If it was practical, I would fire the builder.

Of course you can't. But how can a homeowner make an informed decision without hard facts? You can't.

I suggest you have a serious heart to heart sit down talk with your builder, not over the phone but face to face.

Until then, you are totally in the dark as are the forum pros who can't provide informed advice.

One obvious conclusion. You are looking at more than one system.

BTW, what s your location?

Good Luck
IMO

Thanks so much Tiger!

My location is Hickory, NC.

I have hire him yet.

Be aware that most builders know very little when it comes to HVAC. They also tend to budget the least amount of money possible and tend to outsource the job to the lowest bidder. Don't be surprised when you get a blank stare when you ask about details on the HVAC system.