So I have had three HVAC guys look at my place so far and the first two said they couldn't vent a 90% furnace but the third guy said he could do it.
Left and right sides of my building are really not an option as there are buildings almost directly next to me. In the rear I have a deck and beyond the deck is another condo. 10 or 11 feet above my deck is another deck which belongs to my upstairs neighbor.
SO the HVAC company wants to vent from the house just below my deck and then put PVC through my deck so that pipe runs from a couple feet below my deck to a foot above it. Then he wants to turn it 45 degrees upward and vent out. So basically my exhaust will be on my rear wall and ten feet below my upstairs neighbors deck.