AERCO BMK 1.5 LN July 2011 - Manual (Page 23)

CHAPTER 2: INSTALLATION
PR2: 05/09/12 Page 23 of 152
Benchmark 1.5LN Low NOx Boiler
Operation and Maintenance Manual
OMM-0041_0D
GF-120
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
Figure 2-10. I/O Box Terminal Locations and Functions
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 2-10 are described in the following paragraphs.
NOTE
Older I/O PCBs are wired the same as new ones, even if silk-
screen designations may slightly differ.
DO NOT make any connections to the I/O Box terminals labeled
“NOT USED”. Attempting to do so may cause equipment
damage.
OUTDOOR SENSOR IN (1) 2.10.1
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 2-9 and
2-10). 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