A customer of ours has twin York Chillers YCWS0140 and BAC towers VT0-132-LD. The System orginally had Trane Chillers until lightning had its way with them. The system was using an economiser system which would use tower water under 45 degrees, through a heat exchanger to provide cooling. The heat exchanger system from what I was told never really worked that well and they abandoned it when the chillers were changed and had a controls upfit.
The problem is now when the water gets below 70 degrees the chillers lock ou on low oil pressure differential due to the pressures running too low. I think the Trane systems used hot gas bypass to eliviate this. The Yorks don't have HGBP.
My question is what is the best way to control the low end tower water temp to control head pressure? HGBP? Condenser water valve with head pressure control? Recirculation loop? Thanks