What kind of fans to put in a hood?

120mm fans are usually quieter since they can run at lower RPMs. You can also slow the 120mm fans down further with a $5 variable voltage power supply thereby reducing the CFM and evaporation.
4- 1" holes will not give you anywhere near the surface area of a single 4" hole or even a couple of 2" or 3" holes. If my math is right it would take 16- 1" holes to equal the surface area of a single 4" (120mm) fan. You want at least equal surface area or you create back pressure and move much less air due to resistance.
 
I got 4 120mm fans for my hood over my 55g. The reason you want 120mm is they move more air while also being quieter than the smaller ones that run at higher velocity. If you want smaller fans, make sure to find the noise rating of the fan. Try to stay under 25db if possible. If you don't want 120mm due to the size, I'd go for 80mm.

You can hook them up to a variable voltage DC plug. I got one from Radio Shack that's 3-12v. Lowering this switch will decrease fan velocity (and noise).

You'll need to splice the cords for both the DC adapter and the fans and wire them together. You'll likely have an extra (blue, I think) wire from the fan that isn't used. It's used by motherboards to control fan speed. The fans will have an amperage rating. The DC adapter will also have an amperage rating, usually between 600 and 1000 milliamps. You can hook multiple fans up to one DC adapter, provided the amperage requirements of the fans combined do not add up to more than the DC adapter supplies. Try to make sure the adapter provides more amperage than is needed by the fans. On the fans, the amperage may be listed as a decimal, like .12 Amps. This is the same as 120 milliamps.

I'd use wire nuts and electrical tape to connect the wires. Make sure they don't hang down into a place where water can drip down the cord. There's probably safer ways to connect wires in situations where water is nearby, though.
 
Connect them with butt splice (crimp) connectors and shrink tube for a good tight water resistant splice. The odd wire is usually yellow on the Vantecs, you just ignore it and use the red and black wires. I always do a temp splice first to ensure the fans have the right rotation, ie blowing in and not out, before I make the permanent splice.
 
So your saying cut 2 - 4" holes in the back and that should stop any back pressure?

If I put the fans on the right and the left on the bottom, should I then put the exit holes at the top left and right, or the top middle?

Which is more effective, or it really doesnt matter?
 
I would put them closer to the middle so the air has to travel at least half way across the tank and lights before exiting.
 
Ok I'm about to build my hood and need to figure out exactly what I'm going to do.

do you think 1 fan in the middle of my 36" 40 breeder is enough? Or one on each side would be better?

I checked new egg for vantec, and I couldn't find any stealth, just the following...

http://www.newegg.com/Product/Product.aspx?Item=N82E16811999614

http://www.newegg.com/Product/Product.aspx?Item=N82E16835110014

The first one has a dba noise level of 28, and the second one has a noise level of 29-39, so the first one is quieter right?

And it's cheaper too.

But are the stealth ones quieter than 28 dba?

Where do I find one of these $5 variable voltage power supplies?
 
The first ones the SF are Stealths, the second ones are Thermo flows. Power supplies can be found at Radio Shack, WalMart or Frys Electronics. I got all of mine at Harbor Freight Tools but the internet shows they no longer carry them?
 
alright what do you think about putting just a single fan in the middle as opposed to two fans on either side of the tank?

It's only a 40 breeder which is 36" long.

I am only have one - 175W single ended MH with a lumenarc reflector.

So since I am only having one bulb as opposed to a normal 2 bulb set up on most sytems, maybe 2 fans is a bit overkill?

I would then cut two - 2" holes in the top cornes to take advantage of convection.
 
I think you will end up with dead spots on the ends. How about a fan in one end with a hole in the opposite side or a fan in back but as close as possible to one end with the air exits on top at the extreme opposite end?
 
all of the designs will work, but which one do you think will be most effective?

You really think there will be dead spots with a single fan in the middle? I assumed it would deflect off the front part of the hood and roll along the sides to the back, up to the top and out the holes.

The opposite corner one will work too, but will it be an equal air flow like putting it in the middle?

Or should I just go with 2 fans on each end and just lower the rpms down in order to knock my rate of evaporation down as well?
 
I prefer two fans but if thats not what you want I would recommend a fan on one end and exit on the other so air has to travel the length of the tank.
 
I guess since I will have the variable voltage power supply, two fans is doable with out overkilling it, yet making it extremely effective.

Is it easy to reduce the power on these things? What is it just a little dial or something to turn?
 
Yes, thye have a little knob or screwdriver slot that adjusts in 1.5V increments from 0 to 12 volts. I use 12v in the summer and either 9 or 10.5v in the winter when I do not need as much cooling since the house is cooler.
 
<a href=showthread.php?s=&postid=10687490#post10687490 target=_blank>Originally posted</a> by agoutihead
I guess since I will have the variable voltage power supply, two fans is doable with out overkilling it, yet making it extremely effective.

Is it easy to reduce the power on these things? What is it just a little dial or something to turn?
Click to expand...



So what did you decide?
 
I haven't had any funds lately, so I haven't done anything. I'm planning on putting the two fans with the two exit holes that are equal size.

For now I just keep the front of my hood open so that the heat doesn't stay inside.

With the 175W, it doesn't really get super hot, which I am quite happy about.

When I do get around to it, I'll post some pics.
 
Wow they are much cheaper than the Vantec stealths.

But what is the difference in the 120mm fan for 5.95 and the one for 3.95?

How do they compare to the vantec stealths in noise?

Has anyone else used them?

If the 3.95 ones are silent, I can probably buy them today as they are a great deal!
 
The closed corners are solid between the screw holes on front and back. The open just have a hole in the top and bottom and a gap in between. Some cases and big heatsinks need a open corner for mounting.
If you go
HERE and look half way down the page they show what I'm talking about.
Jab Tech is a good place also, I'm spent a ton of money with them.

EDIT: HERE is a detailed review of some very good fans including the Yate Loons
If you want to spend the money the best fan out there is the Sanyo Denki San Ace big and quiet and moves a ton of air, its what I run on my CPU cooler. They are louder than the Yate's but if you 7v them they are very quiet.
 
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