Chapter 4 Input/output functions and wiring for typical applications
For units not configured as changeover units, the entering water temper- ature value is used for information and troubleshooting only and does not affect the operation of the controller.
Note:
AI1 is not polarity sensitive; you can connect either terminal to either sensor lead.
AI2: Discharge air temperature
The AI2 analog input functions as the local discharge air temperature input.
IMPORTANT
The Tracer ZN521 cannot operate without a valid discharge air tempera- ture value.
The controller receives the temperature as a resistance signal from a
10 kΩ thermistor wired to analog input AI2. The thermistor is typically located downstream from all unit heating and cooling coils at the unit dis- charge area.
If a discharge air temperature value is invalid or is not present, the con- troller generates a Discharge Air Temp Failure diagnostic and shuts down the equipment. When the thermistor returns to a valid tempera- ture, the controller automatically allows the equipment to resume normal operation.
Note:
AI2 is not polarity sensitive; you can connect either terminal to either sensor lead.
AI3: Outdoor air temperature or generic temperature
The AI3 analog input can function as either:
•An outdoor air temperature input
•A generic temperature input
If AI3 is configured as the local
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