I'm trying to figure out all of the clearance distances requirements and looking for the best place to vent a new direct vent water heater. As you can see by the image, the existing furnace vent termination appears to have been installed too close to the gas regulator vent if I'm reading the clearances correctly, but I'll worry about that later. edit - looks like 3' is the required clearance according to TABLE 503.8THROUGH-THE-WALL VENT TERMINAL CLEARANCE
It looks like the area around the dryer vent is a no-go. The installation manual makes it very clear that dryer exhaust is very bad for the water heater, and appears that code says 3' clearance. If I'm interpreting the clearance guidelines correctly, the easiest place to put the new vent is 12" left of the openable door. This would also leave 12" clearance to the existing furnace vent. Does anyone see a better spot to place this vent?