Master Plumber Practice Exam 2025 – Complete Prep Guide

A single-wall metal pipe must terminate at or above the draft hood outlet or flue collar to ensure proper venting and prevent backdrafting of combustion gases. The draft hood is designed to mix exhaust gases with air, allowing for the safe dispersal of those gases into the atmosphere. Terminating the pipe at this point creates a reliable pathway for exhaust to exit and maintains the proper pressure within the venting system, which is crucial for the safe operation of appliances connected to it.

Choosing this termination height also addresses safety concerns, as it helps prevent the buildup of harmful gases, such as carbon monoxide, which can pose serious health risks if allowed to accumulate indoors. Additionally, adhering to this guideline helps maintain regulatory compliance, as local building codes often specify minimum termination heights based on the type of appliance and the configuration of the venting system.

The other options involve conditions or components that may not adequately ensure proper venting or may not meet code requirements, making them less suitable choices for the termination of single-wall metal piping.