Goodman Furnace Burner Orifice, #45 B4089345 Genuine OEM. This is a Genuine OEM Goodman part. This burner orifice (part number B4089345) is for furnaces. Burner orifice B4089345 regulates the flow of gas coming from the gas burner valve. Wait until the surface is cool to the touch before installing this par... - Goodman Furnace Burner Orifice, #45 B4089345 Genuine OEM.