• Document: MLCFC Technical Service Manual
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MLCFC 200-1200 Technical Service Manual Motivair Corp. 85 Woodridge Drive Amherst, NY 14228 Phone 716-691-9222 Fax 716-691-9229 www.motivaircorp.com Rev.102111RJ Table of Contents 1. About This Manual 2. Sequence of Operation 3. pCo Information • HMI Screen Navigation • Input and Outputs • Alarm Troubleshooting • pCo Layout • pCo Smart Key Download 4. Compressor Information • Pump down • Oil Differential Switch • Oil Float Switch • Oil Change – Filter Replacement • Protection Module (INT69Y) • P&I 5. Condenser Fan VFD Information 6. Temperature Probe(s) Information 7. Electrical Monitor Information • RVG • CF1 and CF2 8. Electronic Expansion Valve Module (EEV) Information 9. Communication Information • Modbus • pCo Web (Ethernet) – Bacnet 10. Hydraulic Information • Evaporator Flow Switch • Free Cooling Valve • Glycol Chart About This Manual • WARNING: THIS MANUAL IS A SUPPLEMENT TO THE O & M MANUAL - ALL WARNINGS, INSTRUCTIONS, AND SAFETY PROCEDURES LISTED IN THE O & M MUST BE STRICTLY FOLLOWED. A COPY OF THE O & M MANUAL IS AVAILABLE AT http://www.motivaircorp.com/literature • WARNING: THIS MANUAL IS A REFERENCE FOR QUALIFIED CHILLER REFRIGERATION TECHNICIANS ONLY. • WARNING: THE PROCEDURES OUTLINED IN THIS MANUAL ARE SPECIFIC TO THE CHILLER MODELS LISTED. NO ATTEMPT IS MADE IN THIS MANUAL TO BE A COMPLETE OR EDUCATIONAL TEXT. • WARNING: INDUSTRY STANDARDS FOR REFRIGERATION SERVICE AND REFRIGERANT HANDLING PRACTICES AS PRESCRIBED BY. THE FEDERAL CLEAN AIR ACT (SECTION 608), ARI, ACCA, EPA, OSHA, AND ANY LOCAL GOVERNING ORGANIZATION THAT HAS JURISDICTION MUST BE FOLLOWED. ALL TECHNICIANS WHO HANDLE REFRIGERANTS MUST BE CERTIFIED. • WARNING: THIS MANUAL COVERS ONLY THE CHILLER MODELS MANUFACTURED PRIOR TO THE REVISION DATE – CONTACT MOTIVAIR FOR THE LATEST REVISION. • WARNING: RECOMMENDATIONS AND REQUIREMENTS ARE STATED THROUGHOUT THIS MANUAL. THE REQUIRED REFERENCES ARE TO PRESERVE ANY WARRANTY STATUS. MLCFC Sequence of Operation Mechanical cooling – outlet control On a call for cooling set point = 45*F glycol pump running flow switch closed the first stage compressor starts and runs at 25% loaded for 30 second then stages up to 50% at this point the control reads the outlet temperature if the temperature is within 1.8*F of set point the compressor holds at the present stage. If the outlet temperature rises over 1.8*F and the 90 sec staging timer has expired the compressor will stage up to 75%. After 90 more sec if the outlet temp is >1.8*F the compressor will stage up to 100%. After another 90 seconds if outlet temp is still outside the 1.8*F (dead-band) the second compressor will start and load up to 50% and so on until the outlet temperature is = to or < 1.8*F above set point. As the loop temp falls, the first compressor on will start to stage down at 90 sec intervals to maintain set point. With the compressor rotation FOFO (first on first off) the next compressor to start will be the second stage. Partial free cooling (pre-cooling) Cooling set point = 45*F Ambient = 46*F Outlet Water Temp (OWT) = 45*F Inlet Water Temp (IWT) = 55*F At these conditions the chiller is running in 100% mechanical cooling as the ambient temperature falls to a point = to 9*F below the IWT (i.e. 55*F - 9*F = 46*F) the free cooling valve cycles to the free cooling position diverting the 55*F IWT to the free cooling coils. At this point the 46*F ambient temperature is passed across the free cooling coils and pre-cools the IWT dropping the temperature before entering the evaporator thus reducing the load on the compressors which will stage down to maintain set point reducing the energy consumption of the chiller. Total 100% free cooling Cooling set point = 45*F Ambient = 26*F Outlet Water Temp (OWT) = 45*F Inlet Water Temp (IWT) = 55*F At these conditions the chiller is operating in partial free-cooling as described above with the compressor(s) online and available for added mechanical cooling to meet set point. As the ambient continues to fall to a point = to or > 29*F below the IWT (i.e. 55*F – 29*F = 26*F) the mechanical cooling is locked off as the chillers full tonnage capacity is available by design at this ambient temperature. The condenser/free-cooling fans VFD will modulate on the outlet temperature to maintain set point within 1.8*F. The compressors will stay locked out until the ambient rises to a point where free cooling cannot be maintained. The advantage to this chiller system is that the integration of the free cooling, the mechanical cooling, and the single control system that operates both in one unit. This integration takes a

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