Ventilation help (semi advanced?)

Discussion in 'Grow Room Design/Setup' started by WA-grower, Feb 14, 2009.

  1. Hi GC peeps,

    Heres a situation, im hoping someone with a little HVAC experience or some ventilation knowledge might be able to help fix it.

    Situation is: 172cfm vortex fan, hooked to a carbon filter. The fan exhaust heads about 3 feet out of the room, and then joins in a home-made Y piece (made out of 3 sections of 4" exhaust hoses) joining the Y with it is a clothes dryer. They both shoot out the tail end of the Y another 10-15feet and exit the house via the "dryer vent". The fan runs 24x7, but the dryer only runs every so often. Since install, the dryer takes twice as long to dry any clothes. You can occasionally get a bud smell in the laundry room so im guessing some air is making its way back up.

    Is there any way I can fix this so both lines still run out the same hose, and the dryer doesnt take forever to dry? I thought about putting a damper behind the Y on the dryer side, but that would only stop air from coming in when the dryer is not running, so I dont know that it would fix the drying issue. Im guessing its some kind of pressure issue since it use to work fine but maybe now that there is more air running down the tube the dryers blower has to compete to get out?

    any insight would be great!
  2. Dampers on both, spring loaded on the dryer side, electronic on the GR side.

    Unfortunately that is all 4" ductwork i presume, and making 2 4" units exhaust out the same 4" pipe at the same time is not going to work. You need to upgrade the exhaust coming out of the house to a minimal 6", so you have a 4x4x6 Y, in order for this to work better than it is. The dampers will help alot.

    Why are we running the fan 24/7?
  3. Yes, all 4" ducting. I could get 6" for the bottom side of the Y, and see how that works. Is there a reason not to run the fan 24x7? If I run it 24x7 I would think id need only the dryer side damper. Would it be easier to just buy another section of 4" and put the Y right where the ducting exits the house so that they only spill together at the end?
  4. Also what if I got a 4" in-line duct blower at the end of the Y to help move things along? For the situation in mind I think it would be the 'easiest' fix.
  5. #5 Don Piano, Feb 15, 2009
    Last edited by a moderator: Feb 15, 2009
    It may help. Give it a shot (the 4" fan). Not too expensive. If you do, maybe get a nice one ( an inline vortex style ) and not a homedepot special, and the chances of it working out for you are better. But i would still get a damper for the dryer side. It is too bad that dryer ducting i not standard 6".
    If you are using a carbon filter, why a bud smell in the laundry room?

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