CPU Cooling Fan Placement Questions

[maporsche]

I have a large canopy (18in tall) and I need some advice on where to place my CPU fans (92mm, 4 total). I have no problem wiring these up to be place anywhere in the tank/sump but I need to know where the most effective places would be to keep the water cool.

The canopy is open back.

Should I place these on the back of the canopy (suspended from the top about half way down) blowing air in? Blowing air out?

Should I place these under the tank stand in a similar fashion?

Should I have these blowing on the water? If so, in what positions in the tank (the middle, the edges, center?)

Should I have these mounted near the front of the canopy blowing air back to the rear, open end?



I'm curious what each of you have done with your setups and what is the most effective. My temp is at 84 deg near the end of the MH lighting period and I need to get it cooler before summer.

 

[fishrfreinds]

blowing in is better.
get 4 place 2 on top 2 on the bottom to keep the air cool. Keep the air between the tank and light the coolest thats were all the heat goes in the water. have them close to back to get the cool air in,

 

[melosu58]

I dont have a conopy on this tank but on my last tank I had mine on side blowing out. You want the fans IMO to blow the heat out so it wont heat up your tank.

 

[MadManMac]

There is sometimes a potential problem with all the fans blowing either in or out. It can iether create pressure inside, albeit very slight, or the reverse, an ultra slight vacuum. Wither way the fans have difficulty moving air. If the canopy has an open back then this is not really a problem, but either way, I like 1 or 2 blowing across the water and the other two at the top blowing out the hottest of the air.

 

[ellisz]

I have 2 80mm fans on the roof of the canopy blowing out and a 120mm fan on the back blowing in

 

[melosu58]

Almost like a cycle

 

[fishrfreinds]

But he has a open back
Blowing out is point less cause your not really get in the fresh in. if he had a close canopy then yes blowing out is better. Holes on one side then fan on the other.

 

[maporsche]

But he has a open back
Blowing out is point less cause your not really get in the fresh in. if he had a close canopy then yes blowing out is better. Holes on one side then fan on the other.

Yes, I have an open back. I will have all 4 fans blowing in. 1 at each corner of the tank blowing towards the middle. I'll let you know how much my temp drops. It's roughly at 84deg at the end of my 6 hour MH cycle.

 

[fishrfreinds]

Brovo Chap.

I know my CPU fans. i have them with my pc lights. The air in the canopy will be a lot cooler. Before I installed Cpu fans, ever time i open the canopy lid there would get this breeze of really hot air. and would need to live the lid open . but now the fixture stays cool and the canopy outside dosent get hot.

 

[fishrfreinds]

oh and quick note if your diy this make sure that power supply is DC 12 not DAC 12. I didnt notice that until it was to late fry'd my first batch of fans.

 

[MadManMac]

Actually, if it is an open back canopy blowing out will be better than blowing in. When blowing out, there is not any hot air recirculting inside the canopy it is all drawn out and the equal volume of cool outside air gets pulled into the canopy throuhg the open back. So really, blowing in causes more of the heat to stay within the canopy rather than blowing out of it. Either way, the extra air movement will help keep the temperature lower.

 

[maporsche]

I'll try to test it both ways to hopefully end the dispute (at least the dispute over my open back design). I'll start this weekend and let you guys know.

 

[fishrfreinds]

trust me if its open bac, blowing in is better. Suc in air when you hand is about 4" from your mouth. Doesnt feel that much cooler. then blow lightly, it cools off a lot better. same thing with youre canopy. so yah thats your choice. hope it informed you.

 

[MadManMac]

The other side of it is to create a tunnel with you hand and blow into it, it actually gets hotter. When you inhale through the same tunnel it cools the air much more. One thing to remember, even with an open back, if there is a wall, it will not flow completely out of the tank and will circulate. That is why I also originally said that you should have one point in and three point out, it guarantees good air flow across the water while removing all of the heat as well.

 

[Brenden]

Suc in air when you hand is about 4" from your mouth. Doesnt feel that much cooler. then blow lightly, it cools off a lot better.

That is simply because you are directing the are towards your hand. Air movement is directed to a specific spot.
You need to force air into the canopy from the front somewhere. If it is from top of canopy sides etc is up to you. Having fans on the back assisting in removing air will also help but pushing the air into the canopy from somewhere other than the open back will move more air volume.

 

[fishrfreinds]

the air that your blowing is warmed by body. Now if you place the tube the 4" away its cool. But thats the beside the point its that he has a open back meaning you cant really get a strong suction. If it was closed then blow out is way better.

 

[melosu58]

Trust me is the wrong thing to say. Try saying in the future, IMO. THats all it really is. Just because you say, dont make it the absolute truth. Other people have ideas and esp experiences that overule your trust me.

 

[maporsche]

Trust me is the wrong thing to say. Try saying in the future, IMO. THats all it really is. Just because you say, dont make it the absolute truth. Other people have ideas and esp experiences that overule your trust me.

Well, my first test is with the two top fans blowing out, and the two bottom fans blowing in. As I've stated, my temp has been hitting 84 degrees at the end of the lighting period. I'll tell you guys tomorrow what it reaches. The fans will come on 30 minutes before the lights and stay on for 1 hour after the lights.

 

[melosu58]

Good that you keep an open mind. Many ways to do something. Let us know the results

 

[Brenden]

Just for info purposes. I have one 12" fan that runs 24/7 and a second that turns on/off with the lights.