refrigerant contained in the system 39 s filter dryer 46 for example a parker bi directional r 410a heat pump filter dryer model bf164 xf holds about 0 761875 pounds exclusive of any filter dryer in the compressor box 49 which has already been taken into account in the compressor unit box 49 content e add the amount of liquid refrigerant in all liquid line ball cut off valves 45 and 48 typically about 0 05 pounds each exclusive of the ball cut off valves if any in the compressor box 49 which have already been taken into account in the compressor unit box 49 content f measure the total liquid transport line 55 length between the top 56 of the well borehole 7 shown here at the ground surface 4 and the compressor unit box 49 and multiply by the full liquid refrigerant weight content of the liquid refrigerant transport line 55 in pounds for example multiply by 0 0375 pounds if it is a preferred u215c inch o d refrigerant grade copper line 55 but multiply by 0 06875 if it is a u00bd inch o d refrigerant grade copper line although the liquid transport line 55 is shown here as being located between the top 56 of the well borehole 7 and the compressor unit box 49 at an above ground surface 4 location this segment of the liquid transport line 55 is typically buried below the ground.