We are replacing a 24 HVAC system in a house built in 1991. Living area is 2,600 square feet on two floors. We live in Western Massachusetts and thus have very cold, snowy winters and relatively hot, humid summers. I'm hoping that I can get some thoughts on the pricing offered on this system. (I will appreciate any thoughts that you have as I always find the folks at GardenWeb know their business!)

We have decided on a Carrier system for both heating and AC. There are quite a few dealers that service Carrier in our area, but only two do installations. That means there is competition, but not on a grand scale by any means. Both installation firms are highly regarded on Angie's List and other review sites that I've found.

The better quote of the two includes the following:

1- Carrier 59MN7A080V21-20 97.4% Variable speed gas furnace

1-Carrier 24VNA936A003 18-19 SEER Air conditioner

1- CNPV03621ALA Coil w/txv

1- Carrier Infinity controller (Wi-Fi Capable)

Carrier zone system with second floor remote sensor

Labor

Gas permit

Removal of old equipment

Sales tax

Some additional information on the quote: Both the gas furnace and AC are from the Infinity line. The furnace is their top-of-the-line Greenspeed Intelligence model at 80K BTU. The AC is a 3-ton, 5-stage unit.

Price for the above is $17,700. This includes splitting our home into two zones (first floor, second floor) from its current one-zone set up. While it will take some added equipment and expansion of some ducts, the main ducts carrying air to and from the second floor are already in place and won't need to be changed. Cost to do the same system not split into two zones would be $15,500.

We are having some duct work done in the basement. All of the branching ducts feeding the registers downstairs were originally installed with flex duct that was too small and not proper for this system. The charge for this will be another $2,500, but that is independent of the system that we ultimately select. This price also includes extending one of the main air trunks to be a bit longer to make the branching ducts in that area shorter.

The Carrier filter system that uses pleated box filters is included with this system and will be big step up from our current use of 1" slide-in filters. If any of you have experience with other Carrier filtration options (ERV, UV, air purification), I'd love to know what you think (and what you paid).

I have one other question about the quote that I'd like to throw out there. This installer provided quotes for three levels of systems (Best, Better, Good). The duct work noted above is independent of each level of system. Here are the prices for the three levels of systems:

Best (Infinity)

Price with Zoning: $17,700

Price w/o Zoning: $15,500

Zoning Cost: $2,200

Better (Performance)

Price with Zoning: $14,400

Price w/o Zoning: $12,700

Zoning Cost: $1,700

Good (Comfort)

Price with Zoning: $11,200

Price w/o Zoning: $10,100

Zoning Cost: $1,100

My question is this. Why is the zoning cost different for each system category? Is it really double the cost to zone a top-of-the-line Infinity system versus a third-tier Comfort series system?

Again, I'll gladly take any information that you want to share. I'm especially hopeful to get some guidance on pricing. Thank you very much in advance for your time and knowledge. I'll put some equipment URL links below:

http://www.carrier.com/homecomfort/en/us/products/gas-furnaces/59mn7/

http://www.carrier.com/homecomfort/en/us/products/air-conditioners/24vna9/

http://www.carrier.com/homecomfort/en/us/products/evaporator-coils/cnpvp/