Setting the temperature control and flow parameters - Verasys - LIT-12012371 - LC-SBH200-0 - Building automation software - Verasys System - 4.2

Verasys System User Guide
Brand
Verasys
Product name
Verasys System
Document type
User Guide
Document number
LIT-12012371
Version
4.2
Revision date
2023-06-15
Product status
Active
Language
English
  1. Select the Commissioning tab to set the flow, demand control ventilation (DCV), and Title 24 Load Shed parameters. To ensure proper temperature control, use the design flow schedule for the system, which is usually found on the mechanical plans for the job, to set the following flow parameters:
    Note: The VAV box controls the amount of supply air from the unit into the VAV box. It is not the flow coming out of the box. Equipment such as a series fan, could increase the flow leaving the box.
    1. Cooling Max Flow – Sets the maximum supply air flow of the VAV box when cooling. Adjustable: 0 cfm to 10,000 cfm.
    2. Cooling Min Flow – Sets the minimum flow that enters the box when it is satisfied after cooling. Adjustable: 0 cfm to 10,000 cfm.
    3. Occupied Heating Min Flow – Sets the minimum supply air flow of the VAV box when heating. Adjustable: 0 cfm to 10,000 cfm.
    4. Staged Reheat Min Flow – Sets the minimum heating flow for electric reheat control. This parameter serves an additional control safety to the high-limit switches in the box. It is best practice to set this parameter to 70 cfm per kW of electric heat. Adjustable: 0 cfm to 10,000 cfm.
    5. Unoccupied Cooling Min Flow – Sets the minimum supply air flow of the VAV box when in unoccupied cooling mode. Adjustable: 0 cfm to 10,000 cfm.
    6. Unoccupied Heating Min Flow – Sets the minimum supply air flow of the VAV box when in unoccupied heating mode. Adjustable: 0 cfm to 10,000 cfm.
    7. Supply Area: The supply inlet area used to calculate the supply flow. Adjustable: 0 sq. ft to 8.0 sq. ft.
    8. Pickup Gain: Shows the K factor for the box. This parameter calibrates the flow. Adjustable, see Appendix A: Johnson Controls manufactured VAV box characteristics for the pickup gains, and for directions on how to close JCI brands of VAV boxes. Each manufacturer has different pickup gains (K Values) associated with their air flow rings. Check with the manufacturer for their values.
      Note: Set Occupied Cooling and Heating Min Flow at least 10% higher than Staged Reheat Min Flow.
  2. After you have set the flow parameters, it is best practice to issue an auto calibration command. You must have air flow coming from the unit before you do this.
    1. To start an auto calibration, set the Auto Calibration Command parameter to True. The auto calibration drives the damper closed and your velocity pressure must read near zero. The Auto Calibration Offset parameter is set to this value and the box reads zero flow.
      Note: A common issue is incorrect damper polarity. The damper does not close, but instead it opens fully and offsets the flow. Ensure the damper polarity set in Configuring a VAV controller for a VAV system (ZEC510) for temperature and flow control is correct.
    2. When the Auto Calibration Status parameter shows that auto calibration is complete, set Auto Calibration Command to False.
  3. Select the Control Setup tab and check that each parameter is set to customize the zone to the customer’s needs. For example, check if a Warmer cooler adjustment is needed or if you need temporary occupancy.
    Note: See Appendix B: Objects and parameters for information about the controller parameters.

Your supply air flow controls to the supply air setpoint. The supply air setpoint increases from minimum to maximum depending on the temperature demand of the zone. You can use the Trends tab to diagnose issues and see the history of the zone temperature.