Question - Cooling Fans

D.G. · #1 03/17/2007, 11:12 AM

This is a topic that I have seen some discussion on in the past. I remember there are those of you that have your own reasons on how you place cooling fans in the canopy. I am running two cooling fans in the rear under my MH and have them pulling into the canopy. Just wondering what direction everyone is running their fans. I have heard some talk about salt seepage if you direct the fans in one particular direction. Don't mean to get this into a big hairy discussion but just wondering what is the most effective way to run these fans.
Thanks,

cisco680 · #2 03/17/2007, 11:35 AM

Not sure about the salt creep but it will be more effective cooling if you pull in at one side and exit at the other end. Similar to computers by having fans that draw in and a exit fan will increase the amount of cool air running through the case. Try it both ways and see which one works better.

dugg · #3 03/17/2007, 10:29 PM

I have 1 in 1 out. The one blowing out gets eaten up with salt and rust about every 2 years.

TheMcs · #4 03/18/2007, 07:48 AM

Ditto, 1 in 1 out.

eddybabyhd · #5 03/18/2007, 08:06 AM

both out for me

djc1026 · #6 03/18/2007, 08:22 AM

1 in, 1 out for me.

Dave

jjmcat · #7 03/18/2007, 11:35 AM

I have both blowing in.

D.G. · #8 03/18/2007, 11:44 AM

So far it seems everyone directs their fans differently. What I am wondering is which way is the most effective way that keeps the temp down the most and which way causes less wear on the fans. Yesterday I tried running both fans out and by doing so I noticed that this keep the temp down more that blowing both in. Have not tried one in and one out yet.
I appreciate your responses.

zoomfish1 · #9 03/18/2007, 01:48 PM

I had 2 blowing in and the temp crept up to 82-83. I just changed to 1 in and 1 out and temp has not gotten above 80. That is my target temp so I would say that works the best.

bbehring · #10 03/18/2007, 02:03 PM

Not to highjack here but what about fans in an understand sump? I find heat builds in my stand and if I keep the center door open, the tank cools between 1 to 2 degrees. What about 1 fan in and 1 fan out? Was concerned about pulling dust in across the sump?

eddybabyhd · #11 03/18/2007, 03:34 PM

honestly it depends on what type of heat you are trying to remove. If you remove the heat from the air in the canopy by both blowing out then you effectivly reduce the rate at which the water evaporates. On the other hand there are people (im sure reading this) who will tell you that evaporative cooling is better, (fans blowing across the water surface. I would rather have the heat extracted from my canopy, then to have the temp swings of evap cooling. Not saying my tank doesnt swing, cause it does .Its just does it alot less if you remove the heat from the canopy.

There is my 2 cents

D.G. · #12 03/18/2007, 04:08 PM

Ed,
That is what I am thinking. It would make sense to remove heat from upper surface of water in order to cool it down. I have not run my two fans out long enough to see how fast the water evaporates. It does seem that everyone has their own preference.

eddybabyhd · #13 03/18/2007, 06:44 PM

for me the fans blowing out works better. And to be honest i dont have a problem with mine getting rusted for covered with salt creep. I did when i had one in and one out though. You got it figured out

Travis L. Stevens · #14 03/19/2007, 08:42 AM

For me I have one large fan blowing in on my MH in the canopy, and I have a centrifugal fan blowing across the top of my water over my sump/fuge. They are the little, cheap ones that you can pickup at WalMart. Man do they move a lot of air as quiet as possible. It keeps my 250w MH powered 29g tank cool to 80ºF (lower if I want).

D.G. · #15 03/19/2007, 08:55 AM

Is you canopy opened where the large fan blows straight through?

Travis L. Stevens · #16 03/19/2007, 09:09 AM

It has an open back and holes on each end for two fans. I just only have one fan in it though. It keeps the ambient heat from the metal halide out and away from the tank. I have a blower style centrifugal fan blowing across the sump/fuge for real cooling. The largest downside to pushing as much air as I do is I evaporate 2-2.5 gallons of water a day.

manitou74 · #17 03/19/2007, 05:34 PM

I have a closed canopy. 2 - 175 watt 10k MH and 2 VHO actinic. I have two 4x4 fans mounted in the canopy. One blows in the other exhausts out. They are tied to the MH lights so they are only on when the MH's are on. In the heat of the summer I blow an 8" fan from Wally World across the water and get the same evaportaion as Travis. I have not tried blowing it across the sump. Has anyone determined if blowing across the sump or the top of the tank give you better temp control?

Here is a tip I learned the hard way. No matter what you do, don't exhaust your air near your home thermostat. Not only will it put some salt creep in it, but it will cause you house A/C to run more.

bbehring · #18 03/19/2007, 10:40 PM

Travis, what is the exact fan from Walmart you have blowing across your sump/fuge?

Travis L. Stevens · #19 03/20/2007, 08:58 AM

manitou74: I used to have it mounted to blow into my canopy, and it didn't have the same amount of cooling as it did under my sump. But your milage may vary.

bbehring: I've been searching online for it for quite a while and haven't been able to find it. It is a tiny version of this:

jeeperrs · #20 03/20/2007, 10:28 AM

I am gonna look for one of those at walmart today

Travis L. Stevens · #21 03/20/2007, 10:38 AM

Quote:

Originally posted by jeeperrs
I am gonna look for one of those at walmart today

FWIW, I was looking for them about three days ago, and they don't seem to be carrying them this year. Who knows though, it's still Spring.

mskohl · #22 03/20/2007, 10:46 AM

I had a clip on fan blowing across my fuge and nothing on the lights. My lights were PCs though, so they don't put out the amount of heat a MH will. Also, this tank doesn't have a canopy around the lights, so my heat was building up in the stand.

The little clip on fan really helped to control the temp during the day. It's enough cooling that it dropped the temp too cool at night and had to be turned off.

I had a similar experience with a canopy of t5s. The clip on fan cooled more than enough. It's not the prettiest, so if it's visible, I might choose something else, but in a pinch, it works great.

jkhudson · #23 03/20/2007, 01:31 PM

I run 2 in and 2 out.

D.G. · #24 03/20/2007, 02:36 PM

What size are your fans and on what size tank?

Prater · #25 03/20/2007, 02:37 PM

Get fancy and fabricate yor hood to use PPV. Positive Pressure Ventalation. Never used it on a tank, but have used it to clear smoke from buildings many times in fire training...

You would have to seal your hood and use a turbo fan blowing in. Then have an outlet that is smaller than the inlet and it will create a vacuum in the hood causing all the heated air to evacuate as fresh clean air is blown in.

Not practical for our tanks, but may be fun for someone to experiment with.