Well, I understand that it is a 20 ton unit made in 1993, anyway.
I could not follow most of the rest of the posts.
It is working well, and like I said, it is pretty quiet. It is getting old though, so I am wondering in how many years I need to plan to replace it.
I certainly understand the disadvantages of reheat, but it has been hard to figure out how, in this building, to retrofit to something else.
Thanks, everyone, for all the help.