I purchased a 96 year old, 2 storey home. The heat venting runs right through the kitchen and needs to be moved about three feet over. How is this done? I intend to hire a contractor to do it, but want to go in with as much knowledge as possible.

Usually the pipe is just moved or extended from its present location BUT an exact description is impossible without being there to see all that would be involved.

Round ductwork? Rectangle? Flexible? Have someone out to give you an estimate, ask them what they would do and how they would do it. If it makes sense to you and you think you could do it give it a try.

A 96 year old house probably was built with no cenbtral heat so this is likely an add-on. Since you will be hiring a contractor he will know how to asnwer your question and do the work. Someone long before him already did it once.