Well I think both of you hard heads are partially correct Scott with his 2 story one system properly installed and balanced. Trouble being most are not installed correctly and never balanced to many contractors install the minimum amout of return and none upstairs they want to use the stair well as the return and it does not work, leaves hot and or cold areas.
In my 40 years of HVAC work and 21 years as a inspector I agree with David the best way to heat and cool a 2 story is with two systems and in my area I am seeing more and more 2 story’s with two system and I am talking about forced air systems
Agreed Charlie. Very few duct systems designed properly.
Tough to get it right with structure, plumbing and other things to work around. Then bidding against someone willing to do the job for material and wages…
Thanks for the information, viewpoints, etc from both you and David.