question about proper exhaust

[dirkdaddy]

I'm getting a secret jardine dr80 (2'8" x 2'8" x 5'3") with a 400w super sun 2 hps light and I have some questions on exhaust. I am planning on running 6" ducting from the light, out one of the top exhausts, through the attic, and having my 4" vortex + can33 filter in the attic. couple of questions.

first, is the 4" going to be enough cfm to suit my needs (based on the square footage plus the light) or do I need to get the 6"? the ducting won't be running more than a couple of feet. ambient temps in the area are around 75-76f.

second, can anyone link me to either a grow diary, post, or something that has a good write up/pictures of an insulated rubbermaid exhaust box? i've searched a while for one and I can't find a good example. like one that would house a vortex plus a carbon filter and reduce the sound a bit. also, is having my fan and filter completely removed from the tent an issue or is it a good thing? only ducting will be running from the tent while the fan and filter sit in the attic to exhaust.

I was thinking of alternative ways to set it up and I don't know if it would make more sense to mount the fan inside the tent and having ducting run through the attic from the fan and attach to only the filter in the attic. or is it better to keep the fan/filter together and away?

 

[G33k Speak]

For the box- some have used blankets, 'egg crate foam', and expandable foam from a can.
Insulated ducting may also help.

The 4 inch should be fine for a 400W. You can add glass if you want. don't seal the reflector, but let the fan pull the room air thru the reflector on it's way out.

Remeber, you're sucking your inside air to the outside, so that means you're sucking your AC'ed air out of the house at 160 cubic feet a minute.

 

[FreezerBoy]

If the attic is available, I'd put the filter in the tent and the fan in the attic. This will go a long way to suppress noise though you may still want to muffle it. The fan only needs a couple drops of oil once a year. A filter will need to be replenished or replaced several times a year.

 

[dirkdaddy]

For the box- some have used blankets, 'egg crate foam', and expandable foam from a can.
Insulated ducting may also help.

The 4 inch should be fine for a 400W. You can add glass if you want. don't seal the reflector, but let the fan pull the room air thru the reflector on it's way out.

Remeber, you're sucking your inside air to the outside, so that means you're sucking your AC'ed air out of the house at 160 cubic feet a minute.

I got that. Is the volume of AC'ed air being removed a problem or something? I could easily vent the hot air back into the room but its going to be in a 4x12 (rough estimate) rectangular shaped closet with no a/c vents except for right outside the door. I figured it would eventually get to too hot in the room to be effective with the 400watter but I could be mistaken. and I am planning on just leaving one end of the light open for suction

and the vents at the bottom of the tent will be the passive intake. and from what I can tell there is glass already in the reflector and for the most part it is sealed except for the two 6" vents. thanks for the help

 

[dirkdaddy]

If the attic is available, I'd put the filter in the tent and the fan in the attic. This will go a long way to suppress noise though you may still want to muffle it. The fan only needs a couple drops of oil once a year. A filter will need to be replenished or replaced several times a year.

how do you rig it like that? I am trying to picture it in my head and I can't for some reason. I picture it right now going something like this:

6" vent on light ----> 6" ducting all the way to 6" to 4" reducer to the fan ----> then the fan/filter connected with the fan blowing out the filter

the problem I see is how do I get the ducting hooked up the light to connect to the filter and pass through to the fan? as far as I can tell filters only have one "input" on them while the other end is sealed. sorry if I am just being dense.

edit: nevermind, I think I figured it out. I am guessing this is the set up I should be doing but with the fan in the attic. can stinky air not get sucked through the light? thanks for the suggestion

 

[eyes]

the fan and filter together is better in the tent.ive never blown through a carbon filter b4 to see the how effective that is.If noise is an issue,seal the fan or wrap in egg crate and use a speed controler(a good one),to slow the fan down to like 80 cfm from 140.i see your point dont want to lose all the ac through the filter,then cool the light and up the attic.well,not only will you cool the tent with a/c from the intake,youd also be cooling the light and exhausting smell.THe ac has to run to cool the room the tent is in anyway.so,as its cooling the room it will cool your tent.when the ac kicks off,the filter will still be running keeping smells at bay and cooling the light at all times.id run the filter 24/7.you have to run the ac in the room regardless cause if its humid outside you cant be drawing in that humid air to get rid of humid air.am i gettng anywhere?

 

[FreezerBoy]

edit: nevermind, I think I figured it out. I am guessing this is the set up I should be doing but with the fan in the attic. can stinky air not get sucked through the light? thanks for the suggestion

If you were to do this it would require enclosing the hood with glass to force all air through the filter.

My concerns were space and noise. A 4" fan is about 12" in diameter. I don't know about you but, I don't have 12" to spare. My Elicent (5-10dB quieter than your Vortex) was quadruple silenced with, speed control, insulated ducting, fan isolation box and muffler. it was, with the garage door open, still audible from the back of my garage to the end of my driveway, across the street and to my neighbors door. Not ear bleeding loud, just barely loud in an incredibly annoying way. There was simply no excuse for a noise of that type to exist in a residential neighborhood.

Once the garage door was closed, the fan was no longer audible in the driveway or the house. Moral of the story: keep the fan in a room where no one is allowed to go.

 

[dirkdaddy]

i'm thinking that pushing the air through the filter may be a better idea despite the general consensus that pulling is better. i've read that by pushing the air through the filter it creates a natural muffler and eliminates the loud "whoose" produced by open flanges/ducts and moving air which is normally what the sound is coming from a vortex (or so i've read).

any opinions on that? hell, maybe i'll just set it up both ways to see what the difference is but it seems like the performance loss is negligible when pushing out through the filter so I may just set it up that way from the start.

 

[G33k Speak]

I second the vote for putting the fan in the attic. I had to do that because of lack of room. Juct run a flexi hose down into the room. There may be a pic in my gallery.

put the can on the exaust side of the fan, and suck the air through the hood in the room.- the glass might allow you to get the light closer to the plants- esp if you have a lowish ceiling.

 

[whatissixbynine]

.

 

[mayorofthdesert]

I'd advise against putting the fan in the attic with the filter in the tent, ESPECIALLY if there is plenty of negative pressure. I came home from a week away to find that my fan in the attic had somehow peeled the clear inner lining off the inside of the duct and sealed it solid. I'm lucky the fan didn't burn itself up and the house down. Put the fan & filter in the attic together and save some space in the tent too.

 

[FreezerBoy]

Good "heads up" to keep an eye out for but, filter placement does not remove or secure the lining from the duct.

 

[mayorofthdesert]

Good "heads up" to keep an eye out for but, filter placement does not remove or secure the lining from the duct.

You're correct, I'm sure there was an opening of some sort in the duct's main skin. I did push and pull it through some tight spots, I'm guessing I tore it in the process but I couldn't see anything obvious. AND my cabine'ts intake was partially blocked. Still plenty of flow, but more negative pressure than just a carbon filter. Didn;t mean to mislead, just hadn't given it much more thought after I fixed it & moved the filter up to the attic with the fan. I'm sure tons of folks have their exhausts set up the way I did with no issues - we'd be hearing about it a lot if not...