Freeze Avoidance; Freeze Protection (Discharge Air Temperature Low Limit) - Trane BCHE Installation, Operation And Maintenance Manual

accumulating fan run time again. The diagnostics can be
cleared and the filter timer reset by temporarily overriding
the Filter Timer Reset Request on the Binary Status
page or by using the reset button on the Alarms page in
®
Tracer TU.

Freeze Avoidance

Freeze avoidance is used for low ambient temperature
protection. It is initiated only when the fan is OFF. The
controller enters the freeze avoidance mode when the
outdoor air temperature is below the freeze avoidance
setpoint (configurable using the Tracer® TU service tool).
The controller disables freeze avoidance when the outdoor
air temperature rises 3°F (1.7°C) above the freeze
avoidance setpoint.
The following occurs when the controller is in freeze
avoidance mode:
• Valves are driven open to allow water to flow through
the coil
• Fan is OFF
• Economizing is disabled
BCX-SVX002A-EN
• The outdoor/return air damper is closed
• DX cooling is OFF
• Electric heat stages are OFF
Freeze Protection (Discharge Air
Temperature Low Limit)
The controller monitors the discharge air temperature with
a 10 kΩ thermistor wired to AI4. The freeze protection
operation is initiated whenever the discharge air
temperature falls below the discharge air temperature low
limit. The discharge air temperature low limit is configurable
using the Tracer® TU service tool. During freeze
protection, the controller increases the heating capacity or
decreases the cooling capacity in order to raise the
discharge air temperature above the low limit. If the
discharge air temperature remains below the low limit for 3
minutes, the controller generates a Discharge Air Temp
Limit diagnostic.
Freeze protection will also perform a smart reset. Refer to
"Smart Reset," p. 112.
Start-Up
113