I don't know anything about returns and where they should be ideally. I am adding a forced air system to a 1914 house. All contractos have the same plan for supplies. The are going to run from the basement all the way to the 2nd floor and hit each room from the attic with insulated flex. On the main level they are going to run a main trucnk perpindicular to the joist and take off from the top in the joist spaces and put floor registers where they are needed.
Now when it comes to returns they don't seem to concerned, witch bothers me. Where is the best place for the returns? One contractors plan was to put the ruturns in the ceiling on the second level and floor on the first just like the supplies. Another tried playing me for dumb and said it didn't really matter and was just going to put one off the trunk on the main level and another off the trunk on the second level and that would be fine.
Where will a good contractor tell me the ducts should go on a retrofit?