AERCO BMK 2.0 LN for Mass. only - Manual (Page 19)

INSTALLATION
2-7
2.6.3 BOILER MANAGEMENT SYSTEM
(BMS) MODE
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 2-9). 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 Modbus 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
Model 168) and GF-124 (BMS II Model 5R5-
384), BMS -Operations Guides.
2.6.4 REMOTE SETPOINT and DIRECT
DRIVE MODES
The Benchmark Boiler can accept several types
of signal formats from an Energy Management
System or other source to control either the
setpoint (Remote Setpoint Mode) or firing rate
(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 2.7.4)
Network – (RS485 Modbus. See para. 2.7.7)
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 2.7.3.
2.6.5 COMBINATION MODE
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
connected between the unit’s I/O Box wiring
terminals, the CCP (Combination Control Panel),
and the BMS Model 168 (Boiler Management
System). The wiring must be done using a
shielded twisted pair of 18- 22 AWG wire and
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.
2.7 I/O BOX CONNECTIONS
The types of input and output signals and
devices to be connected to the I/O Box terminals
shown in Figure 2.9 are described in the
following paragraphs.
CAUTION!
DO NOT make any connections to the I/O Box
terminals labeled “NOT USED”. Attempting to
do so may cause equipment damage.
2.7.1 OUTDOOR SENSOR IN
An outdoor air temperature sensor (AERCO Part
No. 122790) will be required mainly for the
Indoor/Outdoor reset mode of operation. It can
also be used with another mode if it is desired to
use the outdoor sensor enable/disable feature.
This feature allows the boiler to be enabled or
disabled based on the outdoor air temperature.
The factory default for the outdoor sensor is
DISABLED. To enable the sensor and/or choose
an enable/disable outdoor temperature, see the
Configuration menu in Chapter 3.
The outdoor sensor may be wired up to 200 feet
from the boiler and is connected to the
OUTDOOR SENSOR IN and SENSOR
COMMON terminals in the I/O box (see Figs. 2.8
and 2.9). Wire the sensor using a twisted
shielded pair cable of 18-22 AWG wire. There is
no polarity when terminating the wires. The