AERCO BMK 2.0 LN Natural Gas (SN G-11-1861 and above) - Manual (Page 28)

Chapter 2
Benchmark 2.0LN Low NOx Boiler
GF-123
Installation Installation, Operation and Maintenance Manual OMM-0046_0E
Page 28 of 170 AERCO International Inc.● 100 Oritani Dr. ● Blauvelt, NY 10913. ● Ph: 800-526-0288 PR1 08/20/12
2.10.5 SHIELD
(5)
The SHIELD terminals are used to terminate any shields used on sensor wires connected to the
unit. Only shields must be connected to these terminals.
IMPORTANT
DO NOT USE the mA OUT output to remotely monitor Setpoint, Outlet
Temp or Fire Rate Out.
2.10.6 mA OUT
(6)
These terminals provide a 4 to 20 mA output to the VFD (if so equipped) to control the rotational
speed of the blower. This function is enabled in the Configuration Menu (Chapter 3, Table 3-4).
2.10.7 RS-485 COMM
(7)
These terminals are used for RS-485 MODBUS serial communication between the unit and an
external “Master” such as a Boiler Management System (BMS), AERCO Control System (ACS),
Energy Management System (EMS), Building Automation System (BAS) or other suitable
device.
2.10.8 TxD, RxD
(8)
These terminals provide a parallel connection to the connector on the C-More Controller front
panel, for connecting a computer or laptop.
2.10.9 VFD/BLOWER
(9)
These terminals provide a 0 to 10 volt output to control the rotational speed of the blower. This
function is enabled in the Configuration Menu (Chapter 3, Table 3-4).
2.10.10 EXHAUST SWITCH IN
(11)
These terminals permit an external exhaust switch to be connected to the exhaust manifold of
the boiler. The exhaust switch should be a normally open type switch (such as AERCO Part No.
123463) that closes (trips) at 500°F.
2.10.11 INTERLOCKS
(10, 12)
The unit offers two interlock circuits for interfacing with Energy Management Systems and
auxiliary equipment such as pumps or louvers. These interlocks are called the Remote Interlock
and Delayed Interlock (Figure 2-10). The wiring terminals for these interlocks are located inside
the I/O Box on the unit front panel. The I/O Box cover contains a wiring diagram which shows
the terminal strip locations for these interlocks (REMOTE INTL’K IN and DELAYED INTL’K IN).
Both interlocks, described below, are factory wired in the closed position.
NOTE
Both the Delayed Interlock and Remote Interlock MUST be in the closed position to allow the
unit to fire.