Watch this video to be informed by Jeff Lee of how to avoid a furnance scam.
Having cracks in the furnance heat exchanger is very dangerous but finding the cracks is a very difficult thing to do.
If a technician has told you they have found a crack in the heat exchanger, you should be able to see it also. Some companies will claim that you have a crack in the heat exchanger when you really do not in order to make more money.
Therefore it is wise to choose a company with a video camera inspection system which is able to travel up inside the recesses of the heat exchanger to find any bad or cracked portions. This way you will be able to see the cracks yourself on the LCD monitor.
Be cautious and know the facts to continue to keep yourself and your family safe.