I have two Comfort Aire furnaces (forced air) located in the basement underneath the family room. My issue is when they kick on you feel and hear the vibrations through the floor. Is this normal?? Can it be stopped or minimized?

Yes, the furnaces can be isolated from the ductwork by flexible connectors so, if there is vibration (and there really shouldn't be any when the fan blades are clean and in the right pressure ductwork) it wouldn't transmit to the ceiling above.

www.heatpro.us energy businessmen's knowledge

Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.