Hello Forum. I'm buying a new house. The house is about 100 years old, and has the traditional radiators for heating, and no A/C. The house is about 4000 Sqf on two main floors, a finished basement, and a third floor suite. I want to install a highly efficient heating and cooling system. In my current house I had this done last year. I installed a traditional duct system with two zones. It works great, but all the ducts take up quite a bit of space. Now I'm thinking that maybe I should install the high velocity system instead since this require less space for ducts. For me the most important thing is that I get the best and most energy efficient system out there. What should I chose? What are the pros and cons with the different systems?