Ok, things are up and going well, we have just over 30 days of data recorded by the welserver and the system is delivering as designed. Equip review: Location: Central Michigan ClimateMaster TT 27 072 (6 ton) Horizontal closed loop (3/4) buried at 8ft, 4800 Ft pipe - 20% Methonal QT (non-pressurized) flow center (2 pumps) What should the delta be running? I throttled back the return a little and it went from 3-4 to 5-6, now averaging closer to 6 as the EWT water temps drop below 60. I'm using the pressure difference to calculate the flow, but I'm thinking I will probably need to get a flow meter soon to get more accurate data and ensure I maintain the flow rate range required. As I throttled back the return a little, the pressure went up on both sides, I'm assuming this is normal? I've checked those around me and there are welservers showing a delta as low as 3 and as high as 8... I'm assuming that higher is better? Of course their equipment is all different, including their water sources... Is there a correlation? Your thoughts?