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.

The $3346 difference between option 2 & 3 is primarily for the desuperheater - thatÂs a lot of money! System #1 SEER equivalent is 24 compared to TraneÂs 15.75. System #2 equivalent SEER is 26.5 vs. TraneÂs 15.75. They have to offer you at least a 1-year warranty (5-years on the compressor). So, what I would do is negotiate a better price for the system (#3) with the desuperheater and a fixed period of say, 3~4 months (say till spring) to decide on an extended warranty. If the system is trouble free all winter, chances are you donÂt need the extended warranty. Bottom line is if you can install a geothermal system for less than $20k  itÂs a no brainer! Last piece of advice; insist on the Waterfurnace with the highest COP (5). BTW: R-22 is at least 5% more efficient in heating mode & closer to 10% more efficient in cooling mode than R-410a from what IÂve seen, but donÂt let that sway you. Go for 2-speed compressor & ECM variable speed blower. IMO SR

I guess you are out in the boonies with no nat gas. I can't help with equipment. It is a relatively low volume kind of demand for equipment, I'm sure. You may be forced into the industrial/commercial area and if you are not big enough, you may be out of luck. Assuming that you can get a suitably sized unit, if your hydronic system is designed to deliver heat with a low enough water temperature, it can probably be done efficiently. What is the water temperature currently set to? Try heatinghelp.com and terrylove.com. I've seen some good hydronic heat/boiler threads in both places. If you have to stick with an electric boiler, you might look at the installation of a large storage tank and going to day/night rates. You'd have to run some numbers to see if it will work for you.

There is something terribly wrong with your description of what the house will be vs the heating load of 9-10 tons. A "ton" of heating or cooling load is 12,000 BTU/hr. The house you describe is not what you'd call "huge" anyway, at just 3300 sq ft main plus another 900 over the garage. Finally, such a high heat load clearly is inconsistent with any house that is "superinsulated." As others have pointed out, you need to have someone competent do a detailed heat loss calculation for the house, using all details of construction, U values and sizes of all windows and doors, and anything else that affects heat loss. Most HVAC contractors either don't know how to a really good calculation or won't take the time to do it, relying instead on rules of thumb. For comparison, my superinsulated house in central NH (climate zone 6), finished in 2011, has a footprint of about 2000 sqft, with two levels, for a total gross square footage of about 4000 sqft, close to what you propose, but with a different configuration of course. It is heated by GSHP (standing column well design). The regional distributor of the unit installed and two of their "approved installers" all came in with around 4.5 tons of heat load, which they proposed satisfying with a 5-ton unit, even though I had given them all details of the house and my own spreadsheet showing a heat loss of somewhat less than two tons. In the end, I bought the two-ton unit. The tables for the unit showed that at the air and water flows to be used, it would deliver over 25,000 BTU/hr of heat in second stage, or about 75% of that in just first stage. As it turned out, the unit keeps the house at 70 F throughout the winter, in just first stage. My best calculation of heat load when it's 0 F outside is about 19,000 BTU/hr, somewhat better than my last run of the spreadsheet prediction. In summer, cooling mode provides AC; the unit is really loafing then, as the cooling load, worst case, is less than one ton. Your first money ought to go toward making the shell of the house truly "superinsulated." There is a wealth of information on how to achieve this, but still relatively few builders with experience beyond building house just "to code." I followed the subject of building science and superinsulation over a span of about 30 years, leading to my specifying the construction of my own house. I found a local builder interested in doing something new and different, and we worked well together. I didn't tell him how to frame, and he followed the design and my input on air sealing and other details. The house has a double exterior wall frame, typical of a great many superinsulated houses. The outer wall is 2x6, inner 2x4, with a 3" gap between. The insulation cavity is 12" thick, filled with dense pack cellulose. Windows are a mixture of triple pane casement and fixed glass. The foundation walls have 2" of rigid foam inside, another 2" outside. If I had to do it all over, I'd just put it all on the inside, as I had to cover that with 2x4s flat-wise and sheetrock over that for thermal and ignition protection, as required by code. The lower level slab is poured over a 4" layer of foam. The house is air-sealed to a high degree of tightness; the final blower door test came in at about 0.8 ACH50, vs Energy Star requiring 3.0 or better. Fresh air for human health and to keep interior humidity from getting too high in winter is provided by an HRV (heat recovery ventilator). The incremental cost of making your new house truly superinsulated class isn't all that much. I'd give serious thought to skipping all that expensive radiant floor heating. As someone else pointed out, in a highly insulated house the floor surface temperature won't get warm enough for it to feel warm underfoot. That wouldn't happen until the floor got into the upper 70s, and with little place for the heat to go the whole house would warm up to close that temperature, which most people would find stifling. Save the plumbing cost of radiant floor heating, and put it into the building shell and windows. Do your reading, get someone competent to design the shell and do a really good heat loss calculation, and you likely will not exceed the capacity of a three-ton unit. One final thought - give careful thought to isolating the living space over the garage. Such rooms typically are hard to heat and leak too much air from the garage, something you really don't want.