Sorry for the long first post, but I am quickly becoming passionate about Geo. (Also am an engineer, in another discipline, and geeking about this Geo stuff is just too cool) I live in Colorado SE of Denver (@ alt=6000ft) and have a 4000sqft home (2K ranch with a 2K basement with minimal walkout exposure). Built in 1993, with AC originally, good attic insulation, 6-inch exterior walls, and very good double pane windows (by 1993 standards). Current heat is nat. gas @ 125Kbtu and a 2.5 ton AC unit. I want away from my gouging Nat Gas provider in the worst way possible. (charging up to 4X price for Nat gas). One neighbor switched to propane and is saving a bundle!! Go figure. House is on 5 acres, but ground is too dry and sandy here to do horizontal at any reasonable depth/length. Load calcs put me between 5 and 6 ton for heat. Cooling is less than 1/2 the heating need (Colorado does have an up side). I used a contractor finder service to get 4 companies for estimates on a Geo system, but only got three. The 3 estimates are as follows: Contractor-1 $72,000 Was basically a bait & switch. He tried to sell me on a lower cost yet very expensive replacement gas furnace instead of Geo. He's out. Contractor-2 $26,000 Inside: 6-Ton Climate Master HTV60A1 with 10KW backup strip and minimal return air modification to existing ducts; Includes hot water system. (System design for 0-deg heat day and 95-deg cool, standard for the area) Outside: 5 - 200' bores @ 3/4" with bentonite grouting (TC .88), 20% methanol solution. (split bid between 2 contractors, inside & outside) References: Contractor has reference in same area with a slightly smaller home but more above ground running a 6-ton/5-bore and has had no problems in 2 years. Other references offered. Contractor-3 $40,000 Inside: 5-ton Century (he claims it is made by climate master), 10KW heat strip, and complete duct system rebuild; Includes hot water system. (System also designed for 0-deg heat day and 95-deg cool, standard for the area) Outside: The same 5 -200' bores from contractor-2 (uses same driller) bentonite grout, 20% methanol solution. References: None offered (haven't asked) I'm leaning towards working with Contractor-2, as they were the most open about their design process and don't seem to be trying to sell me something I don't seem to need. (Down side is they provided a split bid between the driller/loop guy and the HVAC guy) Questions: Do these bids seem normal or are they out of line? It seems like it is better to go just bigger with the HE instead of just smaller. Are there any problems with this theory when the calcs are close? Short loop seems to be the number one problem discussed on this board. Does it make sense to ask for one more 200' bore to go along with that 6-ton unit? Is it common to have a split bid, or should I insist on the "one throat to choke" model in case there are problems? What kind of performance guarantees are truly reasonable to ask for without having a reputable contractor walk away? I am hearing that efficiency rules and design is everything, so should I be steering my contractors towards any particular HE manufacturer or be setting a minimum set of COP and EER numbers for their design? Again, what is reasonable here? Is there a set number of places that I should be asking for as far as monitoring ports installed, even if I am not running a monitor to start with?