What would be a typical range of total gallons of liquid in a 6-ton closed loop system handling a 3800 square foot home? I read 60-80 gallons in one place which would suggest up to 20 gallons of polyethylene glycol for 25% refrigerant.
It depends on the total diameter(s) and lengths of the pipes in your loop field, which could vary with the design of the loop. Your figure of 60-80 gallons sounds small to me. I have a 4T system with 4,200 ft of 0.75" pipe and about 400 feet of 2" supply and return pipe. That required 196 gallons total.
Thanks for that. If they had to completely refill ours, ( say its capacity is 250 gallons ) including 25% refrigerant of some kind, it might then require ~60 gallons of refrigerant. Based on $900 for a 55 gallon drum, we'd be looking at ballpark $1000 just for the refrigerant.