Fans, fans, and more fans

I bought two diffrent fans...
1. 8" in line duct fan with 500 CFM from home depot made by suncourt (using to cool down room temp)
2. 6" centrifugal 435 CFM from local hydro store made by valueline (using to cool down cool tube)

my problem is the 1st one is extremely quiet but does not bring in enough air, so i have two of them. The 2nd one is so loud but pushes in a lot more air. This make no since to me because The 1st one has more CFM's than the 2nd. Why?

Is there another brand that will cool down a cool tube and be much quieter?

If not how can i make the fan more quiet?

Thanks...

Not sure but maybe a bump will help.

If the inline fans have to move air through a filter or any ducting, that will seriously impair their performance. Axial type fans don't cope well at all with static pressure, they are designed for free air movement, so any restriction on the flow will cause cfms to drop drastically below the rating.
Centrifugal fans are much better, but as you've found out, they can be quite noisy. If the noise is from vibrations it can be lessened by building a box around the fan and filling it with foam padding, and either mount the fan using rubber between the mounting surface and the fan brackets, or hang it from bungee cords. Another way to reduce the noise is with a fan speed controller, a fan running at 90% of full power may make half as much noise as if it was running flat out.
You say the fans are blowing air in, this is not the right way to use them. Air should be extracted from the room, not blown in. If you have the fan pushing air in, you are pressurizing the room, and causing air (and smell) to leak out from any gaps in the construction. Also when the pressure of a gas is increased, so does the temperature. You are much better off sucking air out, then blowing it as far away from the grow area as practical while keeping ducting as short as possible.
If you leave a hole for the intake slightly smaller than the exhaust, this will create a small amount of negative pressure, keeping odours from leaking out of the room.

1. - You have some kind of passive room exhaust, right? I have a window fan going most of the time and if I don't crack my door, I'm not getting much airflow despite how much air the fan is capable of blowing.

2. - You could build an enclosure for the fan with some plywood and some kind of sound-deadening material inside. I covered mine with a bunch of old t-shirts and it noticeably decreased the volume, but not as much as an enclosure would. Unless a passerby can hear fan noise outside your place, I suggest getting used to the sound of whirring fan(s). I have.

I use a 4in 225 cfm sunleaves wind tunnel inline fan. super quiet and pushes ALOT of air. and only $125!

check these out.... they move tons of air and the only sound is from all the moving air.



http://www.hvacquick.com/spfnconfig.php?fm=td

good luck
mustang

I just use a fan to blow air around the room and that's it. I don't even really know why I have it in there.