CHAPTER 2: INSTALLATION
Page
20
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158
PR2: 04/22/13
Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc.
•
100 Oritani Dr.
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Blauvelt, NY 10913
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Ph: 800-526-0288
utilized (see paragraphs 2.10.11.1 and 2.10.11.2).
Indoor/Outdoor Reset Mode
2.9.2
This mode of operation increases supply water temperature as outdoor temperatures decrease.
An outside air temperature sensor (AERCO Part No. 122790) is required. The sensor MUST
BE wired to the I/O Box wiring terminals (see Figure 2-10). Refer to paragraph 2.10.1 for
additional information on outside air temperature sensor installation.
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
and the AERCO Control System (ACS) can utilize only RS485
signaling to the Boiler.
When using an AERCO BMS, BMS II, or ACS (AERCO Control System), the field wiring is
connected between the BMS/BMS II/ACS 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/BMS II/ACS 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/BMS II/ACS. 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), GF-124 (BMS II Model 5R5-384), and GF-131 (ACS) operation manuals.
Remote Setpoint and Direct Drive Modes
2.9.4
The 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:
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4 to 20 mA/1 to 5 VDC
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0 to 20 mA/0 to 5 VDC
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PWM – (Pulse Width Modulated signal. See para. 2.10.4)
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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 2.10.3.
Combination Mode
2.9.5
NOTE
Only BMS Model 168 and ACS 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
