Outdoor Air & Air Sensor Common - Watts AERCO Benchmark BMK750 Installation And Start-Up Manual

Benchmark 750-6000 with Edge [i]: Install-Startup Manual
SECTION 2 – INSTALLATION
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.
2.11.1 Outdoor Air & Air Sensor Common
An outdoor temperature sensor (P/N 61047) is required for the Outdoor Air Reset operating
mode. 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 OFF. To enable the sensor, see the Outdoor Air
Temp Sens parameter in the
Configuration menu.
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.
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.
OMM-144_B • GF-217 •
5/25/2020
DIP 1 Modbus Term
DIP 2 RS232 Enable
Figure 2-11: I/O Box Terminal Strips
Main Menu → Advanced Setup → BST Cascade → Cascade
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
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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