Sounds like you want to hold-off any construction so try this: How are the basement windows? Most are single pane. Install some of the plastic window shield over them (the stuff you shrink with a hair dryer). Run the circulating fan from the furnace continually. This will keep the basement near the house temperature while refreshing the air there. Possibly add another heat vent - duct it over a window or to an outside wall. Our basement is finished with 2" XPS insulation against the concrete. It too drops to the low 60's but doing the above raises the temperature. We installed an electric fireplace as auxulary heat to make the space more comfortable in the spring/fall when the furnace is not running to heat the house. I don't believe there is a "good, inexpensive" solution. Water heaters are not efficient or intended for use as a boiler. Good luck.

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 basement can not exchange heat quickly enough compared to a ground loop. It will get very hot down there in the summer and freeze everything solid in the winter. Open loop systems will have maintenance problems, corrosion or scaling, that closed loop systems do not unless the water quality is perfect. The rates of water withdraw and injection might be problematic. (What is the pumping rate of a typical residential well vs. what you need for a heat pump?) You might have environmental permit issues with "waste" water injection into the ground water.

If it were only so easy… Consult with a local professional experienced in commercial in-floor radiant design and installation. The building code in Alberta for in-slab radiant might include 4-inch foam insulation between the concrete and the ground. To prevent freezing, the circulating fluid should be a glycol antifreeze mixture. For efficiency and use of a low temperature liquid, close-spacing of the loops should be included in the design. “Easily” is a loaded question, as is ‘working’ and ‘working properly’. Don’t look for shortcuts, there’s a lot that goes into a ‘simple’, well designed system with many parts that all have to work together, be installed in the right sequence with the right spacing and being of the right size. With Hydronics - everything matters - Done right, you’ll love it! IMPO SR