I have been reading this forum for some time now and appreciate the opinions and advice given. I would like to get opinions on which way to go for new construction.

We are designing a new home. We are currently in the design stage, and the time has come to start thinking about HVAC. The house is appx 3000 sq ft, single story in the desert southwest (Phoenix). I have done a manual J and it shows a need for appx 3.7 tons of cooling. The house has two logical zones; bedrooms on one zone and living areas on the other zone, each having appx 50% of the cooling capacity needs. We will start talking to HVAC contractors next week, and I would like to be prepared so I don't waste their time or my time and can better understand what they will tell me.

There appears to be three possible routes to go:

1) Two 2 ton units,
2) A single 4 ton unit
3) A single 4 ton unit with zoning control.

I would like to get some advice and opinions to know if there are any major pros and cons of each alternative. I am assuming a single system would be cheaper, but I have know idea about the reliablity or maintenance issues with zoning control systems.

Thanks in advance

Ray