We currently have copper pipes that feed the propane to our house and are converting to natural gas. Do we have to change the piping that we currently have? Thanks a bunch.
RJ Melton :)

Depends on where you are at? Here it is illegal to use copper for natural gas.

You will also need to UPSIZE the pipe. Natural gas usually takes a 1/2 inch black iron pipe size MINIMUM for furnace operation.

Any company in the business of selling natural gas will have all this information for you since it is required by the AGA and other laws. It is also included in the installers manual for the furnace and your local building department who will inspect the work will also have the info you need.