Abstract: A combustion air kit for providing a source of external air to feed a fire in a firebox is installed during new construction or as a retrofit unit into existing fireplaces. A masonry air vent brick having a hole therein air flow is included in the combustion air kit. The flow of air through the brick and to the firebox is regulated by a spinner cap mounted for rotation on a threaded post seated within a plug contained in the air vent brick. The air vent brick is connected to a flexible duct which is attached at an opposite end to a vent inlet brick located on the external of the house, chimney or other structure. The vent inlet also includes a vent inlet cover to provide an attractive inlet for the air to the firebox.