What size and efficiency furnace and AC do you have now?

How has existing HVAC performed both heating and cooling? Be specific if any problems.

You certainly do not need a Greenspeed heat pump if you have nat gas service to your home.

If you are concerned about correct sizing, insist upon load calculation to be certain.

Throw the GreenSpeed dealer overboard. He is talking nonsense.

Post back with info.

IMO

Wow, these two contractors are giving you a lot of bad information.

The fact that you live in the New York area (I'm in central NJ), I am confident you have a high electricity rates. It makes no sense to an expensive heat pump like the Carrier Greenspeed when you have access to natural gas. This can be confirmed if you post your rates for natural gas and electricity.

The sizes these guys are quoting seem very oversized. Too big is as bad as too small. You need to find a contractor who will do an accurate load calculation.

The Carrier Infinity (Bryant Evolution) is very nice equipment if it is sized and installed correctly. My suggestion is to get a 95%+ efficiency furnace with AC. The contractor should verify the duct work is properly sized.

In my opinion it is not worth paying to upgrade to a heat pump in the NY area.

Have to agree with everything Mike says.

You need a load calc to determine size, both for heating and cooling.

I do like Carrier Infinity furnace paired with either Sgl stage Performance 15 AC or two stage Performance 17, of course with both media cabinet and the ubiquitous Infinity controller. On condenser, I would think no more than a 3 ton.

IMO

Thanks to your feedback. Unfortunately, none of the installers performed any load calcs. I even called another Carrier authorized dealer, but he was in/out in 15 min so am not expecting to receive any calcs with his proposal.
I assume its not something I can perform myself.
Given that my current system is 2.5 tons, I assume that the current ductwork is not sized appropriately for either the 3.5 or 4 ton system.
Although my current system is 2.5 tons, my den was an on and it's 250 sq ft with high ceilings. The room is not getting enough heat currently (the air flow into the room was poor). Both installers agreed that we need to expand the ductwork to get the room heated/cooled properly.
Given the price differential between green speed and the normal infinity furnace system, I didn't mind paying a little more for efficiency. However, if its going to end up costing me more because both the heat pump and furnace end up turning on most of winter, then it's not worth the upgrade.
So difficult to find a proper installer willing to do the due diligence necessary up front these days!
Mike- my electricity rates are 21c/kWh while my gas rates are 1.47 per therm or 1.52 per ccf
Thanks for all your help

What area do you live in and who are your utility providers? I can believe your electricity rate, but your gas rate doesn't seem to be right. Take out the service charge when calculating the rate. It you don't it inflates the numbers.

You can do your own calculation for $49 using HVAC-Calc. I have never used it myself, but I have read it is not difficult to use and approximates the Manual J calculation well. It will give you a good indication.

If you do get a dual fuel system (furnace and heat pump) then I feel the Greenspeed is overkill. Carrier has the Infinity and Performance heat pumps which have good performance and a quite a bit less in money. You want a high efficiency furnace no matter which path you take.

It looks like the problems in the den need to addressed. This is independent of what equipment you buy.

Keep looking for contractors. If you run out of Carrier dealers, then try a Bryant dealer. Bryant is the same equipment as Carrier and sometimes a little less money. You are going to spend quite a bit of money so you want to do this right.

Here is a link that might be useful: HVAC Calc

Thanks again Mike. I included my delivery charge as part of my gas rate. It was .55 per ccf for the supply and an additional .65 per ccf for delivery (live in Westchester).
I will look for additional dealers and appreciate your input. My dealer did tell me that if I get the heat pump, I can go down a model on the furnace, but still recommended a high efficiency one.
Regards