Cabinet Ventilation Fan Direction (Air in or out?)

[psumms]

Hi all, i'm looking to add a ventilation fan to tackle high humidity in the cabinet. About to install and just starting wondering, should the fan be extracting the hot humid air out of the cabinet or sucking cooler clean air in? I've Googled but found mixed opinions.

 

[dreamcatcherr9]

I’m curious what responses you’ll get. I’m guessing push hot air out? Fan inside, I’m debating similar (but with closed cabinet stand, I would need to create ventilation holes). Interesting question....

 

[Eagle_Steve]

I have a few of mine setup to push air out via a fan, but have a vent on the opposing side to allow drier air in. Works well for me like this.

 

[reeplay87]

Normally with ventillation you want both inflow and outflow. Pull cool air in and the cross breeze moves to push warm air out (you have to position your fans correctly). Same idea as a PC case.

 

[GlassMunky]

Ideally you’d have 2 fans of the same power: one pulling fresh air in and the other pushing hot air out

 

[Joenumba104]

For Ventilation it does not matter. The air exchange will happen. It only matters if you're attempting to cool something and you need to focus the air flow. I would suggest it be directed onto the waters surface if only to promote/focus air exchange in the water.

 

[psumms]

So... non-reef advice i've read elsewhere suggests the correct way to do this is drive clean air in to raise the air pressure inside the cabinet slightly higher that outside, this then forces the higher pressure out out of other openings... Otherwise, have similar balanced intake and exhaust fans working in tandem to maintain the same pressure.

 

[redfishbluefish]

Ideally you want fans blowing in. The reason is that blowing out exposes moist salt air to the fan, reducing its lifespan.

The other point is if you have multiple fans, all should blow in the same direction, blowing IN, with passive ways for the moist, hot air to escape. Let me explain....if I have one fan blowing IN at 400 gazintas, and one fan blowing OUT at 400 gazintas, the turnover in that canopy is 400 gazintas. Now, if I flip one of those fans to blowing IN, so two fans are now blowing IN, the turnover in the canopy would be 800 gazintas! Think about it.

 

[hart24601]

I personally would have the fan blowing in so it's not exposed to the humid air and potential salt spray as redfishbluefish said.

 

[krash7172]

Mine is blowing out so I can direct the hot, humid and maybe stinky air away like a bathroom fan.