"1.HVAC guy B tells me this is not a great idea as my Lennox furnace lacks the variable speed fan that is the key to getting the designed benefit out of the Carrier Infinity." a variable speed fan with infinity control provides better humidity control by reducing airflow to increase comfort. ````````````````````````````````````````````````````````` "2. HVAC guy B recommends that while I am replacing the system (A/C and Heat) for the upstairs area that I relocate the new unit from the basement to the attic. Guy B says this would eliminate approximately 20 linear feet of uphill ducting to get to the trunk line and improve the overall efficiency of heating and cooling upstairs." air follows the path of least resistance. if your source (furnace) is closer to your destination (your upstairs rooms) your system will perform better. 20 feet of ducting between your furnace and registers is a pretty good distance. your air will probably lose velocity by the time it reaches your upstairs. ````````````````````````````````````````````````````` "A. HVAC guy A says pumping refrig uphill causes accelerated failure of the system...yes, no maybe?" this is simply not true. if the lines are sized properly to allow for proper velocity and oil return you shouldnt have a problem. ``````````````````````````````````````````````````````````` "B. HVAC guy A and B both recommend using an 80% furnace in the attic vice a 90% furnace, which they recommend for the basement. Why not put a 90% in the attic? Is it because of the amount of water a 90% produces as a by product of combustion...and water in the attic is not a good thing?" heat rises. makes better sense if youre using a 90% and an 80% to put the higher efficiency furnace downstairs (where theres more heat loss) when some heat from the 90 is going to rise upstairs (where theres more heat gain).

campbell I vote for the Carrier Infinity system as long as it includes the Infinity controller. The two spd AC condenser is a plus over the sgl spd Lennox. I assume cooling is more important than heating. I would look at load calculations very close and get the smallest Infinity furnace that has a 4 ton rated blower. Ask your dealer about this. IMO

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

nearly 4 grand for an 80% furnace? atleast you got the fancy infinity controller. I'm assumining they linked that up with your a/c so you can control humidity. Atleast you received the nice filter's. For that kinda of money you could have gotten a 95% furnace installed with the control and new filter cabinets for probably a little cheaper. Thats just my opinion though. Ofcourse the 'bigger' shops aren't cheap. Smaller independent new companies and independent installers usualy give the best prices on installs.