Nortek FT4BE-K - Thermostat; Low Voltage Connections; CoreSense Diagnostics Module

6
G
RW2
C
E
O
Y
Thermostat
Green
Red
White
G
R
Black
O
Y1 IN
R
C
Air Handler
Heat Pump
(OD Section)
C
W
W2 OUT
W2 IN
Figure 4. Typical Thermostat Connections
Table 2. Thermostat Wire Gauge
Thermostat
Wire Gauge
Recommended T-Stat Wire
Unit to T-Stat (Length in FT)
2-Wire
(Heating)
5-Wire
(Heating/Cooling)
24 55 25
22 90 45
20 140 70
18 225 110
Thermostat / Low Voltage Connections
• Thermostatconnectionsshouldbemadeinaccordance
with the instructions supplied with the thermostat and
the indoor equipment. A typical installation with a heat
pump thermostat and air handler is shown in Figure 4.
• Theoutdoorunitisdesignedtooperatefroma24VAC
Class II control circuit. The control circuit wiring must
comply with the current provisions of the NEC (ANSI/
NFPA 70) and with applicable local codes having
jurisdiction.
• Thelowvoltagewiresmustbeproperlyconnectedto
the units low voltage terminal block. Recommended
wire gauge and wire lengths for typical thermostat
connections are listed in Table 2.
• The thermostat should be mounted about 5 feet
above the floor on an inside wall. DO NOT install the
thermostat on an outside wall or any other location
where its operation may be adversely affected by radiant
heat from fireplaces, sunlight, or lighting fixtures, and
convective heat from warm air registers or electrical
appliances. Refer to the thermostat manufacturer’s
instruction sheet for detailed mounting and installation
information.
CoreSense
TM
Diagnostics Module
(Select Models Only)
The CoreSense
TM
Diagnostics Module (Figure 5, page
7) is a breakthrough innovation for troubleshooting heat
pump and air conditioning system failures. The module
installs easily in the electrical box of the outdoor unit
near the compressor contactor.By using the compressor
as a sensor, CoreSense Diagnostics helps the service
technician more accurately troubleshoot system and
compressor fault conditions.
A flashing LED indicator communicates the ALERT code
and a diagnostic key is also imprinted on the side of the
module to quickly direct the technician to the root cause
of a problem. Alert identification codes are also listed in
Table 3 (page 7).
Compressor Protection
The CoreSense
TM
Diagnostics module utilizes proprietary
algorithms to protect the compressor and system from
repeated trips of system pressure controls and the
compressor internal overload. The protection terminal
of the module should be wired in series with the system
low pressure and high pressure cutouts, as well as the
compressor contactor. When the module detects a series
of trips as described below, it will activate a lockout feature
that opens the normally closed protection contacts in
the module, thereby cutting power to the contactor and
shutting off the compressor.
COPPER WIRE SIZE — AWG
(1% Voltage Drop)
Supply Wire Length-Feet
Supply Circuit
Ampacity
200 150 100 50
6 8 10 14 15
4 6 8 12 20
4 6 8 10 25
4 4 6 10 30
3 4 6 8 35
3 4 6 8 40
2 3 4 6 45
2 3 4 6 50
2 3 4 6 55
1 2 3 4 60
Wire Size based on N.E.C. for 60° type copper conductors.
Table 1. Copper Wire Size