House inspector says there may be a crack in my furnace combustion chamber and that if there is the furnace will have to be replaced. How does a contractor check if the chamber is cracked. Are there any alternatives to replacing the whole furnace?
It depends on what kind of furnace you have as to how it will be checked for a cracked chamber.
Depending on the age of the furnace there may be a replacement heat exchanger availiable. If you are the one that is going to live there I would upgrade to a more efficient furnace. Make sure the contractor figures out what happened to the old chamber if cracked so it dosn't happen again.