We always have to keep in mind that we are using todays NG prices which are argumentably unusually low to make decisions reaching far into the future. Understanding where the cost of exploration is, and adding an ROI for the investments of gas companies puts a different price on NG.

Our area is blessed with both cheap NG nd cheap KWH electric rates. Even with tax credits we need other contributors such as a need for new furnace and air conditioner to re-coup customer's additional investment in energy savings in less than 10 years. If we are buying geo on a stricly energy savings ROI exceeding 10 years begins to make other places more attractive to put your money.
There are places where geo doesn't make economic sense. Anyone here will tell you. That's why a lot of research is important before making the geo "plunge".

Yes NG is not available in my area. Only propane. The cost per galon is greater than going to the gas station down the street and exchanging a grill tank. On top of that there is an annual rental fee, fill fee, mileage fee, and all sorts of other extortion. The only way I would consider it would be if I had a gen that ran on it.

After last nights cold and snow I noticed my air source units stayed on almost all night. I dont think it is practical at this point to think the second floor will help the addition. I am again considering a third 2 ton unit for the second floor of the additon. This will be probably the most efficent approach. I like this idea better than zoning and installing a bigger second story unit. Less duct work and completely independent controlls. Afterall, that section of the house is completely outside of the current housing envelope. Once insulated it will still have insulation between it and the rest of the house.

I found a rather lengthy thread about some guy's open loop system which dumps the water used in the heatpump back into the same vertical well that it came from. This seems to be pretty common when I read further. I was not originally interested in open loop because I was afraid the pump and dump approach would deplete my well faster than it would recharge (sorry cant keep track of the technical term.) In my case I would simply install a loop field on the discharge side of the pump. The loop could allow some of the gained or lossed heat to be equilized by the ground prior to putting the water back into the well. That way I will not have problems with the well being too warm in the summer or cold in the winter.

My current well is a shallow well and the waterline starts at about 35 feet. The casing is 3 feet wide. While doing construction the builders hit the pump wire and pulled the pump out to test their theory that the breaker was bad and not that they hit the wire. They dropped the pump back down and it was only about 3-6 inches in the water. Even at that depth it took filling the washer 4 times, the dishwasher running, and some showers to bring the waterlevel down enough to effect pressure. After the water was off for about 5 minutes the water line rose back up and we were good. I took me 2 months and a local water shortage before I even realized that the thing was not deep enough and the extra hose curled up in the casing was normally stretched all the way out. I plan to get a total water depth soon.

Also, something to note current outdoor temp is 30 deg f. I let the sink run a while to make sure I was pulling in well water and the tap water measured 52 deg f. Very nice temp for geothermal from what I understand. Edit - I just took a shower, filled the washer, and ran the sink for a few. Tested again and the water temp is now 56 deg f and the outdoor temp is still dropping. Seems that the water in the tank under the house and in the pipe coming from the well cools slightly after being pumped up. 56 is even better.