguide.pdf). I have assembled the vent fan now but it seems hardly powerful enough to open up the louvres…
It is not exactly the same one as on the BOM but it has about 70% of its air displacement capacity (126m3/hr or 74CFM). It is a so called PWM fan which apparently can increase or decrease the speed of the fan. I have no PWM signal (or do I ?) so I just connected 12V and GND. Is it now running on maximum capacity ? In NOT, will the arduino provide a signal that makes it speed up ?
If NOT… the louvres will have to go, otherwise hardly any air is being let through.
Any suggestions ?


I suppose that if you are using your fan connected directly to a 12V power supply you are using 100% duty ratio, which would be maximum capacity.
The louvre I have is very light, and if you blow air through it, it easily opens. I think 74 CFM would be enough for that.
It is good to use it so that you limit the air exchanges inside the box (better control), and also prevent insects from coming in. But it’s not extremely necessary.