Hi. New to the forum and am trying to troubleshoot our geo system. Any thoughts or suggestions would be appreciated! (Sorry I may not have all the specs needed (like soil conditions etc) to be able to figure out the answer) New construction home. 2 floors and unfinished basement, which does not have HVAC. Approximate sq ft of finished space is 5,400. HVAC consists of horizontal closed loop geothermal. 2 geo units. Climate Master *Tranquility27 split unit (air handler in attic) for upstairs -- 3 tons (12,000W aux electric heat) *Tranquility30 for main floor -- 4 tons (15,000W aux electric heat) Total ground loop is 4,740’ Consists of (8) 1 ¼" loops We have 4 trenches (supposedly) 8’ deep and 4’ wide with (2) loops per trench Header pipe is 500’ and 1 1/4” diameter. (250’ from house to loop connection and 250’ from loop connection back to house) We cannot confirm how the loops are connected together (ie series or parallel, or if there is reverse return flow etc) Brief synopsis: We have never been able to heat our house adequately in the colder portion of the winters without using space heaters and running fireplaces (or noticing that we are running a lot of time on the aux heat). Can only get temp to 68 or so with geo HVAC alone. We have upsized interior pipes to/from the geo units to the loop field (from 1 1/4” to 1 1/2” where the outdoor underground header pipes remain 1 1/4”), added an in line booster pump, replaced both a geo unit variable speed pump as well as failed compressor. Have had to fix numerous interior pipe leaks and also flush out a significant amount of air that was in the loops. Most recently, systems have locked out completely this summer (which necessitated the leak repair, air flushing, and compressor replacement). Basically, when both geo units are running, they seem to be starving each other and locking out or operating just below lockout threshold (and thus not heating or cooling us to desired temp). When one unit alone (whether the 3 ton or 4 ton system) is running, we are getting upwards of 8.5-9GPM flow. When both are running, max flow is no better than 11GPM total (each unit only being able to get up to 5.4GPM). Also, the heat pumps (despite having a variable speed pump) seem to always be running at 90% capacity even now with more mild temperature. Would digging up the 500’ header 1 1/4” pipe and upsizing it to 1 1/2” (or larger) help achieve the flow we need (based on ClimateMaster recs of 2.5-3GPM per ton in a closed horizontal loop system) or could the horizontal loop field itself or how it is all connected together be the culprit? Should I be ignoring GPM and looking at some other variable (such as delta T, which I understand is dependent on GPM anyhow) to know that our system is functioning appropriately? Thanks in advance for any suggestions/thoughts!