Operation - Johnson Controls - LIT-12011950 - Building automation software - Smart Equipment Controller - 5.0

Smart Equipment Controls Sequence of Operation Technical Bulletin
Product
Building Automation Systems > Building Automation Systems > Smart Equipment Controller
Document type
Technical Bulletin
Document number
LIT-12011950
Version
5.0
Revision date
2024-06-06
Product status
Active

Normal occupied operation mode

If the return humidity is greater than or equal to the hot gas reheat humidity setpoint and there is no demand for cooling, the C1 output energizes and the AUX-HGR output energizes. The control remains in this state until the humidity drops below the HGR humidity setpoint differential (HGR-Diff).

If there is a demand for one stage of cooling and the return humidity is greater than or equal to the hot gas reheat humidity setpoint, the C1 output energizes but the AUX-HGR output de-energizes.

Any additional cooling demands energize compressor outputs but do not change the status of the AUX-HGR output.

Note: If the parameter HGR enabled for unoccupied operation is enabled during unoccupied mode, the control works the same as described above and uses the HGR unoccupied humidity setpoint instead.

Alternate mode

If the return humidity is greater than or equal to the hot gas reheat humidity setpoint and there is no demand for cooling, the C1 and AUX-HGR outputs energize and C2 energizes. The control remains in this state until the humidity drops below the HGR humidity setpoint differential.

If there is a demand for one stage of cooling and the return humidity is greater than or equal to the hot gas reheat humidity setpoint, the C1 and AUX-HGR outputs energize and C2 energizes.

If there is a demand for both first and second cooling stages and the return humidity is greater than or equal to the hot gas reheat humidity setpoint, the C1 and C2 outputs energize and AUX-HGR de-energizes.

Note: If the parameter HGR enabled for unoccupied operation is enabled during unoccupied mode, the control works the same as described above and uses the HGR unoccupied humidity setpoint instead.

Table 1 describes the dehumidification sequence for both the standard and alternate modes. This table applies as long as the return humidity is greater than or equal to the HGR humidity setpoint.

Table 1. Dehumidification sequence in normal and alternate mode
Request Normal mode Alternate mode
HGR C1 C2 HGR C1 C2
Dehumidification On On Off On On On
One stage of cooling (Y1) Off On Off On On On
Two stages of cooling (Y2) Off On On Off On On
Note: The demands for cooling are defined in the sensor operation.

Hybrid mode

Hybrid mode enables a second stage of cooling with a dehumidification call. This adds capacity to remove humidity from the air but it may also lead to over cooling if there is no thermal demand in the space. Hybrid mode combines alternate mode and normal mode, and selects the appropriate mode in relation to the cooling staged percent command value.

If hybrid mode is on, one of the following sequences occur:

  • Dehumidification call with cooling staged percent command = 0%: the control overrides to normal mode
  • Dehumidification call with cooling staged percent command > 0%: the control overrides to alternate mode

If hybrid mode is off, the control uses the configured mode and does not switch modes based on the thermal load in the space.

Hybrid mode is disabled by default. You can enable hybrid mode through the MAP Gateway or the UCB:

  • MAP Gateway: Commissioning > HGR > Hybrid Mode > On/Off
  • Local UI: Details > HGR > Setup > Hybrid Mode > On/Off

The enable point for hybrid mode is not available in BAS front ends as a setup parameter.

Overcooling Limit

If operational space temperature gets within one degree of the heating setpoint, the unit exits hot gas reheat mode.