AERCO BMK 6000 Dual Fuel - Manual (Page 77)

Benchmark 6000 DF Installation, Operation & Maintenance Manual
CHAPTER 5 – MODE OF OPERATION
OMM-0096_0B AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 77 of 219
GF-141
Ph.: 800-526-0288
03/21/2014
If the Network setting is selected for RS-485 Modbus operation, a valid Comm Address must be
entered in the Setup Menu. Refer to Modbus Communication Manual GF-114 for additional
information.
5.5.1 Direct Drive Field Wiring
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.
5.5.2 Direct Drive Startup
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 AERCO CONTROL SYSTEM (ACS)
NOTE
ACS utilizes RS-485 signaling to the boiler.
The ACS mode of operation is used in conjunction with an AERCO Control System. The ACS
mode is used when it is desired to operate multiple units in the most efficient manner possible.
For this mode of operation, an ACS Header Sensor must be installed between 2 and 10 feet
downstream of the LAST boiler in the boiler plant's supply water header. The ACS can control up
to 40 boilers; 8 via pulse width modulation (PWM) and up to 32 via Modbus (RS-485) network
communication. The ACS can control up to 32 boilers via RS-485 network communication. For
programming, operation, and Header Sensor installation details, see GF-131 (ACS) Operations
Guide. For operation via an RS-485 Modbus network, refer to Modbus Communication Manual
GF-114.
To enable the ACS Mode, the following menu settings must be made in the Configuration Menu:
Menu Option Setting
Boiler Mode Direct Drive
Remote Signal Network (RS-485)
Refer to section 3.3 for instructions on changing menu options.