Applications Guide Tracer Graphical Programming - Trane

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Writing the discharge air control program
Figure 148: Controlling the cooling valve
Controlling the heating valve
The following may be derived from the sequence of operation for the heating
valve. Note the additional requirement regarding dehumidification.
Modulatetheheatingvalvetomaintainthedischargeairtemperatureat
the discharge air heating setpoint when all of the following are true:
• The supply fan is on.
• The air handler is in heating mode.
Or when all ofthefollowingaretrue:
• The supply fan is on.
• Dehumidification is enabled.
Open the heating valve completely when both ofthefollowingaretrue:
• The supply fan is off.
• The outdoor air temperature falls below the adjustable freeze avoidance
setpoint.
Close the heating valve when any of the following is true:
• The air handler is in cooling mode, and dehumidification is disabled.
• The supply fan is off.
• The discharge air temperature sensor is failed.
CNT-APG001-EN 171