4" inline duct fan is it enough?

Discussion in 'Do It Yourself' started by freegrow11, May 4, 2011.

  1. Hi all, I'm starting very shortly and im just getting everything together for my room. Ive got a can-filter 2600 for a carbon filter and im wondering if a 4" inline duct fan @ 65 cfm free flow is good enough to clear a room 1.5x1.8x4. I did the cfm math and it seems we need very very little cfm, but will it be able to pull through a small portion of ducting (1.5feet max) as well?
  2. As long as it doesn't go through carbon it should be okay. Even at half the rated CFM it should be okay as long as the only job is to exchange air without having to do any "work" that would require static pressure.
  3. #3 freegrow11, May 4, 2011
    Last edited by a moderator: May 4, 2011
    it would be attached to the carbon filter pulling air and pushing it down ducting.

    also, I have a 120mm computer fan @ 110cfm, static pressure 2.30mmAq.. would that be better off then the duct booster?

  4. I would try both but neither will work most likely.
  5. What if I completly remove the ducting and just have either of the fans exausting the carbon filter?.. It does say on the can filter site "recommended fan 4" axial computer fan". Is ducting the only problem or is it static pressure period?

  6. I'm not as concerned with a short duct run as I am the static pressure to push it through the carbon. Give it a try though you can always replace the fan.
  7. hmm, well I guess its all ive got. Most likely im going to bring back the duct booster... it really feels like the computer fan sucks ALOT more air than the duct booster. I will test both out and post my the verdict
  8. Since you have both, use both if possible.

    The 4" fans don't move much air, and have very little static pressure. The fan needs to be able to over come the restriction of air from the filter, and any duct run afterwards. (
    Pushing against a short duct run (1.5ft) will be fine (low static pressure drop) - I am not sure about the carbon filter pressure drop on that fan - smell is not an issue for me.

    How is your lighting setup?

    Try both and see what works for you.
  9. I cant dish the money to get a 120$ fan. I attached the inline duct fan and did a small test.. it seems to be working decently well. I will do another longer test tomorrow just to make sure. I won't be running any ducting, just venting outside my grow room
  10. I emailed the can filter website and they responded today with this....

    "The axial fan rated for 100 cfm will pull aprx. 40 cfm through the filter.

    They lose 60% of the air flow through a filter."

    I did ask about static pressure and he didnt say anything about that. I figure as long as there is no ducting axial fans apparently work fine if u have the cfm. Im trying a better test today with my induct fan @ 80cfm I will post after with the results

  11. Please keep us posted for those in a similar bind.
  12. So I ran a test today on a room 1.5'x1.8'x4' with a candle (french vanilla vry potent).... Let the candle burn for about 20min and couldnt smell anything at all directly outside the room. I then pulled a small portion of the plastic off at the bottom and still could not smell anything, pulled down all the plastic and left the candle for another 20min just burning off into the entire closet and when I checked it I had to be directly above the candle to be able to smell it.

    4" inline duct fan @ 80 CFM + Can filter 2600 ---- VERIFIED

    though I am not a scientist I think it does kinda prove that you can use these small fans in smaller sized rooms.. I really think a computer fan would also work as long as its a small room, it has some good cfm, and at least decent static pressure.
  13. Are you talking about the duct fans you can buy at Home Depot? How loud is it?
  14. I would imagine home depot has the same ones, I got mine at home hardware because home depot dosnt have them in my area :(.. Its a little loud, but I dont have a flange on the carbon filter that would probably keep it from virbrating. I muffled it with those triangle bed sheet things and now it sounds more like a computer, just air flowing. I will have a loud computer in the room so it will mask the sound easily with the closet door shut.

    it was about 40$ for the induct fan.
  15. #16 jollyrancher1, May 6, 2011
    Last edited by a moderator: May 6, 2011
    You are talking about venting 11 cu ft with an 80 cu ft a min fan.

    So the volume is exchanged once every 7 seconds approx?

    I would hope you couldn't smell anything.

    That isn't a room, that is a box.:rolleyes:

    For testing I use incense, but your method works to.
  16. LOL:D I knew I had enough CFM, but I wasn't sure if it would pull through a can filter. If u search everywhere on this site about a carbon filter + computer fan or induct fan... all you hear is no u cant do it or that it wont work well... but it does work for smaller rooms as long as u have a good amount of CFM. The can filter ppl said the filter will reduce cfm by 60% so from 80cfm that gives me 32cfm which is way more then enough for my little room. From my research it seemed like ppl thought it litterally will not pull through the filter.
    Also if u look at my first couple posts, I said how big my room was and I still got answers like "it might work".. I'm just here to verify it :p... Thanks everyone for your responses! There much appreciated!!! :smoke:
  17. Im going to try the same thing but without the filter... I just put some coffee beans in a cheesecloth to nutralize the smell... i asked some people if they smell anything and they said it nutralized it pretty well..

    but pics of ur set up man! i might want to switch it up to UR set up.... What kinda duct fan? just a home depot fan? i saw they were like 15 bucks which is in my budget
  18. its a 4" induct fan @ 80 cfm.. it was 40$ at home hardware.. I think home depot has them to tho... Just waiting for my seeds and then im going to fully assemble the room and start
  19. hey, first post here on gc... been able to get all my info just by reading others experiences which was great. after numerous hours of searching for such an example (of course i never found this thread), i went with a diy carbon filter and this fan. the "box" i built is 2'x2'x2', with the intent of treating it as a pc grow just with a bit more space. so i mounted the fan on the underside of the top of the box blowing out > diy carbon filter > vented into room. my temps are a bit high (running 150w cfl's for now) so i think i'm going to order/go pick up the can-filter 2600 rather than spend another day building one and hoping it works. going to try it out with that delta fan. just a little info on the delta fans... they make beasts static pressure wise, a lot more powerful than the one i grabbed. they're hard to find as they're discontinued but find the model you like on the above site and just search for it. it's not loud at all mounted inside the box with the filter on top, sounds like a computer on steroids running but nothing a little tv noise can't handle. also, i'm going to try and push through the 2600 like my current setup to save space inside the box. if not, i'll have to try and put the filter inside and pull out. i guess that would be ideal with the pre-filter and all that, ugh.

Share This Page