Hi Everybody! I inherited an R-22 parallel compressor (vilter 350xl) system used as a chiller in air separation plant. Started out with a rebuild(all but crankshafts) on both units. Found bad valves, replaced rings, one piston, rod brngs, etc. Plant super said he never heard them run so smooth. Him now retired. Me new to refrigeration. 1st problem- expansion valve (float controlled) is in parallel with a manual valve, which retired guy adjusted every day to keep a decent level in evaporator(this was his baby-wouldn't let anybody else touch it!) It wouldn't keep level in evap. anymore and plant guys up there spinning valves eventually had the whole system upset. Of course no records! I went up and used that manual valve to get the thing under control- I want auto valve to handle it! Ordered new control valve and float chamber, sized to fit system(springs and piston correct)and installed. Found that the liquid line to the float and vapor return to evap. way undersized. Ran another tube in parallel, that helped. Gonna replace both at next opportunity. Increased the temp of air going into evap. could only get discharge pressure up to 170 psi, suction pressure steady at 60 psi.(when i gave specs on system I said 160psi and 60psi and 64.5 tons) We also run a water cooling tower in the summer and swtch to glycol in the winter. Its running well now but still needs adjustments on manual valve once in a while. Lets call this chapter one of my story- don't want to bore anyone!