I am wondering if it is prefered to run a straight through-the-wall vent pipe at 2 feet length or can 3 feet of straight length be used? I ask this because it seems like 3 feet of horizontal run is the maximun. But I think there are times when someone might not want the pellet stove backed right up to a wall, so you could get behind it for cleaning or to get to an electrical outlet, etc. Also, on the exterior of the house would you want about a foot away from certain types of siding? Like white vinyl for instance- so it doesnt get smoke soot on it? The 3 foot length would allow for extra clearance for these situations.