I realize I'm late for this party but feel I needed to add info for similar questions in the future. I've been an HVAC licensed contractor since 1979 and now support 3 equipment manufactures with onsite consulting and training. This is a very common question easily answered. What are your needs? How long will you be in your home? I'll start with the difference in 80% and 95% (condensing) furnaces. With an 80%, every dollar you pay the gas company 20 cents goes up the flue. With 95% only 5 cents goes up the flue. So basically you save 15 cents on every dollar previously spent. Now for single vs. 2 stage. Your home has an average heat loss figured for anywhere in the US. A competent contractor will do a Manual J calculation to determine the load of your home (more on this later). This load will provide enough heat for your average lowest temperatures in your area. But how often do you hit these lowest temperatures. Generally only a few hours a day or a few days every month. Which means you actually burn more gas than you need to and your furnace cuts on and off often (short cycles). Basically it's oversized for most of the winter. With a 2 stage furnace the furnace fires at a lower rate when demand is lower then bumps up too second stage if the demand becomes greater. This creates far more comfort in the home by reducing the hot and cold spots in rooms which are more prevalent when a furnace short cycles. So efficiency (80 or 90+%) reduces your money up the flue and staging reduces your money spent on comfort. Here's a problem I run into often. A contractor sells you a 95% efficient furnace and removes your 80%. After a month or 2 you see your gas bills go up! What happened? Furnaces have an Input and Output (or bonnet) rating. A 100,000 btuh 80% puts out 80,000 btuh. A 100,000 95% puts out 95,000. Some contractors just look at your old furnaces input rating and goes "like for like" rather than a proper Manual J calculation because it's easier. So if you remove your 80% 100,000 btuh furnace for a 95% 100,000 btuh furnace as you can see from the example above you would burn 95,000 - 80,000 = 15,000 btuh's more of gas than you did with your old furnace. Choose a dealer wisely and ask to see the Manual J of your home (also shows cooling needs). Hope this helps....

tigerdunes, Thanks for your input. I posted some incorrect info on option 2. The correct coil should be: CNPHP3117ATA with the 58CVA070-12 Infinity VS gas furnace instead of: CSPHP3017ATA HI-EFF R410A Evaporator coil. Regarding option with with AC instead of a HP, I have this information: 58MVC060 95% VS furnace 24APA524 15 SEER CSPHP2112ATA evap coil inf t'stat $6847 before C&R ($4647 after C&R) So the AC option is about $150-$300 less than the HP options, mainly due to equipment rebates and an additional electric rebate. From a conservative perspective, I'd swing to option 2... but hate to give up that 95% furnace for so little difference in price! The Carrier contractor says he doesn't see any problem with installing the 90+ in the attic, since the line is only 2-3' and goes down an interior wall. I wish the 80% option was significantly cheaper so as to make the conservative choice easier to make. I'll check on the addition of a pleated filter media cabinet, but am not sure I'll be happy with the additional cost. We don't currently have issues with indoor air quality and haven't had issues with the existing blower motor. But maybe the new system is different in that regard? Regarding the heat strips.. are you suggesting getting rid of the gas heat altogether upstairs and just use a heat pump backed up by heat strips?

12" return is almost definitely too large for the basement. I have a 6" return in my basement, and I have actually found it to draw ~200-240 cfm (using a barometer) -- plenty in my case with just a few supply outlets. In your case, I have no way of knowing for sure, but I assume it's piped directly (or near) to the inlet of the furnace blower compartment, in which case there is a lot of pressure and it's sucking in a lot of air and making the basement quite negative (not a good thing). So your basement return in that state may have been drawing close to, if not more than, half of the return air the entire system requires. Is the basement floorplan open to the rest of the home or closed off? If typically closed off, I wouldn't be surprised if the basement door had a tendency to close itself when the system was operating. I suppose putting cardboard over half of the grille is one way to reduce its intake capacity. Your older furnace does not (presumably) have a variable speed blower that will vary its RPM in order to maintain a specific CFM setting. That means that while you are noticing more airflow from the rest of the returns throughout the home, in totality your system is receiving less airflow -- no, not a good thing considering your ductwork is likely undersized to begin with. You have decreased its return capacity. To get the SAME (total) airflow from the rest of the returns throughout the home that were not previously drawing as much air generally requires the system to operate at an increased static; with older PSC type blower motors (non variable-speed), this results in decreased airflow. Hence variable speed motors are often termed "constant CFM" as they can adjust (increase) their speed to maintain a constant airflow (cfm) when subjected to as much as 0.8-1.0" of external static pressure (vs. conventional blowers max. of 0.5", which many duct systems are nowhere close to achieving despite it being the standard "design" figure). You can think of the ESP number as a measure of resistance to airflow, in a sense. The fact that you say the (supply?) ductwork is now much warmer is both concerning and telling. It is unwise for me to say much more than that as I am not there to evaluate your system design and give an accurate assessment of the ductwork design/layout, etc. But it suffices to say, with the info you've provided us, your return ductwork is now more restrictive, which would exacerbate any existing airflow issues. You do say it met the set point without tripping the high limit. Please let us know how the system performs as it gets colder out and the system runs more often in its present state. I would like to ask what made you consider replacing the systems (and proceeding to get 8 proposals) in the first place? Are there functional problems with the existing equipment (besides most likely being oversized) or other comfort issues? By now we have at least established that it is likely the existing equipment is a bit oversized and the existing ductwork is marginal -- but that is (unfortunately) exceedingly common on most residential construction. Are you after more efficiency, better comfort, both? It helps us to help you when we know more about your current system's performance. Lastly, I would not factor online reviews into your decision too much. An air conditioner or furnace is not like most appliances (such as a refrigerator) in that the installation practices and quality can make or break even the best equipment selection. There is a good chance that many (but not all) of the negative reviews you read were due to installation errors. This post was edited by ryanhughes on Fri, Nov 22, 13 at 9:51

I've been reading the fascinating debate above. Can someone in the business help or guide me? i work for a small Italian company that has been designing and building quality wooden windows for over 40 years. i think our prices are good and certainly competitive with what has been quoted above. The $1000000 question for us is whether there would be a market for us in the US. Looking for what the "Made in Italy" can offer, I could suggest our ecological leather lined windows, available in a wide range of colours. Our priority remains the quality of our product, including the question of heat and noise transmission. Any opinions are welcome, thanks