LAARS NeoTherm NTH (Sizes 285–850 MBTU/h) - Installation Manual - Manual (Page 3)

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H2368400
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FIELD CONNECTIONS: (continued)
• Using the two (2) supplied thermistor cables, connect one Shielded
cable to the 1 and 2 landing points on terminal block (TB2) of the
VARI-PRIME board.
Important: This wire will be run to the OUTLET sensor.
• Connect one end of the VFD signal wire to the
VFD on the chosen pump as instructed in pump
manual. Connect the other end to the 3 and 4
landing points on terminal block (TB3).
Important: #3 landing point is for
0-10 VDC (+) and #4 is for 0-10 VDC(-).
• Connect the other Shielded cable to the 3 and 4 landing points on
terminal block (TB2) of the VARI-PRIME board.
Important: This wire will be run to the INLET sensor.
• Tap two ¼” NPT threaded holes into water pipes for the sensors. One in the supply pipe and the other in the return. Both
sensors need to be inserted into the pipe no more than 12” away from the outside of the boiler jacket. These two sensors will
be the Delta T. (Note: Delta T is the difference between supply and return water temperatures) The amount of Delta T is
chosen on Vari-Prime terminal block (JP2). Install the Sensors.