Trane Tracer AH540, Installation Owner Diagnostics

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CNT-SVX05A-EN
Sequence of operation
Table 23 — Constant volume unit operation allowed based on communicated
request
Note 1: Enabled means normal operation.
Disabled means that the controller cannot use it.
Note 2: The Tracer™ AH.540 controller does not support Emergency heat. Emergency heat will be treated as Auto.
Automatically by the controller
A communicated request of Auto or the controller's default operation (Auto) can
place the unit into heating or cooling mode. When the controller automatically
determines the heating or cooling mode while in Auto mode, the unit switches
to the desired mode based on the control algorithm.
If the Tracer AH.540 controller is operating space temperature control,
it uses the space temperature and space temperature setpoint to automatically
determine heat or cool mode of operation. When the controller first powers up
or after a reset, it makes an initial determination if the heat/cool mode should
be heat or cool. If the controller is configured as heating and cooling, the
controller determines the appropriate mode.
Example: If the initial space temperature is less than the occupied space heat
setpoint then the initial heat/cool mode is heating. The heat/cool mode for a
cool-only unit is always cool. The heat/cool mode for a heat-only unit is always
heat.
When the controller is allowed to automatically determine its space heating and
cooling mode, the unit changes from cool to heat or from heat to cool, when
the integrated error between the active space setpoint and the active space
temperature is 900
°
F • seconds or greater. The integrated error is calculated
once every ten seconds.
See Figure 8 below for an example of the controller changing from space
cooling (Unit Mode = cool) to space heating (Unit Mode = heat). In this example
the controller’s initial unit mode is cool because the space temperature is above
the cool setpoint, and the controller's cooling capacity is greater than 0%.
Following the curve from left to right, the space temperature falls below the cool
setpoint and the controller reacts by lessening its cooling capacity.
When the space temperature reaches
1
, the controller's capacity is 0%.
The rate at which the controller reaches 0% capacity depends on the space
temperature rate of change.
Request
(Note 1) Supply fan Mechanical
heating Mechanical
cooling Outdoor air damper Exhaust fan
Auto Enabled Enabled Enabled Enabled Enabled
Heat Enabled Enabled Disabled Enabled Enabled
Morning
warm-up Enabled Enabled Disabled Closed Disabled
Cool Enabled Disabled Enabled Enabled Enabled
Night purge Enabled Disabled Disabled Ventilation disabled
Economizer enabled Enabled
Pre-cool Enabled Disabled Enabled Ventilation disabled
Economizer enabled Disabled
Off Disabled Disabled Disabled Disabled Disabled
Test Enabled Enabled Enabled Enabled Enabled
Emergency
heat
(Note 2) Enabled Enabled Enabled Enabled Enabled
Fan only Enabled Disabled Disabled Disabled Enabled