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Thoughts about putting exhaust fan low and outside

Discussion in 'First Time Marijuana Growers' started by lucky1972, Dec 29, 2018.

  1. #1 lucky1972, Dec 29, 2018
    I'll save the long details, but I currently have a small 2*4 closet with a 4" fan and filter with a cheap inline 4" intake fan. The exhaust fan and filter are at the ceiling (inside) taking up space and it does run a little warm. I'm thinking about mounting it outside but due to looks I wanted to run it out the bottom vent and trying to build some sort of box to make quieter. I would then put the intake up top. I know this isn't ideal but it would give more space but I'm wondering if pulling the fan will offset the heat from now being at the bottom. My closet tends to spike around 86+
     
  2. #2 A.Friend.Indeed, Dec 29, 2018
    If you have the carbon filter at the top of the tent with a duct tube running through a bottom duct hole that will be fine.

    Honestly though a 4" inline/carbon filter combo should be powerful enough inside a 2x4 tent to place it anywhere inside the tent, top or bottom and not matter as long as there is proper airflow through the entire tent top to bottom..

    Placement of the carbon filter helps when you have a bigger space and need to direct the airflow from the bottom inlet (open hole, dust screens, even a intake fan if you feel the need) to the top outlet (carbon filter) but in that small of a space the airflow isnt hard to keep going at all, many different types of fans out there..
     
  3. #3 A.Friend.Indeed, Dec 29, 2018
    You just dont want any pockets of unmoved air and humidity
     
  4. #4 A.Friend.Indeed, Dec 29, 2018
    As far as smell the carbon filter will do its job no matter where it is as long as you have airflow.
     
  5. #5 A.Friend.Indeed, Dec 29, 2018
    I have my tent setup ( carbon filter hung at top left inside tent > duct tube > hps hood > duct tube > outside top right port > inline fan hanging on wall > duct tube running through an extra laundry dryer port letting extracted air outside.

    If I ran the duct tube from the hood to outside the tent through a bottom right port it wouldn't make much difference... just dont have any sharp bends in the duct tube
     
  6. #6 Rumpleforeskin, Dec 29, 2018
    I'm sure you know most the basic stuff (like heat rises), but some stuff like unbalanced intake fans are not as obvious. An underpowered or unbalanced intake will cause more restriction than a passive hole of a larger diameter. Most of us don't run intakes for this reason.

    My advice:
    Overpower the hell out of your exhaust fan, then double it.
    After a good light source, spend as much as you can on excellent exhaust components.
    Never buy anything that looks like the fan I posted below:

    upload_2018-12-29_10-28-29.png
    I good quality powerful inline duct blower with a high CFM rating will pay dividends and pay for itself in yield increases. Now days you can find great deals on a quality blower. The design looks like the one I posted below:

    upload_2018-12-29_10-31-33.png

    Typically this type of fan can overcome lots of head pressure (means it can displace and move air through several feet of pipe/ducting). A house fan or a small duct blower like the one I posted at the top of this page can't move air through ducting (even though some are advertised as such).
    I like your idea to move the blower outside the grow room (I do it). I would keep your exhaust hole at the top of the room then ducted it outside the grow to a convenient mounting location (even on the floor if you have to). The longer the ducting, the less air your fan will move. Over kill!
    What ever the diameter of your exhaust, double your intake size. Most will just ad an additional hole.
    Example:
    4" ducting to a powerful 6" or 10" blower would require you to put in two 4" holes at the base of your grow room. Don't install an intake fan. Most will just reduce the overall air flow. I like to install short 90-degree black 4" elbows with pantyhose over the holes.

    Best of luck.
     
    • Agree Agree x 1
    • Informative Informative x 1
  7. #7 A.Friend.Indeed, Dec 29, 2018
    Sorry for spamming.. smoked a super sativa this morning! Haha and finally yes removing anything that generates heat from your tent is great. As long as you dont need that extra heat in your tent
     
  8. #8 lucky1972, Dec 29, 2018
    I've had my set up as carbon filter>short duct>green hydrofarm fan>duct through wall and into my office at the top of my closest (exhaust fan is like the large one in previous post). I then have an inline fan as intake (like the cheap one in previous post). I have vent on wall and short duct through wall with bend then intake fan pulling air in. I've had this setup for a couple years with no real issues but I do get to 86+ degrees and have limited space due to the large exhaust fan up top. I don't want to run ducting through/out the top vent for visual purposes which is why I simply thought about flip flopping them and I can hide and probably quiet the exhaust fan. I have a platinum p600 led which puts off minimal heat and I honestly think my exhaust fan pots off almost as much
     
  9. #9 Rumpleforeskin, Dec 30, 2018
    Anything with a lower CFM value will cause a restriction. I would just leave it passive.
    Having the intake as a cooling fan is possible but not ideal. You will be pressurizing your grow space rather than the ideal negative pressure.
    With all that said, I bet no matter what you do, your results will be good. You seem to care about your setup and are doing the best you can with the parameters given.

    Best of luck
     

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