Here are my install instructions. The vent kit I can purchase from the manufacturer would give me a normal rain cap to use horizontally. And your telling me that a rain cap will not mount to b-vent. Only single wall vent pipe?
I'm going to be doing an install this week almost identical. The one question I can't seem to answer is. How does rain water stay out of the rain cap? My heater instructions tell me I need to pitch the b vent toward the heater. Meaning any water that gets into the cap will drain directly...