Benchmark 2.0 LN Installation, Operation & Maintenance Manual
CHAPTER 2 – INSTALLATION
OMM-0046_0J
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
25
of
168
GF-123
Ph.: 800-526-0288
06/18/2015
2.9.1 Constant Setpoint Mode
The Constant Setpoint Mode is used when it is desired to have a fixed setpoint that does not
deviate. No wiring connections, other than AC electrical power connections, are required for this
mode. However, if desired, fault monitoring (see paragraph 2.10.12) or enable/disable interlock
wiring can be utilized (see paragraph 2.10.11).
2.9.2 Indoor/Outdoor Reset Mode
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.
2.9.3 Boiler Management System Mode
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.
2.9.4 Remote Setpoint and Direct Drive Modes
The Benchmark 2.0LN 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 paragraph 2.10.4)
•
Network (RS-485 Modbus. See paragraph 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.
