UNT-SVX07B-EN 107
Diagnostics
Translating Multiple Diagnostics
The controller senses and records each diagnostic independently of other diagnostics. It is possible
to have multiple diagnostics present simultaneously. The diagnostics are reported in the order they
occur.
Possible diagnostics include:
• Low temperature detection
• Condensate overflow
• Low air flow—fan status
• Discharge air temp limit
• Space temperature failure
1
• Entering water temp failure
1
• Discharge air temp failure
1
• Outdoor air temp failure
1
• Local setpoint failure
1
• Local fan mode failure
1
•CO
2
sensor failure
1
• Generic AIP failure
1
• Humidity input failure
1
• Defrosting compressor lockout
1
• Maintenance required
• Invalid unit configuration
Table 30. Tracer ZN520 diagnostics
Diagnostic Fan Other Outputs
(a)
Condensate overflow Off Valves Closed, Fresh air damper Closed, Electric heat Off, Baseboard heat Off
Low temperature detection Off Valves Open, Fresh air damper Closed, Electric heat Off, Baseboard heat Off
Low air flow - fan failure Off Valves Closed, Fresh air damper Closed, Electric heat Off, Baseboard heat Off
Space temperature failure Off Valves Closed, Fresh air damper Closed, Electric heat Off, Baseboard heat Off
Entering water temp failure On Valves Enabled
(b)
, Fresh air damper Enabled
(b)
, Electric heat Enabled
(b)
, Baseboard heat Off
Discharge air temp low limit Off Valves Open, Fresh air damper Closed, Electric heat Off, Baseboard heat Off
Discharge air temp failure Off Valves Closed, Fresh air damper Closed, Electric heat Off, Baseboard heat Off
Fresh air temp failure On Valves Enabled, Fresh air damper Minimum position
(c)
, Electric heat Enabled, Baseboard heat Enabled
Relative humidity failure On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled, Baseboard heat Enabled
Generic 4–20mA failure On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled, Baseboard heat Enabled
CO
2
Input failure On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled, Baseboard heat Enabled
Maintenance required On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled, Baseboard heat Enabled
Local fan mode failure On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled, Baseboard heat Enabled
Local setpoint failure On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled, Baseboard heat Enabled
Invalid unit configuration Off Valves Disabled, Fresh air damper Disabled, Electric heat Disabled, Baseboard heat Disabled
Normal—power up On Valves Enabled, Fresh air damper Enabled, Electric heat Enabled
(a) The generic binary output (TB4-1, TB4-2) state is unaffected by all unit diagnostics.
(b) When the entering water temperature is required but not present, the Tracer ZN520 controller generates a diagnostic to indicate the sensor loss condition.
The controller automatically clears the diagnostic once a valid entering water temperature value is present (non-latching diagnostic). When the entering
water temperature sensor fails, the controller prohibits all hydronic cooling operation, but allows the delivery of heat when heating is required. In the
Cool mode, all cooling is locked-out, but normal fan and outdoor air damper operation is permitted.
(c) When the outdoor air temperature sensor has failed or is not present, the Tracer ZN520 controller generates a diagnostic to indicate the sensor loss
condition. The controller automatically clears the diagnostic once a valid outdoor air temperature value is present (non-latching diagnostic). When the
outdoor air temperature sensor fails or is not present, the controller prohibits economizer operation.
1
Non-latching diagnostics automatically reset when the input is present and valid.
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