Is a two story 6000 sq foot house? Are you including the basement in the 6000 sq feet?

The furnace you listed is 40K BTU, and the AC condenser is 2.5 tons. Are there multiple systems? If not then you have under sized equipment in my opinion.

I have two separate HVAC systems in my 2-story 2700 sq ft house and wouldn't have it any other way. In a 6000 sq ft house, multiples are the only way to go.

Assuming you are going to have 3 of those systems for your 6,000 sq ft, I would forego the Infinity system but definitely get 2 stage outdoor condensing AC units (they are only available in 2 or 3 ton sizes so get a good load calculation done to make an informed decision which size to get)..

The recommendation from our HVAC contractor was the following:

Basement+first floor:

3.5 ton carrier A/C 16 SEER 24ACC642

Carrier furnace 95% 59sc5a080

Install matchingg 3.5 ton Carrier Coil

2 zones sheet metal

Aprilaire Wi-Fi thermostats and Auto damper control

Honeywell 4" filter rack

Top floor( Bedrooms)

Install Carrier 3.0 ton 16SEER 24acc636

Install Carrier 95% furnace #59sc5A080

INstall martching 3.0 ton Carrier Coil

One zone sheet metal

AprilAire Wifi thermostats

Honeywell 4" filter rack

1) Does this seem reasonable?

2) Would it be worth upgrading to infinity for the top or bottom two floor

• Quoting $2744 to upgrade to infinity( 24AB736 and 59Tn6A080+infinity thermostats+ smart sensor+ damper control board)
• Addtl $2025 to add Aprilaire ducted dehumidifier and $840 for #800 Aprilaire steam humidifier

3) Would it be worth upgrading to infinity 2-speed on top floor( Bedrooms) for $ 8684 ?

• upgrade to infinity 2 speed

• 1 zone sheet metal + infinity controls

• 17SEER 24 AB736 2 stage

• Carrier 2 stage variable speed Infinity Furnace #59TN6A080

• Infinity wi-fi thermostat

• Infinity Smart Sensor

• Infinity Damper control

• Thanks in advance

What is the size of the first and second floors? Will the basement be mostly underground? Will both systems be installed in the basement?

The first thing you should be discussing with your HVAC contractor is a load calculation. The calculation determines the sizes of the furnaces and AC condensers. I don't think a newly construction house of your size should require 6.5 - 7 tons or cooling, or 160K BTU of heating. If your contractor does not want to do a load calculation then find another one.

Once the sizes are determined, then you can decide on zoning. I recommend the first floor and the basement be zoned especially if the basement will be finished as living space. I highly recommend not installing any equipment or duct work in the attic for house of this size.

If you are going to get Carrier equipment then I suggest getting the Performance series at a minimum. The Infinity equipment is very nice but it can be expensive. I think spending the money on 2-stage AC condensers and variable speed furnaces are worth it. If you get the Infinity equipment then you don't need to spend money on a dehumidifier. New tight construction should not need a humidifier. You may need an HRV ventilation system.