NTI INSTALLATION MANUALS

Part 7 - Connecting Electrical Service

4. Room Thermostat Wiring Connections

To connect a room thermostat: 1. Access the low voltage wiring connections by following the directions in Item 3, Low Voltage Wiring Connections. 2. Loosen the cable clamp using a screwdriver and insert the wires leading from the room thermostat. 3. Connect the room thermostat wires to the terminals indicated in Table 19 and Figure 68. 4. Ensure that the wires are well connected and not subject to stress when the control panel or cabinet cover are closed. CAUTION NOTE: Some newer thermostat models may draw too much power from the boiler and will require an additional power supply to operate properly. Review the instructions provided with the thermostat to determine if an additional power supply is needed. Failure to do so could result in improper boiler and/or thermostat operation.

Figure 68 - 120V Connections for DHW and CH Circulators

Low Voltage Wiring Connections

BUS

Remote Control Connection

TT2

Room Thermostat 2

OD

Outdoor Sensor

5. Outdoor Sensor Connections

TNK

Tank Temperature Sensor (Probe / Aquastat)

NOTE: WHEN CONNECTING THE BOILER TO EXTERNAL CONTROLS, DO NOT RUN 120V CABLES AND CABLES FOR CONTROL CIRCUITS (WHICH ARE LOW VOLTAGE) TOGETHER. USE SEPARATE CABLES TO PREVENT INDUCED VOLTAGE ON THE LOW VOLTAGE CIRCUITS.

SYS

System Sensor (Cascade Manager)

TT1

Room Thermostat 1

Table 19 - Low Voltage Wiring Connections

Outdoor Sensor

Remote Control (optional)

Outdoor Sensor

Tank temp. probe

System Sensor

OK

Room Thermostat

1

2

3

4

5

6

7

BUS T B 120V

5V IN TT2 OD TNK SYS TT1 120V 120V 120V 120V 120V

CN1

Connector OD on PCB

Figure 67 - Outdoor Sensor Connection

6. Aquastat (Default) and Tank Sensor (Optional) Connections (non-Combi Models) The boiler is designed for managing the production of domestic hot water via an indirect water heater (IWH) in one of two ways: i. AQUASTAT (default) - with parameter 228 = 2, the tank temperature is managed through an ON/OFF aquastat installed in the tank. ii. TANK SENSOR (optional) - with parameter 228 = 1, the boiler manages the IWH temperature directly via an NTC sensor installed in the tank and connected to the boiler (see electrical diagram). The setting of the tank temperature is done through the “+” and “-” buttons on the left side of the display.

Figure 69 - Low Voltage Wiring Connections

CAUTION DO NOT CONNECT 120V TO ANY CONTROL WIRING CONNECTION! DOING SO WILL RESULT IN IMPROPER OPERATION AND POSSIBLE DAMAGE TO THE BOILER. SUCH DAMAGES ARE NOT COVERED BY PRODUCT WARRANTY!

NOTICE REMOVE THE JUMPER FROM TT1.

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