Passive intake?

**tonyromo** · 01-19-2009, 12:01 PM

With large carbon filter and 8'' fan what size passive intake hole should I have in an 8x12x8 area? Also if I vent from the side top will it be seen by flir or should I just go with a hole in the hollow floor for both intake and exhaust?? Thanks.

**mannurse801** · 01-19-2009, 12:02 PM

What is the CFM rating of the fan with the filter in place??

**tonyromo** · 01-19-2009, 01:12 PM

It is 590 cfm before the filter so I am thinking it is more than enough? So can you answer the question with that info now?
quote=mannurse801;1941745]What is the CFM rating of the fan with the filter in place??[/quote]

**tonyromo** · 01-19-2009, 01:15 PM

Did you get that ? Why can't I get answers to questions like this, I mean it really is not a stupid question and I see so many replies to questions like what light to use for veg or bloom so thanks.... I mean at least there is some room for a question with my set up not like I am asking what hps stands for.....

**mannurse801** · 01-20-2009, 06:14 AM

Hold your horses bro, I was busy yesterday, and was trying to help, I mean you only gave it 3 minuts for a reply, that's not much...
Anyway, that fan should be fine with a couple small 3inchesx3inches passive intake vents. Your CFM is just below the volume of your room, so you will exchange your air .6 times per minuts it looks like.
If you can, vent into the ceiling. If not an option you can vent through the floor. But you don't vant to vent near your intake, pointless.
Ideally you vent up, and intake from below.

**tonyromo** · 01-20-2009, 07:45 PM

Right on. Try to understand my consternation though. Must ask if you know the answer. If I vent from the top side of an out building will the heat signature be seen? That was why I was thinking through the floor but the outside is sort of covered where the hollow floor comes the the sides. Can easily open some holes but don't want to attract attention to the alteration. I get the idea if I vent to the under and draw back even from 12 feet away? I think?, unless I open the sides completly, then I might be getting back my exhaust. Just worry about heat being seen coming out of the top, side, front, of a shed.?? Sorry if I seem impatient but I think you get it. Lots of good questions on here that don't get answered and lots of noobs that get more attention than they deserve. Not hating just want a real answer.... Thanks for the response.....

Originally Posted by mannurse801

Hold your horses bro, I was busy yesterday, and was trying to help, I mean you only gave it 3 minuts for a reply, that's not much...
Anyway, that fan should be fine with a couple small 3inchesx3inches passive intake vents. Your CFM is just below the volume of your room, so you will exchange your air .6 times per minuts it looks like.
If you can, vent into the ceiling. If not an option you can vent through the floor. But you don't vant to vent near your intake, pointless.
Ideally you vent up, and intake from below.