Trane TRG-TRC014-EN manual Morning Warm-up/Cool-downMode, System Configurations, period three

period three

System Configurations

notes

Morning Warm-up/Cool-down Mode

▲Main supply fan operates continuously

▲Main supply fan controlled to maintain the system static-pressure set point

▲Outdoor air damper is closed, unless required for preoccupancy purge

▲Terminal units are either fully open or modulated to maintain their respective “occupied” space thermostat set points

Figure 70

The morning warm-up/cool-downmode typically occurs as a transition from the unoccupied mode to the occupied mode. It establishes the occupied comfort conditions for the building as rapidly as possible, because they were allowed to drift from occupied set point during the unoccupied mode, usually to save energy.

In this mode, the building does not initially require ventilation because it is not occupied, but it may eventually be provided for a preoccupancy purge (diluting the contaminants that accumulated during the unoccupied mode).

During the morning warm-up/cool-down mode, the system is controlled as follows:

nThe AHU fan operates continuously to provide primary air to the spaces for cooling or heating. If separate perimeter heat is installed and heat is demanded, the perimeter heat source operates and the AHU fan remains off.

nThe supply fan is controlled to maintain the static-pressure set point for the system.

nThe outdoor air damper is closed unless ventilation is needed for preoccupancy purge.

nThe terminal units may be fully open, allowing “wild” (uncontrolled) warm- up or cool-down, or they may modulate to achieve the occupied temperature set points for a “controlled” warm-up or cool-down.

Morning warm-up or cool-down mode is ended when the perimeter zone thermostats or a single, representative thermostat reaches its occupied set point. Then the system switches to the occupied mode.

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