Negative pressure question

So I have my 8x10 foot shack and i'm having a problem with my ventilation system pulling a vacuum and making it hard to open the entry door. I have an 8 inch can-fan yanking the air out of the top, it runs 24/7. I have a 6inch can pushing air into the room up through two filtered vents in the floor.

Any suggestions on how to break the vacuum so the door will be easier to open? I was thinking a hole with a plug I can pull when I want to open the door. thoughts?

Man, that's a tight shack! To overcome the pressure, you would need a pretty large hole. I think the best bet would be to put a switch or fan speed controller on the 8" and turn it off/down when you need to open the door.

thats a simple thing to fix. i work in a body shop for 25 years as a painter and paintbooths use positive pressure to prevent unfiltered air from entering booth. i adjust pressure by speeding up either by speeding up or lowering fan speeds. so the answer is simply match the cfm of the fans. basically you need identical cfm on in fans as you do out fans. if your intake fan is bigger than out fan you will get possitve pressure which would open your door for you lol. but you would get a big wif when you do. if you have a leak it will smell outside room. if i was you i would be happy with the vacuum it means no exscape for sent. if you put a a filter on the out fan (8") you will lower its cfm some which will lesson vacuum. filters on the out fan is a smart place to put them. good luck

thanks for the replies

np good luck

Normally, you would just make larger passive air holes, but one thing I'm wondering is why you're filtering the air on the way in?

lol yea i was thinking the same thing. i figured it was to keep pollen out. more holes will let stink out. try putting your filter on the 8 exhause, that might just lower it enough to make door easyer to open

I filter with household 3M hepa filters to keep pollen/bugs/dust out, then carbon filtered on the exhaust.

wow. neva hrd for that kind of a problem before.

anyone else want to weigh in?

Equalizing the cfm in/out will fix it. If the door won't push open, try putting a tshirt over your intake and see if it helps any. If it won't pull open put a shirt over your exhaust.

you can adjust you pressure by putting a dimmer switch on the exhaust fan to slow it down. or add another intake fan. you problem is real simple your just pulling air out of the room faster than your putting air in room. if you want nuetal pressure you need equal fans

put an 8 inch blast gate in the door, it will take enough of the pressure off the door to open it.