Thank you for your response! I'll try to answer your question below define poorly installed batts. We have gaps between bats AND some sections where batts don't lie flat on the attic floor. Builder's insulation subcontractor originally tried taking the 9inch thick batts and slicing them in thirds (like slicing bread) to make three 3 inch batts that he thought I would accepts as the correct insulation! These were laid between joists. When I caught onto the subterfuge, he claimed that he hadn't been aware of the cheating but would make sure the insulation was done over properly. Instead, he allowed them to just drape 9 inch batts perpendicularly across the joists over the top of the 3 inch thick slices. Because it was very difficult for me to get up into the attic (attic ladder hadn't yet been installed), I trusted builder to make sure it was done over correctly. It wasn't and it is a MAJOR mess. To the extent that we are able to reach the batts, we intend to pick them up and reposition them correctly or just take them out. But there are areas behind the heaters that the only way to reach is by crawling over the heaters so we were hoping we could just blow insulation into those areas without first repositioning (or taking out) the batts. Guess not. do you have service platforms around the units? there should be a 3' walkway to and around units for service. The units both lay beside a platform so it is easy enough to get to one side but there is no walkway "around" them. check & see if batts were installed under unit platforms and walkways...water heaters too if they are in the attic. there are batts between the joists that the units sit on. Whether the batts extend the entire distance under the units were only put in place at the very edges to make it look like underneath the units was insulated, I honestly don't know. Will have to pull a couple out to check. Thanks for suggestion. understand that under heating system you'll only have R-30, which is code here in La. how about in Tx? at max we put R-38. We're outside of a code restricted area but under our contract the builder was supposed to have built to meet code requirements of the nearest major metro area which, at that time was R-30 in the attic. New recommendations for this area are R-50. I'm not sure what the nearest metro code now requires. I don't know what value you plan to insulate to... what is your goal? and what is the purpose of the added insulation? We would like to get as close to R-50 as possible even if some parts of the roof are only insulated to R-30 or lower. Seems like it is good to insulate as much of the attic as possible to R-50 to reduce heat transfer between attic and living areas. I find it is usually air leakage into the house that people try to solve by adding insulation. it never works unless the new insulation both insulates and air seals. (foam ins) with propane you'd have to add combustion air if you foamed the roofline. many insulation companies don't understand how to do this...nor to hvac companies. air sealing is easier with batts than with any other insulation. move the batt...do the air sealing... put the batt back. Not sure I totally understand you here. Our attic is not sealed. We have ridgeline vents and soffit vents. So far I haven't seen any signs of inadequate ventilation in the attic and I know that we need to leave space for air to circulate between soffit vents and ridge vent. We intend to be sure to leave the baffles in place and not block either end. As for air infiltration into the house, the house is pretty tightly sealed. We fired the builder before the interior walls were insulated or sheetrocked and I personally went around with cans of spray foam filling in every crack where I could see light coming thru the exterior shell. All the gaps around exterior electrical plugs, etc. Then we hired a different insulation sub to install the wall batts and I checked every piece of it before sheetrocking started. So, the house is tight. do you have recessed lights? IC or ICAT? the IC lights are a big leakage to living space. We do have recessed lights. They are ICAT. (I've checked). were ducts mastic sealed? or just duct/foil tape? returns in attic mastic sealed? I don't know. What should I look for to find out? And if just duct/foil tape sealed, what is the proper way to fix it and is this a job a homeowner can do or will we need to hire pros? I'm assuming this should probably be done before blowing in additional insulation so one is not having to tromp over and thru the blown in insulation to reach the ducts to work on them.

I don't understand the concept of why the low stage can't be used in a dual fuel situation. Let's say is 20 degrees outside and it is more efficient to heat with the gas furnace than the heat pump. The Infinity furnace will use its low stage to try the maintain the set point in the house. It is going to cycle on and off to try to maintain the house at 70 degrees. This is what it does in my house. The Carrier Infinity 58MVB060 has two stages and cost about $200 less than than the three stage 58MVC060. However the 58MVB has a high and low stage, and no middle stage. So in effect you still have a furnace with a low stage. I am not an expert when it comes to installing in an attic. I would be worried about condensation freezing. All I can suggest is you voice the concern to the contractor and have him explain to you how he will deal with it. I suppose he could use an electric heat strip to keep the condensate drain warm, but again I assume he knows what he is doing.

energy_rater_la: they quoted 5" of open cell foam (~R20-value) for an area of ~800SF (floor dimensions are 28x27 w/ 4.5' attic height (hip roof). the upstairs rooms of the fourth level (side by side split) does not share attic space. stickman42: that's definitely my concern and am going to stick with 2 systems. the ductwork cost is just too high mike_home: there is ductwork in the unconditioned space. 1 thinly wrapped metal duct, 4 sets of R-4 flexible duct. 2 companies have now said to remove the old insulation b/c otherwise they feel it would trap moisture/humidity in the attic. I'm struggling with this one myself as it doesn't seem necessary esp. given the additional expense. And I am now working on finalizing the quote for a Lennox 96% AFUE furnace. The blower motor is currently rigged to run 24x7 until I can get unit replaced hopefully soon. This will at least get my system back while I determine if I should do the spray foam. Thanks for your input.

I would avoid putting the HVAC system in a closet. The best place for northern areas is the basement. I'm in the extreme south (Katy, Tx a suburb of Houston) and I tell people all the time with closet installed systems that they should consider moving it to the attic. (there are no basements here) The reason why the attic is "usually" the better place here is in most cases there is more room to access and repair the equipment. Don't put a system in thinking it will last forever. They all break at some point, the easier it is for service / replacement the better. I would also avoid "furdown" units or in the wall systems, thru the wall etc. These are mostly apartment style units and can be quite challenging to work on. I pretty much view them as "disposable" air conditioners. - When they break, buy a new one.