11,000 BTU DX GEO Heating

[MEMPHIS91]

I assure you that ever post you have made gave me a AHA! moment. And I then scratch my head for several hours/days to figure out what I didn't understand. So again I say thank you.

Yes I know a larger compressor will change everything. But I do not believe this system is capable of doing what I really need it to with the 7,500btu. I have my eyes on a 9,900btu 3/4hp 115V 60Hertz 51LRA beauty. Most my real tuning should probably wait til then. I was just getting a good fill of things and a decent charge because temps have been colder lately. Low of 23F tonight.
I fill that one day I will be digging around the water tank in order to insulate it because heating the water is much easier and more important than air temp.
I know that the evap can handle the larger compressor. And I can always add another coil in both the water or air condenser if needed. I have come this far I don't know why I would settle for less.
Since this system is heating only, meaning no running at all during the summer, is finding the critical charge that important? I am guessing it will run almost 3/4 to all night tonight to keep up.
I guess I don't understand why the critical point is needed other than for safety. I have a 345psi shut off ready to braze on when I get the larger compressor.
I do understand that I should tune everything to the air side though. Because the water loop will always run less head pressure.

Thanks again man