First, forgive me for being such a novice, but I am hoping to get some help regarding setting up a multi-zone HVAC system.
Currently my house has a Dual Zone split between the upstairs and downstairs but I am trying to add two additional zones. The upstairs is about 1,000 sq ft and the system seems to work fine in that area, the downstairs however is impossible to properly heat or cool. The downstairs is about 2,700sq ft and for an easy description is divided into a north section (bedrooms) about 800sq ft a middle section (kitchen/living) about 1,000 sq ft and a south section (master bed/bath) about 900 sq ft, currently the air return and downstairs thermostat are in the south section.
Issue: Because of the way the system was designed it seems impossible to heat or cool the downstairs to a comfortable temperature for everyone. During the winter the North section becomes an freezer, the middle is somewhat cool and the south is an appropriate temperature, however if we adjust the thermostat to heat the North section of the house the other two rooms become to hot, during the summer the opposite situation occurs.
Plan: we would like to be able to divide the downstairs into 3 zones, I have been reading about numerous systems that are designed to do just this, however when talking to an HVAC professional they said it was not possible because residential systems are not built to be split because of back pressure.
Any help, feedback or ideas would be greatly appreciated.