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Benchmark 5000-6000 Boiler Installation & Startup Manual
SECTION 2: INSTALLATION
2.11.2 AIR TEMP SENSOR
The AIR TEMP SENSOR terminal is used to monitor the air inlet temperature sensor (P/N
123449). This input is always enabled and is a "view only" input in the AIR TEMP setting in the
Operating menu (see Section 2.4: OPERATING Menu, item 4, of the Benchmark 5000 – 6000
Operation and Maintenance Guide, OMM-0124 (GF-208). A resistance chart for this sensor is
provided in APPENDIX C of the same guide. This sensor is an active part of the combustion
control system and must be operational for accurate air/fuel mixing control.
2.11.3 O
SENSOR (+ & –)
2
SENSOR terminals (+ and –) are used to connect an integrated oxygen sensor to
The two O
2
the I/O board. The O
concentration is displayed in the Operating menu of the C-More Controller
2
after a 60 second warm-up period. See Section 2.4: OPERATING Menu, item 13, of the
Benchmark 5000 – 6000 Operation and Maintenance Guide, OMM-0124 (GF-208).
2.11.4 SPARK SIGNAL (+ & –)
Not in use on Benchmark 5000 and 6000.
2.11.5 ANALOG IN
The two ANALOG IN terminals (+ and –) are used when an external signal is used to change
the setpoint (REMOTE SETPOINT mode) of the boiler.
Either a 4 to 20 mA/1 – 5 VDC or a 0 to 20 mA/0 – 5 VDC signal may be used to vary the set-
point or air/fuel valve position. The factory default setting is 4 to 20 mA/1 to 5 VDC, however
this may be changed to 0 to 20 mA/0 – 5 VDC in the Configuration menu; see Section 2.6:
CONFIGURATION Menu, item 6, in the Benchmark 5000 – 6000 Operation and Maintenance
Guide, OMM-0124 (GF-208).
If voltage rather than current is selected as the drive signal, a DIP switch must be set on the
PMC Board located inside the C-More Controller. Contact the AERCO factory for information on
setting DIP switches.
All supplied signals must be floating (ungrounded) signals. Connections between the source
and the boiler's I/O board (Figure 2-14) must be made using twisted shielded pair of 18–22
AWG wire such as Belden 9841. Polarity must be maintained and the shield must be connected
only at the source end and must be left floating (not connected) at the Boiler's I/O board.
Whether using voltage or current for the drive signal, they are linearly mapped to a 40°F to
240°F (4.4°C to 116°C) setpoint or a 0% to 100% air/fuel valve position. No scaling for these
signals is provided
2.11.6 VALVE FEEDBACK
The two VALVE FEEDBACK terminals (+ and –) are used when the Sequencing Isolation Valve
Feedback option is selected. The Valve Feedback signal is connected to the "Valve Fdbk"
terminals and is used to confirm that the valve has properly opened or closed. If the Valve
Feedback signal does not match the Valve-Open or Valve-Close command for the time defined
in the "Valve Fdbk timer" entry, the C-More Controller will proceed as follows:
(a) If the valve fails with the Valve Stuck Open fault, the "Valve Stuck Open" message will
be displayed and the unit will remain active.
OMM-0123_E • GF-207 • 12/17/2019
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Page 28 of 95
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