Benchmark 1500 - 2000 Boilers
CHAPTER 9. BOILER SEQUENCING TECHNOLOGY
OMM-0097_0E AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 119 of 182
GF-142 Ph.: 800-526-0288 10/01/2015
9.3.2 Option 2 - Constant Setpoint with MODBUS Wired Header Sensor
Step 1: MODbus Header Sensor Wiring
1. Using Shielded pair 18 - 22 AWG cable, connect the Temperature Transmitter (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 (P/N
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 (0.61 and 3.1m) 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: Configure ALL C-More Units
On ALL Boilers:
1. Go to the Configuration menu item and set the BST Menu item to Enabled.
2. Go to the Boiler Sequencing Menu item and set the BST Mode item to BST Slave (for now).
On MASTER only:
3. Go to the BST Setpoint item and enter the desired Setpoint.
4. Go to the BST Setup Menu item and set to Enabled.
5. Go to the BST Setpoint Mode item and select Constant Setpoint.
6. Go to the Head Temp Source item and select Network.
7. Go to the Header Temp Addr item and enter the Modbus Address (240).
8. Go to the Header Temp Point item and enter the Modbus Point (14).
When ALL C-More units have been configured:
9. Go to the Boiler Sequencing Menu item of the desired Master unit and set the BST Mode item to
BST MASTER.
Temp Sensor PN 24410 Modbus Transmitter I/O Box
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