I wouldn't expect a huge improvement going from R4 to R8. See for example this page and the graph under the "Duct Insulation" section in particular: http://ducts.lbl.gov/distribution.html#insulation For some more discussion on this, see this recent thread: http://www.diychatroom.com/showthread.php?t=22514

Hi Mike, No neither contractor did a load calculation. They both live close to me and claimed that for my house the 5 ton condenser I had was barely adequate. For that reason they recommended two 3 ton. It was also claimed to me that for a 3 ton condenser paired with a 80% AFUE furnace, the furnace size must be either 90,000 or 70,000btu. ??? Also in my house, I find in the summer frequently my upstairs gets hot enough that I would like to run the AC, but the downstairs is still quite comfortable. The reverse is true in the winter. Since I have a 2 story entryway smack in the middle of the house, I think the theory is that at those times I could run the system on the floor that needs it, and just run the fan to circulate the air on the other. The rise of hot and fall of cold air will benefit the other floor. Of course there will be times when both systems will have to run. We do go below freezing at times, and hit some 100 degree days. Does this sound like good reasoning to you? Concerning the Carrier rebates. The Totaline thermostat is apparently made by Carrier. I looked it up on the web and on the bottom of the page it has: copyright Carrier Corporation 2008, so I am hoping that is OK. I will email Carrier directly. Also according to the chart given me by one of the contractors, for the Infinity Systems both the Infinity or EDGE Control thermostats qualify for their $1,000 per system rebate, hence $2,000 for 2. Both contractors have said their combo of Boost 80 furnace and Performance 17 series condenser will qualify for the Fed Rebate of $1,500. Thanks for the tip on the additional 10 year warranty from Carrier. I will look into that. Any thoughts on whose price for the Performance system is more reasonable? Thanks for your help!

I just got a Frigidaire Professional Series 30" gas range - 5 burner with continuous grate - has the rapid boil & simmer burners & center (5th burner) comes with griddle insert. Oven is huge - 5 cu ft - comes with a split rack so if you have big roast or turkey or tall cake or something, you don't have to give up the rest of the oven space. Also - its convection, has a warming drawer & I love the look. I haven't used it yet (as we are still working on the kitchen, but it did get good reviews & I've had good luck with Frigidaire in the past). I believe it was about $1300? I was also considering the GE Cafe, but it was about $1,000 more & didn't seem to have as many good reviews. I'll post the link - go into the pictures to see that split rack I was talking about. I got the one in the pic (with the black top) but Lowe's sells on with a stainless top - exclusive to Lowe's. Here is a link that might be useful: Frigidaire Professional Range

Thanks, everyone, for your comments and suggestions. You guys actually brought up a point that's festered in my head for a while -- what's up with our door clearances? There must be a 1-2" gap under our bedroom doors. I suspect they were undercut to make room for carpeting at one time, but then the carpeting was (thankfully) taken out. I'd love to get a door that significantly reduces the gap, as some of you suggested, but I also remember hearing something to the effect of what handymac was saying -- you need the larger clearance to ensure proper air circulation/house pressure balancing. If there's one thing we absolutely don't want to make worse, it's the HVAC balancing in our house. It's already dreadful. This whole subject opens up a can of worms for me. In fact, I wonder if I should spend a little time over at the HVAC forum... Cheers, Ava