AERCO BMK 3.0 LN Dual-Fuel Series Gas Fired Low NOx Boiler System - Manual (Page 19)

INSTALLATION
2-9
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.
2.9.5 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
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 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.
2.10 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 2-11 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.
2.10.1 OUTDOOR SENSOR IN
An outdoor air temperature sensor (AERCO Part
No. 122790) will be required primarily 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 select
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. It is connected to the
OUTDOOR SENSOR IN and SENSOR
COMMON terminals in the I/O Box (see Figures
2-10 and 2-11). Wire the sensor using a twisted
shielded pair wire from 18 to 22 AWG. There is
no polarity to observe when terminating these
wires. The shield is to be connected only to the
terminals labeled SHIELD in the I/O Box. The
sensor end of the shield must be left free and
ungrounded.
When mounting the sensor, it must be located
on the North side of the building where an
average outside air temperature is expected.
The sensor must be shielded from direct sunlight
as well as impingement by the elements. If a
shield is used, it must allow for free air
circulation.
2.10.2 AIR SENSOR IN
The AIR SENSOR IN is connected to the AUX
SENSOR IN and SENSOR COMMON terminals
on the I/O board. The AIR SENSOR measures
the temperature of the air input to the Air/Fuel
Valve. This temperature reading is one of the
components used to calculate the rotational
speed of the blower used in the combustion
Calibration process (Chapter 4).
The AUX SENSOR IN terminals can be used to
add an additional temperature sensor for
monitoring purposes. This input is always
enabled and is a view-only input that can be
seen in the Operating Menu. The sensor must
be wired to the AUX SENSOR IN and SENSOR
COMMON terminals and must be similar to
AERCO BALCO wire sensor Part No. 12449. A
resistance chart for this sensor is provided in
Appendix C.
2.10.3 ANALOG IN
The ANALOG IN + and – terminals are used
when an external signal is used to drive the
Air/Fuel Valve % open position (Direct Drive
Mode) or change the setpoint (Remote Setpoint
Mode) of the Boiler.
Either a 4 to 20 mA /1 to 5 VDC or a 0 to 20 mA
/ 0 to 5 VDC signal may be used to vary the
setpoint or Ar/Fuel Valve position. The factory
default setting is for 4 to 20 mA / 1 to 5 VDC,
however this may be changed to 0 to 20 mA / 0
to 5 VDC using the Configuration Menu
described in Chapter 3. If voltage rather than
current is selected as the drive signal, a DIP
switch must be set on the PMC Board located
inside the Control Box. Refer to C-More Control
Panel Operation Manual GF-112 for information
on setting DIP switches.
All of the supplied signals must be floating
(ungrounded) signals. Connections between the
signal source and the Boiler’s I/O Box must be
made using twisted shielded pair wire from 18 to
22 AWG, such as Belden 9841 (see Figure
2-11). Polarity must be maintained. The shield
must be connected only at the source end and
must be left floating (not connected) at the
Boiler’s I/O Box.
Regardless of whether voltage or current is used
for the drive signal, they are linearly mapped to
a 40°F to 240°F setpoint or a 0% to 100% valve