Unit protection strategies
CNT-SVX06B-EN 55
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
Smart reset
The Tracer ZN511 will automatically restart a unit that is locked-out as a
result of a Low Temp Detection Circuit 1 (BI1) diagnostic. Referred to as
“smart reset,” this automatic restart will occur 30 minutes after the diag-
nostic 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 “Manual (latching) diagnos-
tics” on page 66).
Low-temperature protection
See “BI1: Low-temperature detection” on page 34.
Condensate overflow
See “BI2: Condensate overflow” on page 34.
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.
Fan off delay
After heating has been controlled off, the Tracer ZN511 automatically
keeps the fan energized for an additional 30 seconds. The purpose of this
feature is to remove residual heat from the heating source.
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