I'm thoroughly confused about venting options for propane stoves. I understand direct vent, and I understand the concept behind B vent. What I'm confused about, however, is whether B vent for gas/propane requires an exterior chimney that goes above the roof line. Most of the stuff I've seen on the internet is vague about this but seem to hint at it. Other sources - like the images below [from Regency's website] - indicate that the B vent would be a vertical run inside with horizontal vent to the outside.