134
Accessory Control Components
In addition to the factory-installed options, the units can also
be equipped with several field-installed accessories that ex-
pand the control features of the unit. The following hardware
components can be used as accessories.
ROOM THERMOSTATS (48/50A2,A4,A6,A8 UNITS ONLY)
The ComfortLink controls support a conventional electro-me-
chanical or electronic thermostat that uses the Y1, Y2, W1,
W2, and G signals. The control also supports an additional in-
put for an occupied/unoccupied command that is available on
some new thermostats. The ComfortLink controls can be con-
figured to run with multiple stages of capacity which allows up
to 6 stages of capacity. Although the unit can be configured for
normal 2-stage control, it is recommended that the multi-stage
control be used. The room thermostat is connected to TB4.
SPACE SENSOR
The ComfortLink controls support the use of space temperature
sensors. The T55 and T56 sensors and CCN communicating T58
room sensor can be used. The T55 and T56 sensors are connected
to TB5 terminal 3, 4, and 5. The T58 sensor is connected to the
CCN connections on TB3. When a T55, T56, or T58 sensor is
used, the user must install the red jumpers from R to W1, and W2
on TB4 for the heat function to work correctly.
SPACE CO
2
SENSORS
The ComfortLink controls also support a CO
2
IAQ sensor that
can be located in the space for use in demand ventilation. The
sensor must be a 4 to 20 mA sensor and should be connected to
TB5 terminal 6 and 7. See Fig. 38 for sensor wiring.
ECONOMIZER HUMIDITY CHANGEOVER SENSORS
The ComfortLink controls support 5 different changeover
schemes for the economizer. These are:
• outdoor air dry bulb
• differential dry bulb
• outdoor air enthalpy curves
• differential enthalpy
• custom curves (a combination of an enthalpy/dewpoint
curve and a dry bulb curve).
The units are equipped as standard with an outside air and re-
turn air dry bulb sensor which supports the dry bulb change-
over methods. If the other methods are to be used, then a field-
installed humidity sensor must be installed for outdoor air en-
thalpy and customer curve control and two humidity sensors
must be installed for differential enthalpy. Installation holes are
pre-drilled and wire harnesses are installed in every unit for
connection of the humidity sensors. The ComfortLink controls
convert the measured humidity into enthalpy, dewpoint, and
the humidity changeover curves.
FIELD-INSTALLED MOTORMASTER CONTROL
For operation below 32°F when an economizer is not used, the
units can be equipped with a field installed accessory Motormas-
ter
®
control, which controls the speed of the stage 1 condenser
fans. The Motormaster control is a 3-phase inverter that controls
the speeds of the fans based on a pressure transducer connected to
the liquid line. On 48/50A020-035 units, one fan will be con-
trolled. On 48/50A036-060 units, two fans will be controlled. For
units equipped with an economizer, there should not be a need for
this control because the economizer can provide free cooling us-
ing outside air, which will be significantly lower in operating cost.
The accessory Motormaster V speed control is a completely self-
contained control and is not controlled by the unit’s ComfortLink
controller. On 48/50A051 and 060 units with 6 fan motors, the
Motormaster control configuration (M.M.) must be set to YES.
Fig. 38 — CO
2
and Space Temperature Sensor Wiring (33ZCT55CO2 and 33ZCT56CO2)
J6
TB4
1
2
3
4
5
6
7
1
2
3
4
5
6
7
TB5
UNIT CONTROL BOX
1
2
J3
J5
J4
B4
OVERRIDE
3
2
1
1
2
3
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