Watts Benchmark Aerco OMM-0122, Installation And Start-Up Manual

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Benchmark 750-3000 Boiler Installation & Startup Manual
SECTION 6 – BOILER SEQUENCING TECHNOLOGY
OMM-0121_D
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GF-205
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5/9/2019
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SECTION 6: BOILER SEQUENCING TECHNOLOGY
6.1 INTRODUCTION
The Boiler Sequencing Technology system (BST) is built into the C-More Controller. BST is an
integrated 8 boiler control system. It has its own sophisticated PID control system designed to
simultaneously control the light off and modulation of up to 8 boilers while achieving maximum
operational efficiency.
BST is designed to ensure that all Boilers in the system operate at maximum efficiency. This is
accomplished by lighting off boilers only when all ignited boilers reach or exceed a defined
Valve Position (Fire Rate). Operating all boilers below the defined Fire Rate “Next on VP” (for
Next Turn on Valve Position) insures that they are firing at their most efficient Fire Rate. One
unit the BST network is defined as the “Manager” unit and all other units on the network are
defined as “Client” units. The Manager monitors the system Header Temperature, and also
monitors all Client unit’s status information, efficiently controlling all units in order to achieve and
maintain the required BST Setpoint Temperature.
When there is a demand, the Manager will light off one of the boilers based on the BST
Sequencing selection in the BST menu. As system load increases and the valve position of the
ignited unit(s) reach the Next On VP (% valve position), the Manager will light off the next
available unit. A simplified block diagram of multiple Boilers connected to a BST is shown in
Figure 6-1 below.
Figure 6-1: Simplified BST Block Diagram
NOTE:
After the boiler load is satisfied, the isolation valve remains open for a programmed interval
(default = 2 minutes) before closing. When the
system load is satisfied, the C-More Controller
will open the
isolation valves for all of the boilers. The BST controls the valves via a 0-20 mA
signal (see section 2.11.8)
NOTE : Use either FFWD Header
Sensor or Modbus Header Sensor