Please remind me about Vent connector(s) rule of thumb. These pictures are a single wall non B-type for natural gas hot water tank and mid efficiency furnace manifold into a L vent metal chimney flue. Combustible clearances appeared to be about 6 inches. Is it OK to use this single wall vent connector, should it not be a B vent consistently?
Furthermore, I believe this is mid efficiency furnace was manufactured in 1992, can anyone please confirm?