need advise on ventilation

[drambouie]

i have a 3" 50 cfm exhaust fan sucking hot air out the top of grow room and a 4" tube from the attic bringing cool air to the bottom of room for circulation, i was hoping the fan would **** hot air out the top and negative pressure caused by the fan would **** cool air from the tube. it seems to just **** all the warm air from my house (verry little from the tube) and lower my temps in the house. the room isnt sealed, do i just need to add another fan to blow air into the tube from the attick or **** it from the attick?

 

[drambouie]

**** = su*k

 

[bloodred]

well from what you've described it seems that sealing the grow space is the first place to start, especially since you dont have a fan blowing air in from your attic intake, I know there's a way of multiplying the square feet of your grow space to know how big of a fan you need also, but not sure of exactly how it calulated, i'm sure you can find out on here somewhere. That whould be another thing to consider.

You might think of putting one on each end (intake and exaust) after figureing the amount of cfm you need, seal the space and make sure your exaust fan is taking out more than your intake is pushing in. What i did was put a smoke down by the crack of the door before sealing it and if it takes the smoke in you know you got negitve pressure. I'm far from being an expert on this but these are things i've been doing and having great results, good luck.

 

[Greenfinger]

here is a guide for indoor light to extractor matching...
that is if the file fits on here...lol.....
sorry fokes just seen how bad that image really is
have sorted my scanner now ...lol....------
...so a simple diagram may help......too much beer