HVAC Star Practice Exam

Air for combustion must be available in enough quantity to support complete combustion of the gas. If there is adequate air, the flame burns cleanly and the furnace operates safely and efficiently. This air can come from the room if the space is properly ventilated, or from an approved outside air intake that brings outdoor air in, as required by code and the furnace manufacturer. In many older or more open installs, room air suffices; in tight spaces or for sealed/high-efficiency units, the outside air must be supplied directly through a dedicated intake or vent. The main idea is to provide an adequate supply of combustion air, from either the surrounding space or an outside source per code and the equipment’s instructions.