Benchmark 2500 - 3000 Boilers
CHAPTER 9. BOILER SEQUENCING TECHNOLOGY
OMM-0094_0F
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
125
of
207
GF-137
Ph.: 800-526-0288
09/30/2015
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