We are building a new multi-story home in CT. HVAC system consists of Hydroair with multiple air handlers each running a seperate zone with their own thermostats.

This is where I'm getting confused. There are 2 situations where our HVAC sub connected a single room to 2 different zones.

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(1) Our central hallway on our main floor.

Our main floor is divided in half by a large entry hall that is double height. One side of the floor is our everyday living space (Kitchen, Family Room). The other side has occasional living space (home offices and a formal living room). Given this, the heat/AC will often be fully on in the 'every day side' and in economy-mode on the other side.

We regarded the central hall as an 'every day' area and thought it would be on the same thermostat. Our HVAC sub actually wanted to put half of the vents on one system and half on the other. His rationale was that it was a large room that would be hard to heat and the two systems cycling at different times would help that. He also said it would help circulate the air around house/ between the systems which also helps.

Still doesn't make any sense to me. If one system is set to turn on whenever temps are below 73, and the other one is off basically off because it is set to 60....putting half the vents in this room connected to the 'off' system seems like it would just be less effective not more.

Am I missing something?

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(2) One of the bedrooms on our 2nd floor.

Similar story.

One of 3 bedrooms on the 2nd floor has one vent connected to the air handler serving the other 2nd floor bedrooms. The other vent is conneted to the air hander serving the attic bedrooms (a zone which will again, be in eco mode most of the time since the attic space will only be used when we have guests).

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Anyone seen this done before? Any situation where this would make sense or should I push to change?

Thanks

Michael