Sucking? Or Blowing?

[Harley387]

Not sure which way to mount my cooling fans. Blowing air out of canopy? Or sucking air into canopy? Or perhaps one sucking one blowing? Suggetsions?

 

[NateHanson]

Moved to DIY forum. (show that DIY some love folks! )

I've heard some say that blowing is better because the fans don't wear out as quickly since they're not moving salt-spray, just fresh air. Others have one blowing in one blowing out.

 

[Armando]

You need one fan to pull air in (blow) and another fan to blow air out (suck).

They should be placed in opposite sides of the canopy otherwise you'll just create an air short circuit and it will not cool down the canopy.

 

[SMS76]

Also depends on what do you have in your canopy? MH, how many and what wattage also what size? If you are doing 400Watt on 75G tank then it would be better to have more then one fan, each type.
Nate is right, i had one fan that was blowing out and it was getting salt creep etc... I would prefer to have one that's blowing in but that might potenitially get other polutions etc.. in your tank as well...

 

[_Eric_]

I've heard some say that blowing is better because the fans don't wear out as quickly since they're not moving salt-spray, just fresh air.

I have all 7 fans blowing into the canopy. (No saltcreep EVER)

 

[Casino]

I guess it will also depend if you have an open back canopy. I have an open back and I have both of my fans blowing in. It it was an entirely closed canopy I would think you need one to blow air in and another one to suck the air out.

 

[chuck]

if you have an open back canopy it shouldn't matter which way the fans are going. The area will only hold so much air. So, if you have an open canopy, and fans last longer blowing in, then that is what I would do. Then again, I am a newbie.

 

[Rays]

I've got 2 250's, and 2 110 actinics in enclosed canopy, one fan in one fan out.

 

[Richard]

I have 2 x 175MH on my 29gal and both blowing out.Are you confused yet?

 

[Harley387]

Ok..OK....I have 2X250 MH and 2X110 VHO actinics. The back of the canopy is open. Best scenario???

 

[NateHanson]

I'd say if the back is open, put two fans on the sides, both blowing in.

Nate

 

[Member No. 1]

I'd say if the back is open, put two fans on the sides, both blowing in.

Nate

What Nate said!
Think of this, open back, if you have the fans blowing out then there is a good chance of only pulling air around the fan. But blowing in, you have more of a chance of blowing cool air the entire lenght of the lamp. Also it will move air around the MH better.

 

[Jim Tansey]

It all depends on the canopy design, mine is open back and wood grill top with two 250W MH and two 110W VHO's on a 75, my tank runs 2 degrees cooler with both fans blowing in (I tried it all ways).

Jim

 

[Casino]

Yeah. My fans are blowing directly into a 250w MH with an open back canopy. It also helps with evaporation.

 

[Armando]

You need one fan to pull air in (blow) and another fan to blow air out (suck).

They should be placed in opposite sides of the canopy otherwise you'll just create an air short circuit and it will not cool down the canopy.

that applies only to closed canopies. if you have open canopy than it's what other posts say.

 

[NateHanson]

I also assume that fans have performance similarities to centrifugal pumps (which operate under similar principles, right engineers?) in which case the fan will move more air if the outlet is restricted rather than the inlet restricted. So with all else equal, pressurizing the hood, rather than sucking out of the hood, would be more efficient.

Does that follow?