I recently had my house undergo an inspection in process of a sale.
The only thing that the inspector pointed out was that the gas line from my furnace to the water heater in utility closet was copper. That was not standard practice now days and should be looked into.
We do have an old house with a 19 year furnace. I plan on calling a licensed plumbing and heating company but wanted some feedback as to in today's setup what is the material of the pipe that should be used.