Ambient Compensation; Heating Mode; Cooling Mode; Dual Mode - EngA C-TRAC3 Installation, Operation And Maintenance Manual

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C-TRAC3

Ambient Compensation

Makeup air equipment normally uses a 2 position damper actuator. Equipment can be ordered with an
Ambient Compensation Package. Among other things, this package uses a modulating outside air damper
actuator. The modulating economizer output (ED) will control the actuator and vary the output signal
depending on the ambient temperature. As the ambient temperature falls, the output will decrease
proportionally, adding static pressure drop across the dampers and effectively reducing the outside air
volume. This compensates for the thermal expansion of the air as it passes over the heat exchanger.

HEATING MODE

Heating is allowed to operate if terminal HS is powered (24Vac). The heating is only activated when the C-
TRAC3 is in heat or dual mode. The C-TRAC3 has a set of contacts (terminals HE1 and HE2) that will close
to enable a heating source, as well as a modulating (0-10Vdc typically) output from terminal HD to control
an independent heating controller, SCR, or water/steam valve. Typically this output will drive one of the
Engineered Air heating controllers (G-TRAC, DJM, H-TRAC etc). Refer to the appropriate manual for
additional information on these controls.

COOLING MODE

Cooling mode is allowed if terminal A is powered (24Vac) and the ambient temperature exceeds the
minimum, pre-programmed low ambient setpoint. The cooling is only activated when the C-TRAC3 is in
cool or dual mode. The C-TRAC3 has 5 output contacts (1 to 5) to enable mechanical cooling stages.
Additionally, a modulating (0-10Vdc typical) output is available from terminal CD for control of a
modulating style of compressor or cooling valve actuator.
Terminal CF is an ambient based cooling output (24Vac). If the first cooling stage is enabled, and the
ambient temperature is above the pre-programmed setpoint, this contact will close. Typical applications
for this would be for an ambient based condenser fan or compressor.
Compressor inter-stage, and minimum on/off times range from 4 to 8 minutes depending on operating
conditions. When the C-TRAC3 first enters cooling mode the first compressor minimum delay is 2 ½
minutes, with the second compressor capable of starting 20 seconds later. These short compressor start
times occur only once whenever the C-TRAC3 initially enters the cooling mode.
Terminal AMB is wired to an externally mounted ambient sensor (Engineered Air TE6000-EA3). The
C-TRAC3 uses this sensor to perform multiple functions, such as low ambient compressor lockout, high
ambient set back, and mode control.

DUAL MODE

Dual control mode allows the cooling or economizer to operate at the same time as the heating. These
are for dehumidification and multi-zone equipment applications.
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