Im looking for a fan to set up with my BrewPi, are there any recommendations?
I’m just using a decent 120mm PC fan which works fine
I like blowers better because you can wall mount them in your keezer more air transfer as well. Makes a big difference in first pour and keeping head down.
With the blower there is also the same problem as with the fans in this article, right?
I think the easiest way is the usage of PC fan with PWM (pulse-width modulation). These are fans who have four pins (12V, ground, speed signal, pwm).
I tested it with an old CPU fan (Arctic cooling Alpine GT64) and it seems to work fine.
For that I connected the 12V and ground pin with one of the RJ12 plugs and the PWM control pin to the 5V (+) of one of the outputs.
Edit: I also tried a Arctic Cooling F12 (http://www.arctic.ac/de_de/arctic-f12.html) without PWM and connected it directly to one of the digital outputs. It works well but only when the Brewpi is powered additional by the 12V power supply. When only connected to the RPi the fan runs but it didn’t start itself.
From a switching standpoint you are right. However a fan/blower to me has two functions. 1. To keep air as consistent throughout the keezer/fermentation chamber as possible. 2. Similar to the first point keeping draft lines for a keezer uniform in temp to the rest of the chamber for proper pours. Based on this logic a fan or blower to me is something that should just be plugged in and run constantly. I don’t see any added value in having the Pi control it.
I used a pc muffin fan in some 4" PVC
When hooking the fan directly up to the BrewPI am I going to need to get an external power supply? I have it powered with USB right now and when i plug the fan in and hear it groaning but not producing.
I did not try to control my fan and let it run 24/7 while fermenting because as soon as it stops you start getting stratified air layers in your fermenter (cold on bottom and warmer on top. I felt it was better to have better control over my temperature (typically 1/2 - 1 degree F) than worry about a four dollar fan.