MegaControls NT10 Series User manual

Issue Date March 1, 2018
NT10 Series
RS-485 Modbus RTU Networking Room Thermostats for Fan Coil Units
support up to 32 NT10 Series
Modbus RTU devices. The BMGE
gateway spontaneously detects the
presence of slaves that go online
in its NET 1 and NET 2 networks.
The NT10 Series thermostats
cover a wide range of fan coil
applications, including 2 and 4-pipe
fan coils and direct connection to 3
-speed fans. Temperature sensing
can be from a built-in room sensor
or a remote sensor.
A fan-speed control touch key
allows control of a 3-speed fan.
The speed control key has 4
positions: “Hi-Med-Low-Auto”. In
the “Hi”, “Med” or “low” position,
the fan runs continuously at the
selected speed. In the “Auto”
mode, the fan speed is
temperature dependent and
controlled automatically at 2 K
differential increments from low to
high speed.
Ordering
To order, specify complete model
numbers.
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Copyright © Mega Controls Limited
Features
■ Ultra slim wall-mount unit to match
any decor
■ Supports standalone operation on RS
-485 communication failure. A power
reset must be carried out on
thermostat before this can take place.
■ Fan coil application database pre-
loaded
■ Large easy-to-read Liquid Crystal
Display (LCD), with LED backlight
■ A stylish bi-directional rotating dial
and two compact touch keys to
provide ease of operation
■ Choice of constant display of ambient
temperature or temperature set point
value
■ Output relays employed for direct
connection of valve actuators and 3-
speed fan
■ Configurable operating parameters
■ Choice of ºC or ºF temperature
display via parameter setup menu
■ 2-wire on-off, 3-wire floating and 0-10
VDC output models available
■ Adjustable proportional band for 3-
wire floating and modulating models
■ Adjustable integral time for
modulating models
■ Choice of valve stroke time for 3-wire
floating output models
■ Field adjustable high and low
occupied set point limit settings
■ Field adjustable cooling and heating
unoccupied set point values
(applicable to some models only)
■ Choice to retain last entered settings
on power resumption
■ Dual-output on-off and 0-10 VDC
models with auto cooling/heating
changeover (deadband operation)
and manual override
■ Choice of operating sequence for dual
-output models
■ Adjustable 1 to 5 K deadband for dual
-output models
■ Unoccupied mode capability with field
adjustable cooling and heating set
points, , not available to “1M”, 1AM”
and “1FM” models.
■ Choice of unoccupied mode activation
in operating mode only or in both
standby and operating modes
■ Window contact closure to shut down the
FCU and lock out all thermostat functions
■ Provides one additional digital input
for function such as remote night
setback, service/filter alarm or motion
detection
■ Choice of fan action in unoccupied
mode
■ Choice of auto fan action in heating
mode
■ Field recalibration capability of
measured temperature
■ Continuous or auto fan operation
■ External and seasonal changeover
temperature sensor capability
■ Optional infra-red remote control unit
■ Optional special faceplate color
available on request
General
The NT10 Series RS-485 networking
room thermostats use the communication
technologies of Modbus RTU
communication protocol to monitor and
supervise fan coil units in the heating,
ventilating and air-conditioning industry,
and employ a simple master/slave
protocol. All NT10 Series thermostats are
slaves in this protocol, and can be under
the control of a Mega Controls BACnet
gateway, either BMG or BMGE Series,
called the master. The BMGs and
BMGEs are native BACnet MS/TP
devices and communicate using the
BACnet MS/TP or BACnet-over-Ethernet
protocol. The master can also be a
Modbus network supervisor.
The master and all slaves are daisy-
chained through a RS-485 Modbus RTU
network. The maximum number of NT10
slaves in a Modbus RTU network is 32.
Each BMG has 2 addresses. Net 2
address is always 0 which is the address
of the Modbus RTU network. Net 1
address is the MAC address of the
BACnet MS/TP network which is also set
up for a maximum of 32 devices in a
trunk cable length not exceeding 1000 m.
The BMG gateway spontaneously
detects the presence of slaves that go
online in its NET 2 network.
If more than 32 BMGs are needed in the
system, an additional BACnet system
device is required for the second BACnet
MS/TP network.
Each BMGE gateway is available with
two RS-485 networks. Each network can

Specifications
Product Model Numbers See Fig.1: NT10 Series Model Number Selection Guide
Power Requirements 110-230 V, +10% and -15%, 50/60 Hz
Operating temperature differential
(for 2-wire on-off models)
Fixed at 1 K for both cooling and heating modes
Temperature Display Range 5-35ºC in 0.5 K increments: accuracy ±1 K (41-95ºF in 0.5 R increments, accuracy ±1 R)
Temperature Set Point Range 5-35ºC in 0.5 K increments, initial factory setting at 22ºC (41-95ºF in 0.5 R increments)
Offset adjustment of temperature
indication (field recalibration)
+2, +1, 0, -1 and -2 K (+2, +1, 0, -1 and -2 R) throughout the range, factory setting 0
Deadband of dual-output models Adjustable 1 to 5 K(2 to 10 R) between cooling Mode and heating Mode, factory set at 3 K(6 R)
Valve stroke time for 3-wire floating
models
Accumulatively 10 to 240 s maximum in one direction in steps of 10 s,
Factory setting 180 s
Proportional band for PI control Adjustable 1 to 10 K (1-10 R) in 1 K (1 R) increments, factory setting 5 K (5 R)
Integral time for PI control Adjustable 0 to 30 minutes in 1 minute increments, factory setting 15 minutes. Setting = 0
means integral time being turned off.
Auto fan temperature differential At 2 K (2 R) increments. At >0 K, fan is on low speed in cooling mode and fan status in heating
mode depends on choice of auto fan action.
Sensing Element NTC thermistor, 10 kΩ@25ºC; accuracy ±0.5 K@25ºC
Unoccupied Mode Input signal from external voltage-free contact
Always runs at “Low” fan when in operation
Unoccupied temperature set point
range (not applicable to “1M” models)
Field adjustable 5-35ºC (41-95ºF) in 1 K (1 R) increments separately for cooling and heating;
Factory settings: 16ºC (61ºF) for heating and 26ºC (79ºF) for cooling
Digital Outputs For Direct Connection of Valve Actuators (110-230 VAC)
1 Relay Output for 2-Pipe Models
2 Relay Outputs for 4-Pipe Models
For Direct Connection to 3-speed Fans (110-230 VAC)
3 Relay Outputs
RS-485 Communication Speed Baud rate fixed at 19200 bps
Device MAC Addressing 01-32 via parameter setup menu, factory default setting 255 (displays as FF on thermostat
screen)
Proprietary FClink Network and
Modbus RTU Network Guideline
Maximum 32 devices and maximum 1,000 m cable length
Enclosure Material: Self-extinguishing, molded ABS
Finish: Off white housing and dark grey faceplate
Electrical ratings Valve output relays 110-230 V, 5 A resistive, 2 A inductive, 50/60 Hz
Fan output relays
For on-off and floating models 110-230 V, 5 A resistive, 2 A inductive, 50/60 Hz
For 0-10 VDC models 110-230 V, 5 A resistive, 2 A inductive, 50/60 Hz
Total rating 110 -230 V, 5 A maximum, 50/60 Hz
Ambient/Storage Temperature Limits 0 to 55ºC/-30 to 50ºC , 10 to 90% RH Non-condensing
Connectors Non-removable line-voltage terminal blocks and removable low-voltage wire plugs
Power wires Wire size 1 mm2 or 18 AWG solid copper recommended
RS-485 Communication Wires 22 or 24 AWG twisted shielded pair double-insulated cable
Sensor wires 22 AWG twisted shielded pair double-insulated cable
Accessories and options See Figure 8: Optional Accessories
Agency approval CE Mark compliant to EMC and Low Voltage Directives
Shipping weight 0.78 kg (1.7 lb)
Dimensions See Figure 4: Dimensions in mm
Binary input 2 binary inputs for external voltage-free contacts
24 VAC valve output triac Permissible current 0.3 A, 50/60 Hz
The performance specifications above are nominal and subject to tolerances and application variables of generally acceptable industry standards.
The manufacturer shall not be liable for damages resulting from misapplication or misuse of its products.
2 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin

Figure 1: NT10 Series Model Number Selection Guide
NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 3
NT10 Series RS-485 Networking Room Thermostats Model Number Selection Guide (Complete Sets)
NT1 0 – 1M R
Product Type Power Supply Separator Control Type Options
NT1 = NT10 Series 0 = 110-230 VAC 1 = Single 2-wire on-off output, R = with infra-red
RS-485 cool only or heat only Receiver for RCU-1
networking room 2* = 230 VAC 1M = Single 2-wire on-off output, B = without buzzer for
thermostats + 24 VAC manual cool/heat changeover key touch sounding
3* = 120 VAC 1A = Single 0-10 VDC output, W = with white color
+ 24 VAC cool only or heat only faceplate
1AM = Single 0-10 VDC output, E = with energy metering
* Suitable for line-voltage manual cool/heat changeover capability
fan control and 24 VAC 1F = Single 3-wire floating output,
2-wire on-off or 3-wire cool only or heat only
floating valve control 1FM = Single 3-wire floating output,
manual cool/heat changeover
2 = Dual 2-wire on-off outputs,
manual or auto cool/heat changeover
2A = Dual 0-10 VDC outputs,
manual or auto cool/heat changeover
2A = Dual 3-wire floating outputs,
manual or auto cool/heat changeover
2AH = Dual outputs, 0-10 VDC cooling
+ line-voltage on-off heating,
manual or auto cool/heat changeover
Networking Control Unit Model Number Selection Guide
NCU1 1 A M – R
Product Type Number of Outputs Control Type Seasonal
Changeover
Separator Options
NCU1 = Network Control Units 1 = Single output Nil = 2-wire on-off Nil = Auto by Nil = No option
For NT10 Series 2 = Dual outputs F = 3-wire floating external R = with IR receiver
A = 0-10 VDC sensor for RCU-1
AH = 0-10 VDC + on-off M = Manual B = without buzzer for
key touch sounding
W = with all-white NCU
enclosure
E = with energy
metering
Power Supply Unit Model Number Selection Guide
NPSU1 0 – 1 F
Product Type Power Supply Separator Number of Outputs Control Type
PSU1 = Power Supply Units 0 = 100-230 VAC 1 = Single output Nil = 2-wire on/off
for NT10 Series 2 = Dual outputs F = 3-wire floating
2 = 230 VAC + 24 VAC* A = 0-10 VDC
3 = 120 VAC + 24 VAC* AH = 0-10 VDC + on-off
* Suitable for line-voltage
fan control and 24 VAC
2-wire on-off or 3-wire
floating valve control

4 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin
Figure 3: Dimensions in mm
Remote Control Unit Display Control Unit
Power Control Unit
Model
Numbers
Outputs Applications Cooling/Heating
Mode
External
Seasonal
Changeover
System
Modes
Fan Control Unoccupied
Mode
NT10-1 Single Line-Voltage
2-Wire On-Off
Cooling Only
or Heating Only
Auto Only Yes Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-1M Single Line-Voltage
2-Wire On-Off
Cooling/Heating Manual Only No Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-1F Single Line-Voltage
3-Wire Floating
Cooling Only
or Heating Only
Auto Only Yes Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-1FM Single Line-Voltage
3-Wire Floating
Cooling/Heating Manual Only No Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-1A Single
0-10 VDC
Cooling Only
or Heating Only
Auto Only Yes Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-1AM Single
0-10 VDC
Cooling/Heating Manual Only No Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-2 Dual
2-Wire On-Off
Cooling and Heating Manual or Auto No Cool-Heat-Auto-Fan
Only-Off or Auto-Off
Hi-Med-Low-Auto Yes
NT10-2A Dual
0-10 VDC
Cooling and Heating Manual or Auto No Cool-Heat-Auto-Fan
Only-Off or Auto-Off
Hi-Med-Low-Auto Yes
NT12-1 Single 24 VAC
2-Wire On-Off
Cooling Only
or Heating Only
Auto Only Yes Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT12-2 Dual 24 VAC
2-Wire On-Off
Cooling and Heating Manual or Auto No Cool-Heat-Auto-Fan
Only-Off or Auto-Off
Hi-Med-Low-Auto Yes
NT12-2F Dual 24 VAC
3-Wire Floating
Cooling and Heating Manual or Auto No Cool-Heat-Auto-Fan
Only-Off or Auto-Off
Hi-Med-Low-Auto Yes
NT12-1F Single 24 VAC
3-Wire Floating
Cooling Only
or Heating Only
Auto Only Yes Cool or Heat-Fan
Only-Off
Hi-Med-Low-Auto Yes
NT10-2F Dual Line-Voltage
3-Wire Floating
Cooling and Heating Manual or Auto No Cool-Heat-Auto-Fan
Only-Off or Auto-Off
Hi-Med-Low-Auto Yes
NT10-2AH Dual Outputs,
0-10 VDC + Line-
Voltage On-Off
Cooling and Heating Manual or Auto No Cool-Heat-Auto-Fan
Only-Off or Auto-Off
Hi-Med-Low-Auto Yes
Figure 2: NT10 Series Application Guide

USER OPERATING MODE
■ LCD shows ambient temperature constantly except when set point adjustment is being made.
■ Press the switch key Ф to enter into the desired operating mode: Cool-Heat-Auto-Fan Only-Off, etc.
■ Press the fan key  to change the fan speed mode: High-Med-Low-Auto.
■ Increase or decrease temperature set point in 0.5 K increments by rotating the adjustment dial clockwise or counter-clockwise. When
the dial is rotated, the LCD shows the existing set point setting.
ENERGY SAVING MODE
■ When the energy saving contact closes, it will override the operating mode and operate the thermostat in energy saving mode despite
the thermostat being in operating or standby mode.
■ In energy saving mode, the factory-set temperature cut-in points are 26°C for cooling and 16°C for heating. Meanwhile, the operation
of all operating keys is locked out until the energy saving contact opens.
■ During energy saving mode, the default fan speed is set at “low” when pre-set cut-in temperature is reached, or otherwise the fan
output is always “off”.
■ Energy saving mode can be activated in the following manner when the energy saving contact closes:
For 2-pipe models with auto seasonal changeover, the energy saving cooling or heating mode is determined by the status of the SR2
seasonal changeover sensor and the valve output is activated according to the measured temperature.
For 2-pipe models with manual seasonal changeover, while in energy saving mode, the valve output is never activated and the fan
always runs at low speed.
For 4-pipe models, the energy saving cooling or heating mode is always determined by the measured temperature and valve output is
also activated according to the measured temperature.
Energy saving mode activation in operating mode only or in both standby and operating mode will be determined by activation setting
in setup menu. Low fan will run according to fan action setting in setup menu.
When energy saving mode is activated, all keys are locked out and no settings can be entered.
WINDOW MODE
■ When Window contact closes, it will override the operating mode and operate the thermostat in off mode despite the thermostat being
in operating or standby mode. Meanwhile, all operating keys are locked out until the window contact opens.
PARAMETER SETUP MODE
■ The thermostat allows authorized service agent to change a number of operating parameters in the field. For details, refer to the
parameters setup manual.
ERROR REPORTING
■ All valve and fan outputs will be shut down when error is reported.
Operation Notes
Figure 6: Network Control Unit and LCD Layout
NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 5
Figure 5: Optional Accessories
Description Part Number
Remote control unit RCU-1
Probe temperature sensor TE10-1
Duct temperature sensor TE10-2
With infra-red receiver capability NT10-xxR
Without buzzer capability NT10-xxB
With white color faceplate NT10-xxW
With energy metering capability NT10-xxE
Figure 4: NCU Mounting Details
Mounting of Network Control Unit
The NT10 network control unit can be flush mounted or secured to a
standard European 75 x 75 x 35 mm electrical box. See Fig. 2: Mounting
Details. Two M3.5 mounting screws for Network Control Units only are
included.

Figure 7: Network Configuration
With BMG BACnet MSTP Gateway
NT10 NT10 NT10 NT10
BMG
(Master)
BMG
(Master)
To BACnet MS/TP
Network Supervisor
Slaves
With BMGE BACnet-over-Ethernet Gateway
NT10 NT10 NT10 NT10
BMGE
(Master)
NT10 NT10 NT10 NT10
Slaves
Slaves
Modbus RTU Network Notes:
1. Ensure the recommended balanced
cable is used.
2. Ensure the cable is installed as a daisy
chain from one device to the next
(1,000 m maximum) and the shield is
grounded at one single point of the
network only.
3. Ensure a terminator is installed on each
end of each Modbus RTU network.
4. The maximum nodes per Modbus RTU
network is 32
BACnet MS/TP Network Notes:
1. Ensure the recommended balanced
cable is used.
2. Ensure the cable is installed as a daisy
chain from one device to the next
(1,000 m maximum) and the shield is
grounded at one single point of the
network only.
3. Ensure a MS/TP terminator is installed
on each end of a MS/TP network.
4. The maximum nodes per MS/TP
network is 32.
6 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin

Item Description
Cabling It is recommended to use networking cabling that matches the following specifications:
 Balanced 100 to 120 ohms nominal impedance, 22 or 24 AWG Twisted Shielded Pair (TSP) Cable
 Nominal capacitance of 52 pF/m or lower
 Nominal velocity of propagation of 66% or higher
 Terminating the shield to ground at one end only for each isolated segment will prevent ground loops in the
shield and drain RF energy to ground. Grounding at the BACnet router or controller is preferred.
Topology Ensure the BACnet MS/TP or Modbus RTU network cable is installed as a daisy chain from one device to the
next.
Maximum Nodes The maximum number of devices is 32 per BACnet MS/TP or Modbus RTU network.
Terminator A terminator of 120-ohm impedance must be installed at each end of each BACnet MS/TP or Modbus RTU
network segment, or two per network. Ensure that this requirement is not overlooked in laying out the network
architecture and when ordering product.
Repeater A repeater is not necessary unless the network is extended beyond 1,000 m.
Cable Shielding Use a shielded, twisted pair cable for communications. Never directly ground wire in more than one point on
the shield. Doing so can induce large currents and result in communication problem.
Step-down Transformer A separate isolated double-wound transformer is recommended for supplying 24 VAC power to each BMG or
BMGE. If and when the same transformer is shared with other devices, observe the polarities of the power
supply of all devices including the BMG or BMGE.
Network, Cabling & Step-down Transformer Requirements
To ensure network stability and reliable communications, particularly at high speeds on a BACnet MS/TP or Modbus RTU
network for a number of devices, it is imperative that the following network, cabling step-down transformer requirements
are adhered to:
NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 7
The networking thermostats consist of two basic units: the Net-
work Control Unit and the Power Supply Unit. While all line-
voltage wiring is terminated at the Power Supply Unit, all connec-
tions between Network Control Unit and Power Supply Unit are
of low-voltage signaling wires.
Wiring and Application Notes
■ Cut jumper JP1 if external sensor is wired to SR1 and GND.
Run the wiring away from any electrical motors or power wir-
ing. Failure to do so may result in poor thermostat perfor-
mance due to electrical noise.
■ 22 AWG twisted shielded pair double-insulated cable is rec-
ommended as remote sensor wiring and its length must not
exceed 25 m.
■ Do not bundle and run power wiring and remote sensor wiring
in the same conduit.
■ Connecting wires between Network Control Unit and Power
Supply Unit must not exceed 15 m.
■ Seasonal changeover sensor or switch is only applicable to heat
only or cool only 2-pipe model only.
■ The seasonal changeover sensor should be wrapped around the
supply water pipe when associated with a water system. When
the changeover sensor temperature exceeds 30 ºC, the thermo-
stat enters into heating mode.
■ The thermostat outputs are designed for controlling zone valves.
If used for controlling electric heaters, external contactors must
be used.
■ Window contact closure at Terminals WIN and GND will shut
down the FCU and lock out all thermostat functions.
■ Contact closure at Terminals OCU and GND will activate the
energy saving mode.
Figure 8: Wiring Diagrams and Application Notes

8 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin
Wiring Diagram for Line-Voltage Fan and Line-Voltage 2-Wire On-Off Valve Outputs
Piping Notes:
1. On a single-output unit, V1 can be a 2-wire cooling or heating valve.
2. On a dual-output unit, V1 must be a 2-wire cooling valve and V2 a 2-wire heating valve.
3. Hidden-line wiring for Terminals V2 and 6 are applicable to dual-output models only.
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Inter-connecting wires: Cat 5e twisted 6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable

Wiring Diagram for Line-Voltage Fan and 24 VAC 2-Wire On-Off Valve Outputs
Piping Notes:
1. On a single-output unit, V1 can be a 2-wire cooling or heating valve.
2. On a dual-output unit, V1 must be a 2-wire cooling valve and V2 a 2-wire heating valve.
3. Hidden-line wiring for Terminals V2 and 6 are applicable to dual-output models only.
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Inter-connecting wires: Cat 5e twisted 6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 9

10 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin
Wiring Diagram for Line-Voltage Fan and Single Line-Voltage 3-Wire Floating Valve Output
Piping Notes:
1. V must be a line-voltage 3-wire floating valve.
2. In cooling mode, V1 output opens valve on temperature rise and V2 output closes
valve on temperature drop. The action in heating mode is reversed.
Inter-connecting wires: Cat 5e twisted 6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable

Wiring Diagram for Line-Voltage Fan and Single 24 VAC 3-Wire Floating Valve Output
Piping Notes:
1. V must be a 24 VAC 3-wire floating valve.
2. In cooling mode, V1 output opens valve on temperature rise and V2 output closes valve
on temperature drop. The action in heating mode is reversed.
Inter-connecting wires: Cat 5e twisted 6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 11

Wiring Diagram for Line-Voltage Fan and Dual Line-Voltage 3-Wire Floating Valve Outputs
Piping Notes:
1. V1 must be a 3-wire floating cooling valve.
2. V2 must be a 3-wire floating heating valve.
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Inter-connecting wires: Cat 5e twisted 6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
12 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin

Wiring Diagram for Line-Voltage Fan and Dual 24 VAC 3-Wire Floating Valve Outputs
Piping Notes:
1. V1 must be a 3-wire floating cooling valve.
2. V2 must be a 3-wire floating heating valve.
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Inter-connecting wires: Cat 5e twisted
6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 13

Wiring Diagram for Line-Voltage Fan and 0-10 VDC Valve Outputs
Piping Notes:
1. On a single-output unit, V1 can be a cooling or heating valve.
2. On a dual-output unit, V1 must be a cooling valve and V2 a heating valve.
3. Hidden-line wiring for Terminals V2 and 6 are applicable to dual-output models only.
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
14 NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin
Inter-connecting wires: Cat 5e twisted
6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable

Wiring Diagram for Line-Voltage Fan and 0-10 VDC Cooling Valve and Line-Voltage 2-Wire On-Off
Heating Device Outputs
Piping Notes:
1. V1 must be a 0-10 VDC cooling valve.
2. H must be a line-voltage on-off heating device.
WARNING
Incorrect wiring connection may
cause permanent equipment dam-
ages to the thermostat.
Inter-connecting wires: Cat 5e twisted
6-conductor cable (shielded or unshielded)
Power wires: wire size
1 mm2 or 18 AWG solid
copper recommended
RS485 communications wires:
22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
Sensor wires: 22 AWG twisted shielded pair
double-insulated cable
NT10, 18-03(Mega) NT10 Series RS-485 Modbus RTU Networking Room Thermostats Product Bulletin 15
Mega Controls Limited
Room 1521A, Star House
3 Salisbury Road, Tsimshatsui, Kowloon, Hong Kong
WhatsApp Text & Call: [phone] E-mail: [e-mail] Website: www.megacontrols.com