First off, thanks to the site for being a wealth of information for someone like me shopping for geothermal systems. I've been having a heck of a time getting call backs in my area, so I only have been able to get one quote so I would really appreciate feedback. We are taking advantage of the impending death of our central A/C unit to make the jump to geo. At the same time, we're investing in a community solar project (our panels, their farm, remote net metering) with the goal of going Net Zero. Contractor: A large home performance/HVAC company. Their website has several case studies on geothermal systems they've installed in my area. Inputs: 46 kbtu heat loss, 22 kbtu heat gain System: 1 - 500' vertical loop with 1-1/2" pipe GeoStar Sycamore 5 ton (51 kbtu heat, WF Series 7 rebranded) GeoStar Ashton 2 ton for DHW using a 50 gallon State electric heater for storage GeoStar IntelliZone2 - 4 zones (basement, first floor, master bedroom, other bedrooms) Aurora Web Monitoring Net Price: $28k after NYSERDA grants and tax credits The original proposal called for a 4 ton unit, however its output is only 43 kbtu so with the variable compressor and loop pump I thought it prudent to upgrade to the 5 ton unit. The cost increase was small. I want to preface my questions with the fact that I want to trust the contractor, however they haven't been able to produce loop design numbers which gives me some pause. I've asked all of these questions to them, but while I await a response I would love to hear opinions. At 51 kbtu this is equivalent to a 4.25 ton unit and the resulting loop field is 117 ft/ton. The contractor claims that by going with 1-1/2" pipe the resulting increase in flow will negate the smaller loop field. I've read on here that heat transfer is independent of pipe diameter and larger sizes only help with minimizing pumping pressure. Although they share the same loop field, they claim the hot water unit will have no affect on performance due to the shorter duty cycle. My opinion is mixed on this. I know it's not prudent to size for the full 22 kbtu additional, but is it acceptable to ignore it completely? For the DHW system, the storage tank they specified doesn't have connections to act as a hydronic zone for the Ashton unit, just cold in and hot out. I can't really envision how it would work without 4 connections, cold water in, hot water out, hydronic in, hydronic out.