Direct Drive Field Wiring; Direct Drive Startup - Aerco Benchmark BMK 750 User Manual

Benchmark 750-3000 Boiler Operation, Service, Maintenance Guide - KOREA
SECTION 3 – MODES OF OPERATION
NOTE:
If a voltage, rather than current signal is used to control the remote setpoint, a DIP switch
adjustment must be made on the CPU Board located in the C-More Controller. Contact your
local AERCO representative for details.
To enable the DIRECT DRIVE mode, you must set menu items Boiler Mode and Remote
Signal in the Configuration menu as follows:
TABLE 3-3: 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 2.3: C-More Controller Menus 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.

3.5.1 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.

3.5.2 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.
OMM-0128_0C
GF-206-K
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
Page 33 of 146
11/29/2017