149
Table 117 — Thermistors and Unit Operation Control Pressure Transducers
LEGEND
FAN STATUS SWITCH
The units can be equipped with an optional fan status switch
that will monitor the pressure rise across the indoor fans.
RETURN AIR CO
2
SENSOR
The unit can be equipped with a return air IAQ CO
2
sensor that
is used for the demand-controlled ventilation. The sensor is lo-
cated in the return air section and can be accessed from the fil-
ter access door.
BOARD ADDRESSES
Each board in the system has an address. The MBB has a de-
fault address of 1 but it does have an instance jumper that
should be set to 1, as shown in Fig. 30. For the other boards in
the system, there is a 4-dip switch header on each board that
should be set as shown below.
0 = On; 1 = Off
PHASE LOSS PROTECTION MONITOR OPTION (PMO)
If all 3 phases of electrical supply are relatively equal and in
proper sequence, the normally open contacts (Y/Y-OUT) will
close when 24 volts are applied between C and Y terminals. If
the phases are out of sequence, or if one is missing, the con-
tacts will never close. If a phase is lost while the phase monitor
is energized, the contacts will open immediately and will re-
main open until the error is corrected.
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
ComfortLink controls support a conventional electro-mechanical
or electronic thermostat that uses the Y1, Y2, W1, W2, and G sig-
nals. The control also supports an additional input for an occupied/
unoccupied command that is available on some new thermostats.
The ComfortLink controls can be configured to run with up to 6
stages of capacity. The room thermostat is connected to TB201.
ComfortLink controls also support the use of space temperature
sensors and can be used with the T55 and T56 sensors. The con-
trols can also be used with CCN communicating T58 room sensor.
The T55 and T56 sensors are connected to TB201 terminals 1, 2,
and 3. The T58 sensor is connected to the CCN connections on
COMM board. Whenever a unit equipped with heat is operated
without a thermostat, the user must install the red jumpers from R
to W1, and W2 on TB201 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
TB201 terminals 7 and 8.
ECONOMIZER HUMIDITY CHANGEOVER SENSORS
The ComfortLink controls support 5 different changeover sys-
tems for the economizer. These are:
• Outdoor enthalpy switch
• Outdoor air dry bulb
SENSOR DESCRIPTION AND LOCATION PART NO.
Thermistors
CCT
Cooling Coil Thermistor input. Provided with factory-option hydronic heat. Located on face of the hydronic
heating coil. Consists of 4 thermistors wired into a 2x2 array.
HH79NZ039 (4)
LST
Limit Switch Thermistor. Provided with Staged Gas Control option. Located in the heating
compartment.
HH79NZ034
OAT Outside Air Thermistor. Located in top of the return plenum, attached to roof pole. HH79NZ039
RAT
Return Air Thermistor.
Without Economizer: Located on left side base rail in the return plenum.
With Economizer: Located on left side face of return damper section in the return plenum.
HH79NZ039
SAT
Supply Air Thermistor. Located in the Supply Fan section, on left side of the fan housing.
(May be relocated or replaced when unit is used with CCN Linkage systems; see page 66.)
HH79NZ039
LAT 1,2,3
Leaving Air Thermistors, provided with Staged Heat Control option. Shipped in the control box.
Installer must pull out and mount in the supply duct.
HH79NZ034 (3)
Control Pressure Transducers
BP
Building Pressure. Provided with Modulating Power Exhaust, High-Capacity Power Exhaust
and Return Fan options. Located in the auxiliary control box (left-hand side of unit near return plenum).
HK05ZG018
DPT-A Discharge Pressure (refrigerant), Circuit A. HK05ZZ001
DPT-B Discharge Pressure (refrigerant), Circuit B. HK05ZZ001
SPT-A Suction Pressure (refrigerant), Circuit A. HK05SZ003
SPT-B Suction Pressure (refrigerant), Circuit B. HK05SZ003
DSP
Duct Static Pressure. Provided with VAV models equipped with VFD or Inlet Guide Vane options. Located
in the auxiliary control box (right-hand side of unit near return plenum).
HK05ZG010
FT_SF
Supply Air Cfm (velocity pressure). Provided with factory-option return fan system
(sizes 075-100 only). Located in the supply fan compartment, on right side, on vertical post.
HK05ZG015
FT_RF
Return Air Cfm (velocity pressure). Provided with factory-option return fan system
(sizes 075-100 only). Located in auxiliary control box (right-hand side, filter access panel).
HK05ZG07
Outside Air CFM
Control
Outside Air Cfm Monitor (velocity pressure). Provided with the Outside Air Cfm Control option. Located in
auxiliary control box (right-hand side, filter access panel).
50ZZ400290 (030-070)
50ZZ400289 (075-100)
DTT
Digital Scroll Discharge Temperature Thermistor. Provided with digital scroll compressor option. Located
on discharge line.
HH79EZ003
RGTA
Circuit A Return Gas Thermistor. Provided with MLV option. Located in suction line well. HH79NZ016 (030-060)
HH79NZ020 (070, 075)
HH79NZ014 (090, 100)
MLV — Minimum Load Valve
VAV — Variable Air Volume
VFD — Variable Frequency Drive
BOARD SW1 SW2 SW3 SW4
RXB0000
EXB1000
SCB0000
CEM0000
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