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Chiller Controller



The SZ2166 is a microprocessor-based chiller controller for use on multi-stage chiller applications. It includes boiler support and control functions.



  • Six 1000Ω PtRTD, momentary override
  • Five digital (dry contact)
    • Chilled water supply and return: 0 to 100°F
    • Hot water supply and return: 40 to 240°F
    • Mixed water: 20 to 220°F
    • Outdoor air: –40 to 160°F


  • Nine digital (SPST dry contact, 24 VAC @2A)
  • Two 4 – 20 mA DC analog

Maximum load resistance (analog output):


Common mode rejection: 

100 db @60Hz


  • Stand-alone or network operation
  • 365-day time clock with two holiday schedules, automatic leap year and daylight savings correction
  • Hot water supply-and-return temperature inputs
  • Boiler support
  • Separate setpoint for thermal storage sequence
  • Outdoor air reset control
  • Two digital inputs for pump status
  • Lead/Lag sequencing of up to six chillers
  • Two modulating analog outputs for valves and VFDs
  • Adjustable P+I+D control on modulating outputs
  • Automatic rotation of pumps
  • Automatic rotation of chiller and boiler stages
  • Pump lube feature
  • Local and remote override capability

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