I have a new ground source system and have some issues that I am trying to sort out and was looking for some advice on sensors. The system was installed using strap on sensors (Tekmar) for providing data to the control units/data recording and some solar digital thermometers. These are located away from the unit on parts of the piping. My source delta T was about 6 degrees back in mid January in the recorded data. At the end of January I developed a refrigerant leak from the reversing valve. Finally got that replaced and the system recharged. However now the delta T is only a degree or 2 according to the sensors. The system runs and eventually gets to temperature. I checked the HE using the flow meters and the delta T. That indicated low charge. The digital thermometers read a higher delta T, but I question their accuracy as the combined source temp reads lower than any of the individual sources. I do not think that their wells were installed correctly. I am down to that I have either bad sensors or I have low refrigerant. There are no P/T ports on the system, but I am willing to make changes so that I can get more accurate data. I have tried using a strap on TC on the source fittings, but I get a lot of variability. Trying to get the tech back here to check superheat, but frozen systems are taking priority. So any advice on sensors would be appreciated.