AERCO BMK 1000 - Manual (Page 73)

Benchmark 750/1000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 5 – MODE OF OPERATION
OMM-0082_0J AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 73 of 192
GF-130
Ph.: 800-526-0288 05/21/2014
To enable the Direct Drive Mode, the following menu setting must be made in the Configuration
Menu:
Table 5-3: Direct Drive Mode Settings
Menu Option Setting
Boiler Mode Direct Drive
Remote Signal
4-20mA/1-5V,
0-20mA/0-5V, or Network
Refer to section 3.3 for instructions on changing menu options.
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 is for installations with 9 or more boilers. It utilizes only RS-485
signaling to the boiler. Installations with 1 to 8 boilers can use BST (see
Chapter 10).
The ACS mode of operation is used in conjunction with the 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; up to 32 via Modbus (RS-485) network communication. For ACS programming,