AERCO BMK 1500-2000 - Manual (Page 123)

Benchmark 1500 - 2000 Boilers
CHAPTER 10. BOILER SEQUENCING TECHNOLOGY
OMM-0097_0D AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 123 of 188
GF-142
Ph.: 800-526-0288
10.3.4 Option 4 - Outdoor Reset with MODBUS Header Sensor AND MODBUS
Outdoor Sensor
NOTE: Both Header Sensor AND Outdoor Sensor must be wired. See the C-More Controller User
Manual, OMM-0032, GF-112 and ProtoNode User Manual, OMM-0080, GF-129 for more information.
Step 1 - Modbus Header Sensor Wiring
1. Using Shielded pair 18 - 22 AWG cable, connect the Temperature Transmitter (AERCO P/N 65169)
terminal Pin B to the RS485+ terminal on the I/O Box of any of the Boiler units, and Pin A of the
Temperature Transmitter to the RS485- terminal on the I/O Box of any of the Boiler units.
2. Using Shielded pair 18 - 22 AWG cable, connect the Modbus Header Temperature Sensor (AERCO
PN 24410) to pins 2 and 3 of the Temperature Transmitter.
3. Install a jumper wire between pins 1 and 2 of the Temperature Transmitter.
NOTES:
• Polarity must be observed for the RS485 connections. The ground for the shield is at the “SHLD”
terminal in the I/O the Box.
• The header sensor must be installed between 2 and 10 feet downstream of the LAST boiler in the
plant’s supply water header.
• There is no polarity to be observed. The ground for the shield is at the power supply ground. The
sensor end of the shield must be left free and ungrounded.
Step 2 - Modbus Outdoor Sensor Wiring
1. If you have not already done so when installing the Modbus Header Sensor, use Shielded pair 18 - 22
AWG cable to connect the Temperature Transmitter terminal Pin B to the RS485+ terminal on the I/O
Box of any of the Boiler units, and Pin A of the Temperature Transmitter to the RS485- terminal on the
I/O Box of any of the Boiler units.
2. Using Shielded pair 18 - 22 AWG cable, connect the Modbus Header Temperature Sensor (AERCO
PN 24410) to pins 2 and 3 of the Temperature Transmitter.
3. Install a jumper wire between pins 1 and 2 of the Temperature Transmitter.
NOTES:
• Polarity must be observed for the RS485 connections. The ground for the shield is at the “SHLD”
terminal in the I/O the Box.
• When mounting the Outdoor sensor, it must be located on the North side of the building where an
average outside air temperature is expected. The sensor must be shielded from direct sunlight as
well as impingement by the elements. The outdoor sensor may be wired up to 200 feet from the
boiler.
Temp Sensor PN 24410 Modbus Transmitter I/O Box