Application Note: Steam Heat Exchanger Control

Solution:

Using a 75F Edge 10, a steam heat exchanger can be controlled in the form of a simple configurable controller.  The Edge 10 will come pre-programmed for a true plug-and-play experience and without the need to self-program.  We will also provide parameters for PID loop tuning on the CCU so access to the wire sheets and point configuration is not needed.

Note:

• This solution does not require an internet connection to the Edge 10, only to the CCU.
• The solution controls two modulating valves (1/3 valve and 2/3 valve) based on supply water temperature.
• The controller does not include pump control.  See the following application note:
  • 75F Pump Control
• Heat Exchanger controller provides a digital output to enable the pump system.
• The Heat Exchanger system requires a pump status or flow switch (configurable) in a digital signal.
• System will be enabled on an adjustable outdoor air temp setpoint.
• Supply water temperature setpoint is reset based on Outdoor Air Temp.
• Requires a 2-10 vdc actuator for both valves.

VFD Points List:

Hardwired Inputs:

• Supply Water Temp
• Return Water Temp
• Outdoor Air Temp
• Loop Flow
• Pump Status

Digital Outputs:

• Pump System Enable

Analog Outputs:

• 1/3 Valve Position Command
• 2/3 Valve Position Command

Integrated Inputs

• Outdoor Air Temp System Enable Setpoint
• Supply Water Temp Alarm
• Supply Water Temp System Lockout
• Supply Water Temp System Lockout Reset
• Loop Flow or Pump Status Enable Selection
• Loop Flow/Pump Status System Enable Delay
• Supply Water Temp Setpoint Reset Min/Max
• Outdoor Air Temp Setpoint Reset Min/Max
• PID Loop Tuning for Valves
  • Proportional
  • Integral
  • Derivative
  • Bias
  • Minimum Output
  • Maximum Output
  • Ramp Time (Minutes)