Where are you located, how do you currently heat the house, and what are the approximately sizes of the three zones. Is this a three story house with a zone for each floor? Would all the air handlers be installed in the attic?

Before we discuss prices we should see if the proposed equipment is appropriate.

I don't understand how a dealer can call a 13 SEER low end Carrier condenser a high eff model...since this is a mismatched system of different brands, just wondering if there is an AHRI rated system match?....what is warranty of the components? I assume you have an existing boiler for hot water?

IMO

Connecticut, and there is hydro air. By using First Co air handler they can just swap the existing one without redoing the pipes, also it's less expensive because I need a hot water coil if I go with the Carrier matched handler. They also told me the Carrier air handler is larger so would be harder to fit. I have an oil burner and indirect water heater. Also each zone is about 1500 square feet, and yes one zone per floor, second and third floor air handlers are installed in the third floor.

Warranty is 5 years for air handler, 10 years for Carrier compressor, and 1 year parts and labor for the entire system. Thanks!

One more question, I am also thinking about the 17 SEER Performance two-stage outside compressor for better efficiency, but heard there are some issues with that unit. Should I stick to the 16 SEER or go for two-stage 17 SEER?

Hydro air systems are not very common. I have no experience with them and they are rarely discussed on this forum.

How much do you spend annually on fuel oil for heating and domestic hot water? I imagine it is a lot of money.

Have you considered abandoning the hydro air and installing a heat pump in it's place? The installation costs should be comparable in either case, but I would think you would save money on heating costs and you could get a matched system with a 10 year parts warranty.

It think a 2 ton AC for 1500 sq feet on the third floor seems a bit undersized. Was the old AC able to keep up on a hot day?

SEER ratings are for a matched system of condenser, coil, and air handler. If go with the First Company hydro air handler and the Carrier condenser, you will have a mismatched system. That means the SEER rating is unknown. If you spend the extra money on the 2-stage condenser it will be more efficient but you won't know by how much.

The 2-stage condenser is great for controlling humidity. But be aware that in a 2-ton condenser, the low and high stages are about 1.3 and 2 tons. It is not until you get to the 3 and 4 ton sizes that the differences are more noticeable. It is something to think about.

Heat pumps won't work because it's way too cold in the winter, no? I spend around $4,000 a year on oil and around $3500 a year on electricity.

The second floor unit would be a 3-ton, and the third floor would be a 2-ton. The new quote is around $19,000 for matched system, 16 SEER performance for third floor, 17 SEER two-stage Performance for second floor. Seems a bit high?

You are spending a lot of money on oil. Is natural gas available on your street? If it is then you could be saving a lot of money if you could replace your oil boiler with one fueled by gas.

The performance of the heat pump drops as the temperature goes down. Therefore the heat pump needs a supplemental heat source. The most common is electric heat strips. You may be able to use your hydro system as the supplemental source. This is commonly referred to as a dual fuel system. The control becomes more complicated than what you have today, but I think it could be done.

I agree $19,000 is a lot of money, and it doesn't solve your $4000 a year oil bill. That has to be a better solution.

Well the hydro option is probably only made by first company if I had to guess.

The hydro thing is a specialized thing and small market so a major manufacturer typically isn't going to get involved in that. So you're left to choose what manufacturer does these things.

Some times your options are few and this may be the case here.

2 stage AC when installed properly isn't any more troublesome than a single speed. These are best suited for humid climates (year round).

For a 2 ton system as already stated this is probably over kill for what you really need, especially if humidity is of no real concern most of the year.

"Heat pumps won't work because it's way too cold in the winter, no"

Maybe, "No," Depending on energy costs and equipment efficiencies/COPs, you may be able to avoid oil usage down to something below 25 degrees. (25 degrees F is the cost crossover point for my (YMMV) dual fuel (Oil and Heat pump) set up.)

I have neighbors in similar homes to mine that spend thousands of dollars per year on heating oil. I spent $237.90 for the last two years. The difference is I have a heat pump and oil and they have an A/C and oil.

Where in CT?

But aren't you spending much more in electric then?

Yes your electric bill increase, but your oil bill would decrease. For every dollar you spend on electricity you may save 2-3 dollars on fuel oil.

What Mike Said!

My winter time electric usage cost (heating) went up slightly, but I also installed a Hybrid Hot Water Heater which more than offset that increase.

A few folks that have been providing help here for years can help you "do the math" to compare the fuel costs for a heat pump vs oil. Post your full electric rate, oil cost per gallon, equipment, etc and nicely ask for the help. :-)

If you have an electric hot water, also take a look at replacing it with a Hybrid hot water heater.