ZN-T Setpoint Determination - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 15.0

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
15.0
Revision date
2022-11-18
Language
English

The configuration options for the ZN-T Setpoint Determination module are done with a combination of system selection choices under the Temperature/Setpoint Adjust section of the selection tree and the module’s configuration settings in the Details dialog box. The resulting configuration provides the Zone Setpoints for Heating and Cooling used by any applications configured for a zone temperature control strategy.

The following block diagram highlights the standard and optional interfaces to this module.

Figure 1. ZN-T Setpoint Determination Interfaces

During the System Selection process for any Zone Temperature controlled application, you have the following options to determine how to integrate the Network or local Zone Setpoint interfaces. Under the Temperature/Setpoint Adjust selection:

  • If no options are selected, then only a Network Input for Zone Setpoint is created (ZNT-SP).

  • If a Common Setpoint Adjust option is selected, then an Analog Input is created for a Zone Setpoint (ZN-SP). You can also manually add a Network Zone Setpoint (ZNT-SP) and make a connection to the Network Setpoint of the module. For this scenario, the Analog Input for the local Zone Setpoint is configured as the backup to the Network Zone Setpoint when communication is lost from the Network. To make the local Zone Setpoint the backup, open the Details dialog box of this module and modify the Remote Setpoint Mode attribute.

  • If the Warm-Cool Adjust option is selected, then a Warmer Cooler Offset Analog Input (WC-ADJ) is created along with a Network Input for the Zone Setpoint (ZNT-SP). In this case, the Warmer Cooler Adjustment value configured at the local Zone Temperature Setpoint offsets the value of the Zone Setpoint value from the Network Input for the Zone Setpoint. The offset range for the Warmer Cooler Adjustment is configured in its Input Detail dialog box for this input.

To derive the Effective Heating and Cooling Setpoints, you must first understand the default settings for the key Setpoint values (Table 1). In the Parameters table or Details dialog box for this module, you can edit the default heating and cooling setpoints for each Occupancy mode. You also can set the default value for the Network or Local Zone Setpoint in their respective Details dialog box.

The Default Value for the Network or Local Zone Setpoint is 72.

Table 1. Key Setpoint Values

Setpoint

Value

Occ Cooling Setpoint

74

Occ Heating Setpoint

70

Standby Cooling Setpoint

77

Standby Heating Setpoint

66

Unocc Cooling Setpoint

82

Unocc Heating Setpoint

61

If these values are never adjusted, the system uses the Occupied, Standby, and Unoccupied Heating or Cooling Setpoints as the Effective Heating and Cooling Setpoints. This scenario occurs based on the state generated from the Occupancy Mode Determination State Generation module.

As you change the Network or Local Zone Setpoint, the module automatically derives an Absolute Setpoint Offset Value (AbsOffset). The Absolute Setpoint Offset (AbsOffset) is calculated as the difference between the Network or Local Setpoint and the mean of the Occupied Heating and Occupied Cooling setpoints.

Absolute Setpoint Offset (AbsOffset) Calculation:

AbsOffset = Network or Local Setpoint - AVG (Occ Cooling Setpoint, Occ Heating Setpoint)

Based on system default values, the AbsOffset = 72 - AVG (74 - 70), which equals 0.

For example, assume the Network or Local Setpoint is changed from 72 to 70 and the Occupied Cooling and Heating Setpoints remain at their default values of 74 and 70. The AbsOffset value is now -2. The value of -2 is now added to established Cooling and Heating defaults to derive the Effective Cooling and Heating Setpoints (when Occupancy Mode is not set to Unoccupied). When the Occupancy Mode is set to Unoccupied, the AbsOffset is not used, the EFFCLG-SP equals CLGUNOCC-SP, and the EFFHTG-SP equals HTGUNOCC-SP.

In a scenario where the Warm Cool Adjust option was selected for the zone sensor interface, the offset value provided from this local adjustment is added to the AbsOffset calculation. For example, assume that all of the default values for the Network Zone Setpoints and Mode Heating and Cooling Setpoints were set up with the Warm Cool Adjust option. If you adjust the Warmer/Cooler setting at the zone sensor from 0 to -2, the AbsOffset value is -2.

You also can limit the range of the Network or Local Setpoint adjustments. In the Details dialog box for the module, you can configure the Maximum and Minimum settings for both the Heating and Cooling Setpoints. These limits take precedence over any default setpoints created per Occupancy Mode.

For configurations with Optional Summer Winter Compensation, the Effective Heating and Effective Cooling Setpoints are derived based on setpoint shift values, and are included in the calculation for the Absolute Offset Value. See the Summer Winter Compensation module to see how it uses Outdoor Air Temperature to derive the offset used by this module.

For configurations with integrated Warmup/Cooldown logic, the Details dialog box of the Zone Setpoint Configuration module allows you to set the occupancy modes during the Warmup, Cooldown, and Coast modes generated by the WarmupCooldown Sequencing State Generator.

You cannot view or modify the modules in this group’s logic.