Single wall vent connector

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?

model# 395CAV042075
serial# 4192A21025

Much appreciated!

Single wall is typically used from the furnace to the chimney pipe (B-vent) which is used up through the home and out. Single wall clearance is 6" to combustibles.


Looks to me like picture #4 shows singlewall elbow into B’vent is closer than 6" to wood…?
I’d also recommend sealing previous screw holes and joints. Minimal concern probably, but technically accurate to call.
Is that R/A grill installed on ductwork, plenums, etc…?

Greg, your right it is a little less than 6". That grille you see is a supply grille on the supply plenum.