I would be concerned with pathogens that are under your house. Is this a mobile home, or is the 'crawlspace' actually a shallow cellar with concrete floor and walls?
Bringing in outside air is a good way to introduce pests and disease if it is not filtered correctly. Usually, the air within your house is preferable, as it is at the correct temperature already, and as a bonus, has elevated levels of CO2 from the human inhabitants...
stinkyattic Reviewed by stinkyattic on . ? about venting from crawlspace to attic If a person wanted to set up a 4' X 5' flowering room, using a 1000W HPS (w/ cooltube) would they be able to bring in "fresh" air from underneath the house, from the 2ft crawlspace, through the cool tube, and up to the attic? The reason I ask is b/c the air under most houses is kinda stale, but it is very cool, just wondering if you start moving the air if it would start becoming more "fresh". There is also concern with a little bit of moisture from under there, which they are trying to get Rating: 5