Direct Drive Field Wiring; Direct Drive Startup - Watts Aerco BENCHMARK 750 User Manual

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
CPU Board located in the Control Box Assembly. Contact your
local AERCO representative for details.
To enable the DIRECT DRIVE mode, the following menu setting must be made in the
Configuration menu:
Menu Option
Boiler Mode
Remote Signal
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.

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.
OMM-0119_0A
GF-130-I
CHAPTER 5 – MODE OF OPERATION
Table 5-3: Direct Drive Mode Settings
Setting
Direct Drive
4-20mA/1-5V, 0-20mA/0-5V, or Network
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
Page 69 of 170
11/03/2016