Rick,
First, a question:
WTF
is that other termination?
I see the wind turbine, and the (what looks like) gas vent, but the other hooded four side top thingy (technical term) ...
Also having difficulty following your inside the attic photo.
- The exterior orientation of the wind turbine and the other 'thingy' is such that the 'thingy' is higher up the roof than the turbine, however, based on the photo ... is the photo showing the end of the OSB left hanging and unsupported, or is that a real nice and clean saw cut?
- Assuming that the further away 2x is the rafter, and the closer (lower) 2x is a purlin, then it makes sense and the 'thingy' is higher up the roof, but ...
- The 'thingy' is supplied with what looks like Type B Gas Vent - and the exterior photo does not show a Type B Gas Vent Cap on it.
Regarding your question, though, not sure if there is any minimum clearance between the two.
The 3 feet (above) only applies to "forced air inlets":
- G2427.6.7 (503.6.7) Forced air inlets.
Gas vents shall terminate not less than 3 feet (914 mm) above any forced air inlet located within 10 feet (3048 mm).