1.I would want to see a load calculation in writing for each zone. I question the sizing especially on the furnaces. 2. Keep in mind basements at or even partially below grade have a very low heating and cooling load 3.assuming you have no installation issues with outside venting, I would get a price on Carrier's 58MVC high eff furnace for the main floor/basement zone. 4.as far as heat pumps, you would need an analysis of your electric and at gas rates. 5. If you have humidity issues in the basement, you need to address the issue of why before trying to solve with dehumidifiers. 6. Dealer should address your temperature issue with the master bedroom with insulation check and ductwork size check. I will assume room is the opposite in the winter heating season. Windows are high quality? 7. I always prefer new and correctly sized refrigerant linesets. IMO

garyg: These are the figures that led me to switch my buying preference from an Infinity 19 to a 16. The second ARI reference is for the Infinity 19. One would think that because one is a "19" and the other a "16" that the SEER for the 19 would be a lot higher. But it's actually 0.1 lower, at 14.4 compared with 14.5. I wonder how many people are mistakenly thinking they are buying a much more efficient unit than they really are (especially with the 5-ton units). I think the industry ought to require manufacturers to make their literature clearer in this respect, instead of referring to unattainable figures (or ones that are only achievable with a certain furnace and HP or AC tonnage). So given no real advantage to the Infinity 19 over the Infinity 16 that I can tell with my configuration, I'm going to choose the lower-priced Infinity 16 (a little lower EER but higher cooling capacity).

Thank you for the prompt reviews! Looks like Proposal #1 is the winner so far. Mike ��" the attic fan made a huge difference in second floor comfort. One of the best things I did. Glad your experience was the same. I will look into the 2 stage AC. I will not run the fan or put in an extra return for the humidity/temperature change issues. I will just continue to use my dehumidifiers. They do take care of the issue. I am going to plan on replacing the line set ��" it is easy to get to. What do you think about the drain pan/wet switch that will shut off the AC if there is a leak? Is it going to go off over nothing like a smoke detector I used to have and drive me nuts? Or is it a good idea? I might not have been clear about one thing. Both contractors told me to keep the old air filter set up (Spaceguard High Efficiency). It is the old Aprilaire humidifier that Contractor #1 said replace due to age/parts and Contractor #2 said keep it, parts are not going to be a problem and the only part that goes bad is the solenoid. Keep the old one or buy a new one? Contractor #1 is going to look into the Carrier early failure of heat exchangers settlement. It might only apply to the secondary heat exchanger. The primary one failed on my furnace. I meet with the last contractor tomorrow. I hope to have all the bids by the end of the week. My goal is all new equipment before I have to turn on the heat!

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