Application Note: Basic Boiler Control

Solution:

Using a 75F Connect Module, a basic Boiler Plant can be controlled in the form of a simple configurable controller.  The Connect Module will have a predefined sequence that can be downloaded once connected to the CCU for a true plug-and-play experience and without the need to self-program.  All points will be viewed and configurable on the CCU and through Facilisight.

Note:

• This solution requires a hardwired RS-485 connection from the Connect Module to the CCU.
• The boiler plant may have control for up to 2 boilers, 1 mixing valve and 2 pumps with VFDs.
• Sequence will control boiler and pump lead/lag sequences.

System Points List:

Hardwired Inputs:

• Outdoor Air Temperature
• Supply (Leaving) Water Temperature
• Return (Entering) Water Temperature
• Loop Differential Pressure
• Boiler 1 Alarm (Hardwired)
• Boiler 2 Alarm (Hardwired)
• Pump 1 Status (0-10vdc = 0-20A)
• Pump 2 Status (0-10vdc = 0-20A)

Digital Outputs:

• Boiler 1/Boiler 2 Enable
• Pump 1/Pump 2 Enable
• Note: Outputs are 24vdc. Use isolation relays.

Analog Outputs:

• Pump 1/Pump 2 Speed
• Mixing Valve Position

Variables/Setpoints

• Supply (Leaving) Water Temperature Setpoint
  • May be Auto (180° at 20° Outside Air Temperature to 140° at 60° Outside Air Temperature) OR manually set in increments of 5 between 140° and 180°.
• Outdoor Air Temperature for System Enable
• Loop Differential Pressure Setpoint
• Pump & Boiler Rotational Sequence (Rotate manually or automatically)
• Time Duration to Rotate in Days