Hi all, I just joined this board and I'm looking for answers! We have a proposal to install geothermal at our home in Chicago. The price is way more than we expected due to difficulty in the drilling process. We are in the city, on a typical Chicago city lot (25' wide). The proposal has two 350' wells spaced 13' apart. The unit is a 5 ton unit. Everything I've read says the bore holes need to be 15-20' apart for maximum efficiency. At the price we are looking at, I want to make sure we are getting the maximum efficiency out of the system, the bore spacing is my first head-scratcher. Since the wells are proposed to be so deep, does that diminish the recommended space between the wells? We talked to another geo installer and his opinion was it was not feasible to install geo at our location. Thanks for your help, I hope we can move forward on our install and share my experiences here.