Originally Posted by
Eric Barker
Ted, There is quite a bit of info that supports the incorporation of the crawl space into the conditioned area and I strongly support that. We have a great deal of humidity here in the summer and when it enters a cool crawl it can create significant problems. Perhaps in other areas of the country it's not so much an issue.
Back to pulling combustion air from the crawl: You can do this with an attic provided that the attic itself is well ventilated. Crawl spaces on the other hand will often have vents to the exterior that can be closed. Not that I would necessarily expect this to actually make much of a difference, but by the book, it's a consideration to make note of.
My big concern is that I have seen more than likely an 80 20 reason in most crawls for not drawing air from there. The 80 being the bad conditions, moisture mostly, smell, rodents, insects, plumbing or should I say sewer gas leaks and so on. I have not met to many folks in my life that ever go into their crawl to check for concerns until something shows up because it is so obvious they know something is going on down there. In a world of proper maintenance to a crawl space (that does not exist) I would have no problems with drawing air from a crawl.
As far as closing ventilation from the outside to the crawl. In a world of proper maintenance to a crawl (that does not exist) I would not have a problem with that either.