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.

. If you're gonna try to make it "comfortable" at all; you're gonna have to do some insulating for sure. Concrete absorbs / transmits huge quantities of heat. That's walls, and the floor too. Trying to heat it up quickly with no / poor insulation is a losing battle . . it will never be comfy without it. A cold floor can make you feel colder that you really are; and unheated / uninsulated concrete will do that for sure. By definition; cranking it up "on short notice" will require a much bigger heat source than bringing it up to temp over a longer period of time. Concrete; insulated or not; is a HUGE heat sink. Can't change the laws of physics. . . . Bob

If you going to use the SunTouch floor heating then you don"t have to worry about the heights as the SunTouch will be lay over your concrete and you apply the thinset and tile directly over the heating floor. In regards to the room heating, the floor heating is will not heat the room itself but it can add few degree to the room temperature. for more information check this installation instruction from SunTouch Good luck Here is a link that might be useful: SunTouch Installation

I would suggest a Rinnai Energysaver. Probably an EX22 or EX 38. It is a direct vent unit with modulating gas valve and blower. Programmable t-stat is built in. Cool to the touch and QUIET! There are vent extensions available to bet the vent to the outside. I ran one in my basement for 10 yrs. Mine was not a finished basement but many times I would turn it on Fri evening in preparation to spending the weekend in my basement shop. What I found was that like yours I did not have an insulated first floor. The Rinnai would heat the floor and it actually would change the comfort on the first floor due to the basement heat heating the first floor. I have heated my homes with these units since 1991. They are excellent?