Outdoor Air Damper Operation - Trane LPC Install And Operation Instructions

opens the heating valve and uses the
heat face-and-bypass damper to
modulate heating capacity to maintain
the desired discharge air temperature.
During diagnostic and fan Off conditions,
when the controller shuts down unit
operation, the face-and-bypass damper is
in the full bypass position. During freeze
avoidance operation or a Low Temp
Detect diagnostic, the face-and-bypass
damper is driven to full face.

Outdoor air damper operation

This sequence applies to both space
temperature control and discharge air
temperature control. The controller
operates the modulating outdoor air
damper according to effective occupancy,
outdoor air temperature (communicated
or hardwired sensor), space
temperature, effective space
temperature setpoint, discharge air
temperature, and discharge air
temperature setpoint. Default minimum
damper positions are provided and can
be changed using the Rover service tool
for occupied and occupied standby
ventilation.
The controller can also receive a commu-
nicated outdoor air damper minimum
position setpoint. A communicated
minimum position setpoint has priority
over all configured minimum position
setpoints. When a communicated
minimum position setpoint is not present,
the controller uses the configured
minimum setpoints (see Table O-SO-8).
During occupied modes, the damper
remains at a minimum damper position,
whether it is configured or
communicated.
Mixed-air temperature control
The Tracer AH540/541 controller provides
minimum ventilation requirements
according to the effective occupancy
mode. Ventilation requirements are
maintained by mixed-air temperature
control depending on
available heating and cooling sources,
unit configuration, and mixed-air
temperature control type (configurable).
Low mixed-air temperatures can be a
concern for units with hydronic heating
and cooling.
78
Operation
Table O-SO-7 . Face-and-bypass damper operation based upon outdoor air temperature
Table O-SO-8. Determining the outdoor air damper minimum position setpoint
sequence of
operation
LPC-SVX01C-EN