We bought an american std high-efficiency furnace a couple of years ago. Every winter it stops working at some point due to buildup of hoar frost on the inside of the cold air inlet pipe. We've had technicians come out to look at this and they've said that the intake and outlet are positioned backwards - that the hot/moist air should not be exiting down below because it rises and then the moist air freezes on the cold air intake as it is being recycled into the furnace.
The office at the company who we bought from disagrees each time with the tech and says the vent install is correct. (Of course that doesn't change the fact that every winter hoar frost blocks the intake pipe, so basically we don't have a reliable working furnace.)
It would make sense to me, assuming that the total distance and bends in the pipes permit, to raise the hot exhaust significantly and also to raise the cold inlet (but lower than the hot exit), since without the hot air exiting below, blockage due to snow buildup would become a concern. But, perhaps there's some reason this wouldn't work or be permitted due to codes? I don't know. At any rate, I'm anxious to figure out some sort of resolution to the symptom, whether the theory as to the cause is correct or not.
I've attached a photograph of the actual pipes as they exit from our home, annotated as to which is the hot out and which is the cold in.
Can anyone offer any advice as to what needs to be done to fix our hoar frost problem?