Benchmark 2500 - 3000 Boilers
CHAPTER 2 – INSTALLATION
OMM-0094_0F
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
27
of
207
GF-137
Ph.: 800-526-0288
09/30/2015
Figure 2-12: I/O Box Terminal Strips
2.10.1 OUTDOOR AIR IN Terminal
The OUTDOOR AIR IN terminal is used for connecting an outdoor temperature sensor (P/N
GM-123525
) as 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 (61 m)
from the boiler. It is connected to the
OUTDOOR AIR IN and AIR SENSOR COMMON terminals of the I/O PCB (Figure 2-12). 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 PCB. 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 TEMP SENSOR Terminals
The AIR TEMP SENSOR terminals are used to monitor the air inlet temperature sensor (P/N
61024
). This input is always enabled and is a “to view only” input that can be seen in the
Operating
menu. A resistance chart for this sensor is provided in APPENDIX C. This sensor is
