HELP with understairs

Hello. i am growing in an undertsairs cupboard i dont know the measurements but is a normal understairs space in the shame of an L.

ok it also has a door on it


a little similar to that, but its taller the door frame is made from metal, anyways im having, a little trouble figuring out how to create a negative pressure with out having to cut into my door or walls.

I am going to be getting a 5' carbon filter from ebay, im going to be funning the silver hose outside of my door on my growroom, so the door is going to be open, i could drill a few holes in the bottem left of the wall were the brown lines are on the pic below, into the cupbord, and leave the exhaust fan there. i need help just creating and understanding negative pressure.



sorry about the longish post and looking forward to the replys thank you very much.

anybody.....??????????

bump bump bump

if your room is current a sealed space, say you've 4 bare walls
you likely going to need to cut some kind of exit hole
to create a draw of air, you need somewhere to vent the air, that flow of air will create a negative pressure in your space which will feed the outflowing air

In your grow room you'll need some sort of inlet, and an outlet. The inlet can just be the crack under the door, you have to have someplace for the fresh air to 'come from' and some where for it to go. If you don't care about looks (basement) or whatever, i'd run your dryer hose to your boiler vent. If you are just using the crack at the bottom of the door for an intake, I'd cut a hole in the wall towards the ceiling at the highest point and run that over to the boiler's exhaust. That along with a normal oscillating fan inside the room for interior circulation, and that will keep your room nice and vented. Put the 5" (or is it really 5'?) carbon filter in the dryer hose, then hook the hose up to your fan so that your fan is in/on the wall blowing air into the hose with the filter in it. The boiler vent will take whatever smell you have left up to the top of your house and into the air where the chance of someone pinpointing where it is coming from is almost impossible. Plus, the constant heat from the boiler even when it isn't running will be enough to lift all smells up and out of your house. As long as the intake is slightly less efficient as the exhaust, you'll have a negative pressure in the room. and no smells or air can go anywhere but out your exhaust.

*One tip i would offer is to caulk the piss out of the underside of your stairs, try to get it air tight.