Fermentation Chamber Fan wiring

In other posts on fans and wiring its been mentioned that a 12V PWM case fan with a 12v AC to DC power supply can be used effectively to move air inside the fermentation chamber.

If I’d like to have the fan turn on during heating and cooling how would i wire this? In the above quote I’m not exactly sure what the wiring suggestion means. Can anyone elaborate please? Would I need a 3rd SSR for the fan or can I somehow utilize the two existing SSRs?

As others suggested, I would get a simple fan with speed control, like Antec Tricool.
You can keep it running permanently on low, and set it to high during a cold crash.

Thanks Elco. I’ll look into that.

I’m still wondering how a fan like that would be wired into the brewpi? My Brewpi is hooked up through usb to my raspberry and doesn’t have its own power supply. I’ve included my wiring diagram below with a third SSR for the fan and 12v DC/AC Adaptor. This seems not quite right though, as I’d really like to figure out a way to integrate this fan simply without a third SSR, ideally having it switch on anytime EITHER the heat tube or the compressor of the fridge is switched.

It is now recommended to run the fan continuously on low power, the Antec tricool fans for example have a switch to toggle the speed.

When you are cooling, the back of the fridge will drop in temperature. After the cooling, you also want to move the air around to distribute that to other parts of the fridge.

If you want to control the fan with an SSR, you would do that on the AC side. Your schematic looks correct for that. An alternative would be to buy a PWM fan (4 pins) with a transistor inside that can be switched with 5V directly.

If I get this right, the PWM fans does not require external 12V source (ie, PC ATX PSU) and can be driven by BrewPi Spark by itself? Can someone please point out how to wire it on output of Spark and RJ12 input? Thanks in advance.

No, a PWM fan has a 4th pin that allows you to turn in on and off with a 5V signal. The transistor is inside the fan, so you do not need to add one externally. It still needs 12V.

Got it :wink: Thanks! Is there any small 12V psu recommendation, to avoid using full sized ATX psu?

So no point in PWM fan if I want it to be running all the time?

I got this 12v power supply which is quite small from Mean Well (RS-15-12):


Hey Elco - still using my BrewPi (non-spark) and loving the beers and control. Just ordered a TriCool Fan like you mentioned but wondering if there’s another post depicting the wiring of such a fan into the system… (I’m novice at wiring - got through the initial BrewPi build by the skin of my teeth)

Couple of questions about hooking a 4 wire PWM fan up to the spark:

  1. Do we hook the sense wire up to anything on the spark? My assumption right now is that we leave that wire alone
  2. Each 5v output is two pins. Which one goes to the control wire? Basically, what’s the pinout of the 5v digital outputs? Is it 5vdc, gnd, 5vdc, gnd, etc?
  3. Can the spark set the fan speed?

Hi MtnSoul, I’m interested in adding a fan to my build. Did you succeed at adding the TriCool fan? Can you share your experience?

does this mean that a 5 v PMW fan described still needs a 12 v power supply?