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Originally Posted by naturall_mystic Note how the fans are conveniently located at the end of the duct line. |
Actually, in the case of the ceiling duct fan, they show it in the middle of the duct.
I don't mean to be a pain in the neck; I'm just curious whether there's a real effect or not. I've been doing HVAC work for a while and, like I said, this is the first I've heard of it.
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Originally Posted by naturall_mystic ... A negative pressure system avoids the potential problem of odor leaks as all air is sucked through the system, including any possible leaks. A negative pressure system also makes the seals on both the grow box door and filter work more efficiently as it sucks them closed rather than blowing them open. A postive pressure system (pushing the air through a grow box and or charcoal filter thereby raising the air pressure to higher than that outside the boxes) has the opposite effect ... |
Now those points I completely agree with! Especially with a grow box situated in an attic, where materials will dry out, get brittle, and so on. The same principle holds for air handlers; you want to make the suction side as short as possible in order to avoid sucking unconditioned, dirty, smelly attic or crawl space air into the system.
Like I said, just caught me by surprise ... not trying to be a pain or anything. In any event, kudos to you and the others for not trying to use a computer fan (duhhh ... why's my box so hot with a three hundred cfm fan? I've got fifty air changes a minute, don't I?
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