Air source heat pumps don't make sense in areas where winter temps frequently fall below 32 degrees. Once you get below freezing, you will be running the auxillary heat a lot. If you decide to go the air source route, you will want a second stage gas fired auxillary heat. I live in the mid-atlantic region in the mountains and selected GT. That choice was coupled with a blown cellulose insulation package. My other choice was a propane heat/electric AC with a foam insulation package. Both options were roughly the same install cost. Both would have provided similar energy efficiency. At the time we selected, propane was 3.75 a gallon and rising (with no end in sight) so we went with GT. The delta cost for the GT system (above the cost for a HE propane heat and electric AC system) was $15,000 for the heat pumps and loop plumbing (including pumps) plus $17,000 for digging the pit. The pit excavation should not have cost as much as it did but it is a 12 ton system and the hole was gigantic (120' x 48' x 6'). We live on a mountain and hit a bunch of boulders that required special equipment to get out. Rocky soil also required a 1' base of stone dust to cover the loop piping. The total cost for the GT HVAC system including all ducting was $50,000 plus the pit excavation cost of 17K. It is a large investment and I would only recommend it if you plan to live in the house a very long time. My heating bills are great - maybe 300 dollars maximum a month during peak winter for an 8500 square foot home (5900 living and the rest a condiitoned but unfinished basement). Make sure that whatever equipment you choose can be maintained by more than 1 very qualified HVAC company who has many years of GT experience. In my area there is only 1 GT company who has over 20 years of experience but I am stuck with them for maintenance. There have been times when I wanted to fire them but cannot. Local competition is a good thing. Also - if you build a tight home make sure that you consider ventilation and dehumidification in the HVAC design. I wound up adding both a whole house dehumidifier and energy recovery vent after we moved in becuase we had basement moisture issues as well as stale air in the winter. Tight homes are great for energy efficiency but can create health issues too. It is easy to deal with as long as you plan for it. Good luck with the build.

OMG, reading this makes me so glad that I don't have ducts in my crawlspace anymore. Here are some of my previously-posted thoughts. I wish I had more time to edit it. I hope it is at least marginally understandable. ------- A couple of things to keep in mind that are often left out by marketers and sellers. Most mini spits don't have back-up heat so you will not have any heat while they are defrosting. (I think I ran across at least one brand that does.) So far, the only time I find it annoying is in the morning when I want things to be warming up fastest. Otherwise, I don't really notice it. I know that with Mitsubishi's current residential equipment, the 1:1 systems have better low temp performance than the multi-splits. They are more efficient too. Even if they do have back-up heat, you can kill the efficiency pretty fast if you need back-up very often. Keep in mind that there are alternatives to the wall-hung indoor units. They cost more, but there are units that can be dropped into ceilings and others that sit on the floor. There are also short, ducted units that would solve that big room problem by splitting the supply and return. Condensate needs to be dealt with using pumps. I have 7 of the old-fashioned wall units. The only place I would change in my house is the dining room. It is a small room and it is obtrusive there. I should have used a ceiling cassette in there. They do cost more and are less efficient. What mini splits might not work well for is conditioning a bathroom. For that you might need one of the short ducted units to handle one room and a bathroom. Unfortunately, that will add a lot of cost. Ceiling cassettes or small air handlers might have been less expensive to install than wall units despite the equipment cost in a couple of rooms. I thought of this when my system installation was well underway, unfortunately. The reason might be unique to my house. Since we were abandoning a duct that ran through a chase in the middle of the house, and the condensate lines that also ran through the chase, we could have very easily routed the refrigeration lines, drain lines and control/power cables through that chase for several rooms rather than going through walls and under the house. It would have required condensate pumps, but that is a relatively minor issue. This kind of thing is where installer experience is likely to be a factor. Installing a mini-split through outside walls, as is it usually promoted, is pretty quick and straightforward (Read fast and cheap straight through the exterior walls.) compared to installing a new duct system in an existing house with no central AC. My install was done through interior walls running the lines/cables under the raised house and out to the side which was much more complicated. If I were doing this over and I had a good duct system within a house envelope, I might stick with it to save money. The trouble is, what is a good duct system? More often than not, they are outside of the living space in older homes. In addition, they are considered good when they leak 5% of the air and they only get worse as they age. Even if the whole duct system is within the envelope, you will still get pressure differentials that can force air in or out of the house. Summary of the factors that went into my decision: I had a crappy duct system. My system was in the attic with parts of the duct system in the attic and a trunk that was a furred-down space over the main hallway. That space was both in and out of the conditioned space. The worst part was one duct that started at the AH in the attic, dropped down under the house in a chase and ran for about 30 feet before it reached the first floor register in an addition with a flat roof (thus no attic). It then reduced in size and ran another 25 feet under the house. That part might have been mini-splitted even if the rest of the house retained a ducted system. Mini split sellers market their good dehumidification heavily. The variable-speed-blowers and variable speed compressors would help with low-load situations better and single-speed equipment. I am sure that some variable-speed ducted systems can match it. In my climate, if you have a lot of air infiltration, you will have a humidity problem no matter what you install. No matter how good at dehumidification any cooling system is, in my climate (US, Gulf of Mexico coast) a dehumidifier is a very nice thing to have for a few weeks out of every year. If you go mini splits, don't mount a wall unit above where you will have a bed. I saw advertising that showed that and planned that. I changed my mind figuring that at low speed, at night the cold air would sort of cascade down over the heads and be uncomfortable. I am glad that I changed my mind about it. I don't know if that cooling-mode problem would occur. What I did find, since we did the installation during heating season, is that the default programming of the heat pump mode makes the units good ceiling heaters. As they approach the set point the blower speed goes way down so hot air gets stratified near the ceiling even though the louvers are pointed down. Setting the blower speed manually to a slightly higher speed fixed that. A ceiling paddle fan would too. Putting the indoor units above the bed would have been uncomfortable if only for that reason, hot air right in the face. As far as efficiency goes, my worst of my three "systems" is supposed to operate at SEER 17.5, and HSPF 8.9. The 1:1 systems are rated better, some over SEER 20. Obviously, I do not have to subtract duct losses from that. I appreciate the ability to put ducts within the house envelope, but you can still get pressure differentials from room to room that push air out and suck it into the house. My house is a 1940 raised, wood-frame house that probably could have been built in 1920 for the construction techniques. It must have been conservative builder. It is notable that the house still has all the doors and walls that it ever did. (I have none of that open floor plan nonsense. If I am going to stay married, I need to be able to get away from my wife sometimes and she needs doors to slam when she gets mad at me.) We only seriously heat or cool rooms that we will be in. We are not home much either, and we are working in the kitchen a lot when home. The life style has a lot to do with our decision. Minisplits are inherently zoned and our house lay-out is such that we can take advantage of that. I have found the remote controls of the Mitsubishi not very flexible. You can set on and off times, but you can not really make true setbacks. You might want to check the possibility of hard-wired controls and investigate closely how the remotes work for several brands. One thing you might want to keep in mind. As of 2011, I can say that the Mitsu (and perhaps all brand) multis are less efficient than the 1:1 units and they do not do as well as the single units with heating at low temperatures. For the former, I think it stems from the fact that the compressors only throttle back to a certain percentage of max. For example, a single unit might be rated at 9000 BTU. If you only need a little cooling, and assume that they throttle back to 10%, you can efficiently get 900 btu out of them running constantly with no on/off. If a tri unit is probably 22,000 btu and can throttle back to 2200 btu with the same assumption so your compressor will be flicking on and off more often which yields poorer humidity control and not as even cooling as you might expect from looking at data from the single units. This might affect planning an install of a system. If you are going to have one single unit in addition to several multis, you might consider putting the single where it will be operating at low load a lot, like a bedroom. I have some interesting data in some service manuals that I was able to download that shows, a little indirectly, what the lowest capacity is that they will run at.

You should definitely be pricing with just heat pump. I live in NC which probably is a bit colder in the winter. We get down to the teens but only 15 nights a year maybe. Our winter average low is about 30. Under 10 degrees is definitely a news story. I have 5000 sq ft. I'm looking at my NG bill of $30. I have dual fuel and seer 16 heat pumps. Last winter was very cold and I spent about $700 with $200 being gas. This winter is going to be $120 in gas. My electric rates are similar to yours without the first 1000 discount. What is my point? Your gas usage will likely be $100 a year. Even if that were replaced with all heating strips, you'd be saving $200 a year or so. Since it would probable be 80% heat pump still, the dual fuel is only saving you $40 a year. So a $2500 furnace to save $40 a year seems a little crazy (on dollars alone). Turns out for me, it is probably worth it but only marginally so. I have a 90% (which you should be able to do as mine is basement with horizontal PVC exhaust). It probably saves $60-$70 on an average year. Probably cost $2000 (new house - I can't remember). What is that a 30 year payback (or never if you count interest or NG rates increase)? You do get some flexibility and you can setback at will with dual fuel. That is worth something.

Based on the information you've provided, sounds like the York quote is the best option, but I don't agree with the 80% modulating furnace. That's a high-end furnace, and going with the 80% version doesn't make sense to me, especially in our region where it can get cold at times (I'm in Maryland). Is PVC venting an issue? The York Affinity is a nice line of equipment. American Standard isn't bad, either, but the equipment that the York rep. is quoting is better in my opinion. 3 tons is a bit much for your cooling load, but it's what you'd have to go with if you went with the Affinity line. The 2.5-ton Latitude unit would be the better fit. With the low stage on the Affinity approximately meeting the cooling load at design conditions (which won't be met on all days), I don't think you'll be getting those long run times that you should with a 2-stage system. Ask the York rep. if he can quote the CZB or YZB 2.5-ton single-stage Affinity unit with a 90+ efficient v/s furnace (modulating or 2-stage). Not sure where the American Standard rep. came up with his sizing. Do you like it cold in your house (68-70)? Did the York rep. do the load calculation?