vent problem, too loud coming from cooltube.

[luxx]

400w hps, cooltubed, with a 170 cfm htg fan.

The fan itself isn't loud at all as it is in the attic, just the sucking sound, it is soo, loud. The room is only 3x3, so...

Should i get a fan controller?
Should i run another tube back up to the top of the room?
Is there some sort of baffle that i can use that doesn't restrict airflow?

thanks in advance..

 

[FreakNature]

A 170 CFM exhaust fan pulls 865.8 feet per minute through a 6" duct (or a velocity of 14.43 feet per second). This is in the upper range for normally accepted velocities to limit noise. Adding another 6" duct or changing to an 8" or 10" duct would decrease the noise in the duct, but you're still limited by the 6" collar on the cooltube, so the noise probably wouldn't change. Sound attenuators are available (google that), but probably large and expensive. Maybe a fan controller to cut the speed in half would be best. I don't think heat would be a problem since you have the cooltube, but what's your temperature now with the light on?

 

[luxx]

well all the tubing is 4'' the cooltube is 6'' with a 6''to4'' converter. so your saying one of my options is to make my tubing bigger.. ok, sounds good, lets leave that option on the back-burner due to my funds running low..

as far as temp, i dont know, just built the room today, i guess ill fire it up and put a thermometer in there. i hate to use the electricity for a test though.. lets say they will be fine, considering the intake is going to be coming from the crawlspace (extremely cold even in summer)

would you know the formula to calculate cfms needed in a certain amount of space?

thanks for stopping by my journal, btw

 

[luxx]

here is some pics to reference.

cant hear a thing from up here....

heres our source of noise pollution, the intake on the cooltube...

 

[dom42]

they way that i alway set up air cooled lights is i always hav the ducting as one unit. Meaning i would grab an intake from the floor through the lights the exhaust into an attic or such. Then i hav a seperate exhaust/ intake for the actually grow room.

I know this probably doesn't help but just an idea. That way you don't get that sucking noise from your lights. And you will also hav the option to run a CO2 generator(ofcourse you'd want a CO2 controller to control when exhaust kicks in so you don't waste it).

 

[luxx]

i am going to bump this, i have my finger on the buy it now on this item:

Speed Controller control Centrifugal Inline Exhaust Fan - eBay (item 390142927847 end time Mar-14-10 0811 PDT)


do i need this one, or can i use the cheap ones that you can get at lowes, homedepot?

 

[luxx]

got it, ill let you know how much it helps.

 

[FreakNature]

well all the tubing is 4'' the cooltube is 6'' with a 6''to4'' converter. so your saying one of my options is to make my tubing bigger.. ok, sounds good, lets leave that option on the back-burner due to my funds running low..

as far as temp, i dont know, just built the room today, i guess ill fire it up and put a thermometer in there. i hate to use the electricity for a test though.. lets say they will be fine, considering the intake is going to be coming from the crawlspace (extremely cold even in summer)

would you know the formula to calculate cfms needed in a certain amount of space?

thanks for stopping by my journal, btw

Well since you have the fan at a certain speed and the cooltube collar is 6", changing the duct size may not help enough. I don't know about the quality or utility of the fan controller...sometimes slowing a fan down causes it's own noise. The manufacturer of the fan should be able to provide the operating range for the fan.

There used to (and may still) be a thread on this site where someone had a pretty complex formula for determining required exhaust rates based on lighting, room size, incoming air temps (probably around 52 F if coming from under your floor)...but I searched and must not used the right terms.

 

[luxx]

3x3x7 = 63 ft cubed
63ft3 x 3 (times to move air in a min) = 189
someone says to take your watts of lights and equipment in my case 400 and divide by 4 which is 100, then add that to the total = 289 cfms, great.
i have a 170, might have to add another fan, which is wonderful, all i need is more noise.
fan and filter

fan controller

no matter what i do or how much i research, ive been wrong about this from day one.

havent got the controller yet, so i wont know the temps i can handle.

(would having too small of a intake cause the air to be louder coming from the exhaust?)

 

[ChicagoJoe]

Luxx, here's my green take. What do you (and you all) think?

I thought your carbon filter pictured is made to draw air in thru the pre-filter (the white outer layer) that traps the large particles in the air before hitting the carbon (making it last longer). The whole filter acts as a sound dampener.

It looks like you have it set up differently, blowing air thru the filter, so it goes straight to the carbon unfiltered and then exits the filter thru the pre-filter.

If you have space in the grow area, couldn't you place the filter in there so you can pull the air first thru the filter, then thru the cool tube then to the attic and thru the fan.

I'm thinking this will completely get rid of your whooshing sound.

 

[luxx]

Luxx, here's my green take. What do you (and you all) think?

I thought your carbon filter pictured is made to draw air in thru the pre-filter (the white outer layer) that traps the large particles in the air before hitting the carbon (making it last longer). The whole filter acts as a sound dampener.

It looks like you have it set up differently, blowing air thru the filter, so it goes straight to the carbon unfiltered and then exits the filter thru the pre-filter.

If you have space in the grow area, couldn't you place the filter in there so you can pull the air first thru the filter, then thru the cool tube then to the attic and thru the fan.

I'm thinking this will completely get rid of your whooshing sound.

well, ive googled my ass off, and you are right, this weekend, ill have to unseal everything, pull it down, and put it somewhere high(3x3x7)

need to get more ducting though

so leave my fan the way it is, take the scrubber down, run a duct from the other side of the cooltube, insert the scrubber, done. right?
ChicagoJoe +rep

 

[ChicagoJoe]

well, ive googled my ass off, and you are right, this weekend, ill have to unseal everything, pull it down, and put it somewhere high(3x3x7)

need to get more ducting though

so leave my fan the way it is, take the scrubber down, run a duct from the other side of the cooltube, insert the scrubber, done. right?
ChicagoJoe +rep

wow luxx, you made my day brother,
thanks for the reps and good luck to you.

-> = airflow


-> scrubber -> ducting -> cool tube -> ducting -> fan -> exhaust to attic

 

[FreakNature]

luxx, just another thought - if you put enough exhaust in to handle your heat (whatever that calculation is) I would think it would be enough...period. There is no hard and fast rule about number of air changes in a grow room. If you replace all of the air in the room 2-3 times a minute that's got to be plenty. It still represents a constant flow of fresh air. The exhaust fan doesn't need to accommodate the circulation of air in the room, a small reciprocating fan is ok for that.