Chapter 4 Sequence Of Operation; Control Modes; Space Temperature Control - Trane Tracer AH540 Setup And Operation

CNT-SVX05B-EN
Chapter 4
Sequence of operation
The Tracer AH540/541 is a configurable controller. All of the controller
sequences of operation are predefined with no need for programming the
controller. Configurable parameters are provided to allow the user to
adjust the controller operation. For example, the minimum occupied out-
door air damper position can be changed.
All configuration parameters are set to defaults predetermined through
extensive air-handling unit testing in several different operating condi-
tions. The factory default settings are also based on the air-handling unit
configuration and order information.

Control modes

The Tracer AH540/541 controller is configurable to operate in one of two
air-handling temperature control modes:

Space temperature control

•
Discharge air temperature control
•
When the AH540/541 is configured for space temperature control, it con-
®
forms to the LonMark Space Comfort Controller (SCC) profile. When the
AH540/541 is configured for discharge air temperature control, it con-
®
forms to the LonMark
Note:
Some sequences in this chapter are specific to the space tem-
perature control mode and some are specific to the discharge air
temperature control mode. Some sequences are common to both
modes, but operate differently. Where mode-dependent differ-
ences exist, they are explained in this chapter.
Space temperature control
The Tracer AH540/541 controller requires both a space temperature and
discharge air temperature sensor to be present for space temperature
control operation (also called cascade control). In this control mode, the
Tracer AH5405/541 uses the space temperature and the measured dis-
charge air temperature to maintain the space temperature at the active
space cooling setpoint or the active space heating setpoint. The controller
modulates its heating or cooling outputs to control the discharge air tem-
perature to the discharge air temperature setpoint. This calculated dis-
charge air temperature setpoint is the desired discharge air temperature
Discharge Air Controller (DAC) profile.
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