AERCO BMK 1.5 LN July 2011 - Manual (Page 22)

CHAPTER 2: INSTALLATION
Page 22 of 152 PR2: 05/09/12
Benchmark 1.5LN Low NOx Boiler
Operation and Maintenance Manual
OMM-0041_0D
GF-120
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
Boiler Management System Mode 2.9.3
NOTE
BMS Model 168 can utilize either pulse width modulation (PWM)
or RS485 Modbus signaling to the Boiler. BMS II Model 5R5-384
can utilize only RS485 signaling to the Boiler.
When using an AERCO Boiler Management System (BMS), the field wiring is connected
between the BMS Panel and each Boiler’s I/O Box terminal strip (Figure 2-10). Twisted shielded
pair wire from 18 to 22 AWG must be utilized for the connections. The BMS Mode can utilize
either pulse width modulation (PWM) signaling, or RS485 Modbus signaling. For PWM
signaling, connections are made from the AERCO Boiler Management System to the B.M.S.
(PWM) IN terminals on the I/O Box terminal strip. For RS485 Modus signaling, connections are
made from the BMS to the RS485 COMM terminals on the I/O Box terminal strip. Polarity must
be maintained and the shield must be connected only at the AERCO BMS. The boiler end of the
shield must be left floating. For additional instructions, refer to Chapter 5, paragraph 5.6 in this
manual. Also, refer to GF-108M, BMS -Operations Guide.
Remote Setpoint and Direct Drive Modes 2.9.4
The Benchmark 1.5 Boiler can accept several types of signal formats from an Energy
Management System (EMS), Building Automation System (BAS) or other source, to control
either the setpoint (Remote Setpoint Mode) or air/fuel valve position (Direct Drive Mode) of the
Boiler. These formats are:
• 4 to 20 mA/1 to 5 VDC
• 0 to 20 mA/0 to 5 VDC
• PWM – (Pulse Width Modulated signal. See para. 2.10.4)
• Network (RS485 Modbus. See para. 2.10.7)
While it is possible to control a boiler or boilers using one of the previously described modes of
operation, it may not be the method best suited for the application. Prior to selecting one of
these modes of operation, it is recommended that you consult with your local AERCO
representative or the factory for the mode of operation that will work best with your application.
For more information on wiring the 4 to 20 mA / 1to 5VDC or the 0 to 20 mA / 0 to 5 VDC, see
paragraph 2.9.3.
Combination Mode 2.9.5
NOTE
Only BMS Model 168 can be utilized for the Combination Mode,
not the BMS II (Model 5R5-384).
With a Combination Mode unit, field wiring is between the unit’s I/O Box wiring terminals, the
CCP (Combination Control Panel), and the BMS (Boiler Management System). The wiring must
be accomplished using twisted-shielded pair wire from 18 to 22 AWG. Polarity must be
maintained. For further instructions and wiring diagrams, refer to the GF-108 Boiler
Management System Operations Guide and the CCP-1 data sheet.