Maybe I am getting messed up by terminology. I have always assumed that exhaust vents for gas fuel appliances (furances, water heates, etc - in this case a Burnham gas hot water boiler) require a fire stop when they pass through a ceiling (i.e. of a utility room) into the attic space. Though, I am not sure which specific code (IRC) applies.
Back in March, there was a thread in which Jerry Peck said, "The collar *is not* a proper firestop or draftstop - its only purpose is 'purtyness'.

IRC R602.8 says "Fireblocking required .... to form an effective fire barrier between stories... etc" (... around all vents, etc).

There is referance to fireblocking required for chimneys and fireplaces (R1003.19), but does this not apply to gas appliance vents?

M1801.9 refers you back to R602.8.

See picture. There is no collar, or support, or insulation shield, and the clearance is less than the 1" required for type-B exhaust vent. But Jerry's comment confused me. Doesn't is also need a fire stop (Collar) around the exhaust vent where it passes through the ceiling??? Which code reference is the proper one?