Outdoor Air & Air Sensor Common - Watts Aerco Benchmark OMM-0116 Installation And Start-Up Manual

Benchmark 750-3000 Installation & Startup Manual
SECTION 2 – INSTALLATION
Outdoor Air
Air Sensor Common
Air Temp Sensor
O2 Sensor –
Not Used
Spark Signal +
Spark Signal –
O2 Sensor +
Not Used
+12 V Out
Analog In +
Analog In –
Valve Feedback +
Valve Feedback –
Shield
Shield
Analog Out +
Analog Out –
RS-485 +
RS-485 Ground
RS-485 -
RS-232 - TxD
RS-232 - RxD
VFD/Blower +
VFD/Blower –
NOTE:
Refer to this image for connections rather than the silkscreen labels shown on the board.
WARNING!
DO NOT make any connections to the I/O Box terminals labeled "NOT USED". Attempting to
do so may cause equipment damage.
2.11.1 Outdoor Air & Air Sensor Common
An outdoor temperature sensor (P/N 61047) is required 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, which 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 Section 2.6: CONFIGURATION Menu, item 7, in the
Benchmark 750 – 3000 Operation and Maintenance Guide, OMM-0116 (GF-201).
The outdoor sensor may be wired up to 200 feet (61m) from the boiler. It is connected to the
OUTDOOR AIR and AIR SENSOR COMMON terminals of the I/O board (Figure 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 PCB. The sensor end of the shield must be left free and ungrounded.
• •
OMM-115_D GF-200 5/9/2019
DIP 1 Modbus Term
DIP 2 RS232 Enable
Figure 2-11: I/O Box Terminal Strips
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
126
Remote Intl'k OUT
Remote Intl'k IN
NOT USED
Delayed Intl'k OUT
Delayed Intl'k IN
Not Used
Fault Relay N.C.
Fault Relay COMM
Fault Relay N.O.
Aux Relay N.C.
Aux Relay COMM
Aux Relay N.O.
Not Used
Relay Contacts:
120 VAC, 30 VDC
5 Amps, Resistive
DANGER!
120 VAC USED
IN THIS BOX
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