AERCO BMK 1.5 LN Dual Fuel Feb 2013 - Manual (Page 63)

CHAPTER 5: MODE OF OPERATION
PR2: 05/09/12 Page 63 of 162
Benchmark 1.5LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0041_0C
GF-121
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
Menu. Refer to Modbus Communication Manual GF-114 for additional information.
Direct Drive Field Wiring 5.5.1
The only wiring connections necessary for Direct Drive mode are connection of the remote
signal leads from the source to the unit’s I/O Box. For either a 4-20mA/0-5V or a 0-20mA/0-
5V setting, the connections are made at the ANALOG IN terminals in the I/O Box. For a
Network setting, the connections are made at the RS-485 COMM terminals in the I/O Box.
The signal must be floating, (ungrounded) at the I/O Box and the wire used must be a two
wire shielded pair from 18 to 22 AWG. Polarity must be observed. The source end of the
shield must be connected at the source. When driving multiple units, each unit’s wiring must
conform to the above.
Direct Drive Startup 5.5.2
Since this mode of operation is factory preset and the valve position is being externally
controlled, no startup instructions are necessary. In this mode, the REMOTE LED will light
when the signal is present.
To operate the unit in manual mode, press the
AUTO/MAN switch. The REMOTE LED will
go off and the MANUAL LED will light.
To change back to the Direct Drive mode, simply press the AUTO/MAN switch. The
REMOTE LED will again light and the MANUAL LED will go off.
5.6 BOILER MANAGEMENT SYSTEM (BMS, BMS II, or ACS)
NOTE
BMS Model 168 can utilize either pulse width modulation
(PWM) or RS485 Modbus signaling to the Boiler. The BMS II
and the ACS (AERCO Control System) can utilize only RS485
signaling to the Boiler.
The BMS mode of operation is used in conjunction with an AERCO Boiler Management
System (BMS or BMS II) and the AERCO Control System (ACS). The BMS mode is used
when it is desired to operate multiple units in the most efficient manner possible. For this
mode of operation, a BMS Header Sensor must be installed between 2 and 10 feet
downstream of the LAST boiler in the boiler plant's supply water header. The BMS can
control up to 40 boilers; 8 via pulse width modulation (PWM) and up to 32 via Modbus
(RS485) network communication. For BMS/BMS II/ACS programming, operation, and
Header Sensor installation details, see GF-108M (BMS Model 168), GF-124 (BMS II Model
5R5-384), and GF-131 (ACS) Operations Manuals. For operation via an RS485 Modbus
network, refer to Modbus Communication Manual, GF-114.
To enable the BMS Mode, the following menu settings must be made in the Configuration
Menu:
MENU
OPTION
SETTING
Boiler Mode Direct Drive
Remote
Signal
BMS (PWM Input)
or Network (RS485)
Refer to paragraph 3.3 for instructions on changing menu options.