151
Table 108 — Thermistors and Unit Operation Control Pressure Transducers
LEGEND
SPACE CO
2
SENSORS — The ComfortLink controls also
support a CO2 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 SEN-
SORS — The ComfortLink controls support 5 different
changeover systems for the economizer. These are:
• Outdoor enthalpy switch
• 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 outdoor air en-
thalpy control. Outside air and return air dry bulb sensors
which support the dry bulb changeover method are also sup-
plied as standard. If the other methods are to be used, then a
field-installed humidity sensor must be installed for outdoor air
enthalpy 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
have the capability to convert the measured humidity and dry
bulb temperature into enthalpy.
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 com-
partment.
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 71.)
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)
ST-A1
ST-A2
Suction Thermistor, Circuits A1 and A2. Located in well in evaporator outlet. A1 is top coil, A2 is
bottom coil
HH79NZ014 (2)
ST-B1
ST-B2
Suction Thermistor, Circuits B1 and B2. Located in well in evaporator outlet. B1 is top coil, B2 is
bottom coil
HH79NZ014 (2)
LT_A Liquid Line Thermistor, Circuit A. Located in evaporator section on inlet to EXV A1 and A2. HH79EZ003
LT_B Liquid Line Thermistor, Circuit B. Located in evaporator section on inlet to EXV B1 and B2. HH79EZ003
Control Pressure Transducers
BP
Building Pressure. Provided with Power Exhaust and Return Fan options. Located in the control
box.
HK05ZG022
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 control box.
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).
48NG501985 (75-105)
48NG501986 (120-150)
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. HH79NZ014
FT_SF
Supply Air CFM - Sensor bars are mounted on inlet to fan. Transducer is mounted in Control Box
and is fan dependent.
HK05ZG019 (Low Fan)
HK05ZG023 (High Fan)
FT_PE
Power Exhaust CFM - Sensor bars are mounted on inlet to fan. Transducer is mounted in Control
Box and is fan dependent.
HK05ZG019 (Low Fan)
HK05ZG023 (High Fan)
FT_RF
Return Air CFM - Sensor bars are mounted on inlet to fan. Transducer is mounted in Control Box
and is fan dependent.
HK05ZG020 (Low Fan)
HK05ZG023 (High Fan)
OACFM
Outside Air CFM - Sensor bars are mounted on air intake, same side as Control Box. Transducer
is mounted in Control Box and is Unit size dependent.
48NG501985 (75 - 105)
48NG501986 (120 - 150)
MFDP
Filter Pressure Sensor - Return (+24 VDC, 4 20 mA loop power). Transducer is mounted in Con-
trol Box.
HK05ZG019
PFDP
Filter Pressure Sensor - Return (+24 VDC, 4 20 mA loop power). Transducer is mounted in Con-
trol Box.
HK06WC035
CCN — Carrier Comfort Network
EXV — Expansion Valve Control Board
VAV — Var iable Air Volume
VFD — Variable Frequency Drive
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