In my never ending quest to get my Garn installed, I am now to the point of going through the wall with my intake and exhaust pipes.  I have been okayed to convert my garage into a Garn den.  This will cause me to build a garage next year that is unattached to the house.  The problem that I have run into is one of placement.  The Garn's (1500) exhaust must remain 12" above the intake pipe if it is going straight out and blowing downward into a sand filled container that manages cinders.  My question is how critical is it that the intake be offset from the exhaust?  Would it be a problem to have them both come out of the wall with the intake directly below the exhaust pipe?  The problem is that I have a natural stone wainscot on the the outside of my house.  I have taken out a floor to ceiling window for the exhaust, but the intake would have to go directly through the stone.  I would like to flush mount the intake 12" directly below the exhaust, keeping in mind that the exhaust continues out another 24 to 30 inches.  Any thoughts?

Robert