Help Me With Air Flow In My Canopy

hey yea that's what I have. 2 120mm Yate Loons and a dual Azoo. You can touch the reflectors without getting burned (unless you touch the glass)

Dude I think I may go back out tonight. It's cinco de mayo in New Orleans, so many hotties out it's not even funny. Woooot!!!!!!

 

dude you should.. Be sure to go to Pat-O's and have a $10 Hurricane.. I bet the weather is perfect for that outside patio.. If not there, ricks is open late. lol..

 

Oh yea. I really like NOLA. I prefer it to Vegas, actually - both are great, but the atmosphere is more enjoyable if you ask me. Plus the food is the bomb diggity! I had some oysters and crab cakes tonight that were killer. I've been knockin back the dark beers from Beerfest and jack and cokes all night.

 

The weather is choice. I'm not a big fan of sweet mixed drinks - I can do some, but usually I stick to beers and straight up hard liquor shots or whiskey / rum mixed with coke. Most sweet drinks make me ill.

 

I base my opinion on observing what engineers have done. I'm not nearly smart enough to design such things. Luckily I can examine my Coralife fixture, and motors in the field at work--and be confident that the folks who designed both items WERE engineers; and I can assume they know worlds more than I do about heat exchange and cooling hot objects.

Here's what I see around me:

A. In industry, almost without exception, contained areas to be cooled by moving air are almost always cooled by blowing ambient air into the enclosure from outside, rather then attempting to suck hot air out.
B. In my Coralife halide fixture, there is one single fan blowing air into the enclosure top center, and passive vents on either side of the unit. When I put my hands on the sides of the unit, I feel warm air coming out.
C. Although I've yet to see an exhaust fan on any enclosure (like a motor, for example), there is always a venting mechanism for air pressure to equalize (warm air escapes from the lower pressure area).

Here's what I gather from these scenarios. First it is more important to introduce cooler outside air than it is to exhaust internal hot air. Secondly, the lack of exhaust fans must be equalized by exit opening(s) of sufficient size. Given enough cooler air entering the enclosure, the warmer air will leave on its own by the difference in pressures. The fans inputting air will increase air pressure, and the escaping air will contain a good deal of the heat which was generated inside the enclosure.

Back to your scenario, Tatted--I think option B would be far less efficient. For the reason I gave above, I'm comfortable making the assumption. If exhausting heat was as efficient as introducing cool--then my light fixture would have fans expelling air on the sides, but it doesn't. Also, motors would have an introduction fan, and an exhaust fan; but they don't.

Here's another way to think about it. If you had a lightbulb in a shoebox with only one hole and had to put a fan in that hole--which direction would you point the fan and why? AFAIK, engineers have answered that question for me.

 

Great post Sparky!!!

Which will keep me leaning towards the two on each side blowing in with ventilation holes in the ceiling....

I must get this right the first time since I will be drilling holes that will be permanent...

I will be drilling probably a 12" x 12" area of all 1" holes that should give me a 100 1" holes if spaced properly may have to drop down to 3/4" holes. Which will hopefully give me plenty of vent holes for air to rise and escape out of...

I just dont want to end up later saying "I should have done it this or that way."

 

I imagine that in industry, you're dealing with much different flow dynamics than in a small enclosure; one reason is likely the raw air to energy output ratio of a factory compared to a light fixture. Most small electronic devices (XBox 360, PS3, my 6-bulb T5 unit) have equal flow in as out.

The 360 and PS3 both have one fan on each side. One flows in, one flows out. A Wii, interestingly, has only one fan flowing out; this is with a very small amount of heat to dissipate, however.

My Alienware computer (with their cooling system, and a 600 watt draw) has 3 small fans + the PSU outlet (hot air) in, and two fans (one big, one equal sized as the inlet fans) out on the case, with the 2 GPU fans using rear slots as outlets.

The T5 fixture on my tank has 2 fans in on the left, 2 fans out on the right.

I mean, I know that well-designed in-only or out-only systems will trump an in-and-out system, but in-and-out with equivalent flow should be the easiest way to achieve optimal flow, if you don't mind the 3 extra watts used by the extra fans.

 

I have one 4" fan on each side of my canopy that turn on with the daylights but I have an open back and I leave the half top open. With no escape in your situation I would do the two fans on each side or one fan on each side and two on the back wall and consider cutting one, two, three or four square or round hole in the back or top. I really feel you only need one fan blowing out if you keep it closed or all blowing in with vents. I have pics of mine for my 210.
I have my T5's on a sliding shelf that I built inside my 15" canopy. I am considering adding two more fans to cool down things more.

 

If it were my tank I would probably look at dropping each halide a half inch or so and mount exhaust fans right above them with the fans on the outside of your canopy. Then have a fan on either side pulling air cool air in. Not sure if its the best way, nor do I claim it to be, but that's the approach I would take. I did something similar to my nano and have never gone over 80*.

~Will.

 

Tat....You asked for experience on this one...so here goes. I dont know if you followed my canopy/halide build, but I am running almost the identicle set-up, but the back of mine is open. I am running one 4" on each side of the canopy, blowing in. I am running 3 120mm fans in the rear, blowing out. That said. Those rear fans blowing out, remove a bunch of heat. I would not dare let it self vent. It would not escape near fast enough. Yours is closed in, so it would be worse. If I had to do something different, I probably would have had 2 fans on each side instead of one. It works ok though. Find my build thread. there are alot of pics. If not, I will post it for you. I can appreciate everyone's theory on self venting, but it will not be enough...trust me. I would run 2 on each side, and at least 3 on top pulling heat out...Good Luck!!..If not an option...I would go with option 2.