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Benchmark 750-3000 Boiler Installation & Startup Manual
SECTION 6 – BOILER SEQUENCING TECHNOLOGY
OPTION 4 - Outdoor Reset With Modbus Header Sensor And Modbus
Outdoor Sensor Instructions
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 (61m) from the boiler.
•
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.
TEMP SENSOR P/N 61043
Step 3 - Configure ALL C-More Units
On ALL Boilers:
1. Go to the Configuration menu and set the BST Menu item to Enabled.
2. Go to the Boiler Sequencing Menu and set the BST Mode item to BST Client (for now).
On MANAGER only:
3. Go to the BST Setpoint item and enter the Failsafe Setpoint.
4. Go to the BST Setup Menu item and set to Enabled.
5. Go to the BST Setpoint Mode item and select Outdoor Reset.
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).
9. Go to the BST Outdoor Sens item and select Enabled.
10. Go to the Outdoor Temp Source item and select Network.
11. Go to the Outdoor Temp Addr item and enter the Modbus Address (240).
12. Go to the Outdoor Temp Point item and enter the Modbus Point (15).
When ALL C-More units have been configured:
13. Go to the Boiler Sequencing Menu of the Manager unit and set the BST Mode item to BST
MANAGER.
OMM-0121_D • GF-205 • 5/9/2019
MODBUS TRANSMITTER
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
I/O BOX
Page 106 of 122
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