Specifications

30 Centrifugal Chillers IMM WMC-2
Operating Sequence
For multiple-chiller, parallel operation, the MicroTech II controllers are tied together by a communications
network and stage and control compressor loading among the chillers. Each compressor, single or dual
compressor chiller, will stage on or off depending on the sequence number programmed into it. For example, if
all are set to “1”, the automatic lead/lag will be in effect.
When chiller #1 is fully loaded, the leaving chilled water temperature will rise slightly. When the Delta-T above
setpoint reaches the Staging Delta-T, the next chiller scheduled to start will receive a start signal and start its
pumps if they are set up to be controlled by the MicroTech II® controller. This procedure is repeated until all
chillers are running. The compressors will load-balance themselves.
If any of the chillers in the group are dual compressor, they will stage and load according to the staging
instructions.
See OM WMC (current edition) for a complete description of the various staging sequences available.
Prestart System Checklist
Yes No N/A
Chilled Water
Piping complete .......................................................................................   
Water system filled, vented ......................................................................   
Pumps installed, (rotation checked), strainers cleaned.............................   
Controls (3-way, face and bypass dampers, bypass valves, etc.) operable   
Water system operated and flow balanced to meet unit design requirements   
Condenser Water
Cooling tower flushed, filled and vented ................................................   
Pumps installed, (rotation checked), strainers cleaned ............................   
Controls (3-way, bypass valves, etc.) operable .......................................   
Water system operated and flow-balanced to meet unit requirements .....   
Electrical
Power leads connected to the unit power panel(s) ..................................   
All interlock wiring complete between control panel and complies with specifications   
Pump starters and interlock wired ...........................................................   
Cooling tower fans and controls wired ....................................................   
Wiring complies with National Electrical Code and local codes ............   
Condenser pump starting relay (CWR) installed and wired ....................   
Miscellaneous
Relief valve piping complete ...................................................................   
Thermometer wells, thermometers, gauges, control wells, controls, etc., installed   
Minimum system load of 80% of machine capacity available for testing
and adjusting controls .............................................................................   
Control wiring between multiple units, if applicable.........................................................   
Note: This checklist must be completed and sent to the local McQuay Factory Service location two weeks prior
to start-up .