©2013 Green Building Advisor. From The Taunton Press, Inc., publisher of Fine Homebuilding Magazine.
I'm trying to make a decision on which type unit to go with. House is approximately 1665 sq foot ranch with equivalent walkout (daylight basement). See plan here: http://houseplans.co/house-plans/1236/ 
We got rid of the small crawl space and opted to make full basement. Everything caulk and sealed, 2x6 walls w/owens corning propink r23 insulation. r50 blown in fiber in attic. r5 externally insulated basement in conjunction with r5 eps insulated interior (rim joists included). The basement slab is insulated as well. The house is located in (zone 4) Shelbyville, Kentucky. I have multiple geo quotes and air source heat pump quotes. Got decision down to two quotes. First is for a 3 ton single stage 5 series waterfurnace geothermal unit w/desuperheater and 40 gallon preheat tank; and a heat recovery ventilator. There are three 185 foot vertical ground loops. The unit also has intellistart, axb controls, and touch screen thermostat (consequence of the 1500 rebate deal) Initial istall would be $24132; would end up costing $15800 after rebate and 30% tax incentive. The quote for air source heat pump would be 4 ton 16 seer rheem 2 stage heat pump and a heat recovery ventilator. The price for this unit installed w/duct work would be $11500. Which option would you choose and why? Thanks.