Unit protection strategies
CNT-SVX06B-EN 31
Unit protection strategies
The following strategies are initiated when specific conditions exist in
order to protect the unit or building from damage:
• Smart reset
• High/low pressure cutout
• Low-temperature protection
• Condensate overflow
• Filter-maintenance timer
• Fan off delay
Smart reset
The Tracer ZN511 will automatically restart a unit that is locked-out as a
result of a High/Low Pressure Cutout (BI4, BI5) diagnostic or a Low
Temp Detection Circuit 1 (AI1) or Low Temp Detection Circuit 2 (BI1)
diagnostic. Referred to as “smart reset,” this automatic restart will occur
30 minutes after the diagnostic occurs. If the unit is successfully
restarted, the diagnostic is cleared. If the unit undergoes another smart
reset diagnostic within a 24-hour period, the unit will be locked out until
it is manually reset. For more information on manual resetting, see “Man-
ual (latching) diagnostics” on page 66).
Low-temperature protection
See “AI1: Leaving water temperature” on page 20 for circuit 1, and “BI1:
Low-temperature detection (circuit 2)” on page 14 for circuit 2.
Condensate overflow
See “Condensate overflow” on page 31.
High/low pressure cutout
See “High/low pressure cutout” on page 31.
Filter-maintenance timer
The filter-maintenance timer tracks the amount of time (in hours) that
the fan is enabled. The Maintenance Required Timer Setpoint, configured
with the Rover service tool, is used to set the amount of time until main-
tenance (typically, a filter change) is needed. If the set point is configured
to zero, the filter-maintenance timer is disabled.
The controller compares the fan-run time to Maintenance Required Timer
Setpoint. Once the set point is reached, the controller generates a Mainte-
nance Required diagnostic. When the diagnostic is cleared, the controller
resets the filter-maintenance timer to zero, and the timer begins accumu-
lating fan-run time again.
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