What should be used around appliance vents and metal chimneys?

The appropriate choice for what should be used around appliance vents and metal chimneys is an insulation shield. Insulation shields are critical in these applications because they help to protect surrounding materials from the heat generated by the appliance vents and chimneys. This is especially important in preventing heat transfer to combustible materials that could lead to fire hazards.

Insulation shields work by providing a barrier that maintains safe distances between hot surfaces and nearby insulation or structural elements. They are often made from non-combustible materials designed to withstand high temperatures, ensuring that the integrity of the building's insulation and structure is not compromised.

In contrast, vapor barriers are primarily used to prevent moisture migration into walls and ceilings, which does not address the thermal protection needed around vents and chimneys. Vent pipes are the ducts that allow exhaust gases to escape but do not provide the necessary insulation or protection around them. Fireproofing materials could potentially be useful, but in the context of protecting against heat transfer from vents and chimneys in specific installations, insulation shields are the best fit because they are specifically designed for that purpose.