Preformed furnace safety check. Cycled system. Checked and removed burners. All burners are extremely rusted and corroded. Major blockage from burners due to the damage. Checked and cleaned flame sensor. Ok. Igniter is showing signs of being worn. Checked heat exchanger with camera. Found all chambers are extremely rusted and corroded. Found crack in far right chamber. This is an automatic fail for safety inspection. This may cause CO to be vented into the home and is a safety issue. This should be corrected immediately for safety issues. Black-Haak heating not responsible for any issues if system started up by homeowner. Second opinion set for noon today. Nothing collected pending results of second opinion. Job complete.