Troubleshooting guide

INSTALLATION
2-7
2.9 MODES OF OPERATION AND FIELD
CONTROL WIRING
The Benchmark 3.0 Dual-Fuel Boiler is available
in several different modes of operation. While
each unit is factory configured and wired for its
intended mode, some additional field wiring may
be required to complete the installation. This
wiring is typically connected to the Input/Output
(I/O) Box located on the lower portion of the unit
front panel (Figure 2-10) behind the removable
front door.
To access the I/O Box terminal strips shown in
Figure 2-10, loosen the four cover screws and
remove the cover. All field wiring is installed
from the rear of the panel by routing the wires
through one of the four bushings provided.
Refer to the wiring diagram provided on the
cover of the I/O Box (Figure 2-11) when making
all wiring connections.
In addition to the terminal strips shown in Figure
2-10, the I/O Box also contains a pre-wired
temperature transmitter which receives inlet air
temperature sensor readings and transmits this
signal to the variable frequency drive (VFD)
contained in the Benchmark 3.0 Dual-Fuel
Boiler. The VFD utilizes this input signal to
adjust the rotation speed of the blower.
Figure 2-10.
Input/Output (I/O) Box Location
Brief descriptions of each mode of operation,
and their wiring requirements, are provided in
the following paragraphs. Additional information
concerning field wiring is provided in paragraphs
2.9.1 through 2.9.9. Refer to Chapter 5 for
detailed information on the available modes of
operation.
mA OUT
RS-485
COMM.
+
-
+
-
ANALOG IN
SENSOR COMMON
OUTDOOR SENSOR IN
REMOTE INTL'K IN
B.M.S. (PWM) IN
SHIELD
+
-
+
-
AUX SENSOR IN
NOT USED
EXHAUST SWITCH IN
DELAYED INTL'K IN
FAULT RELAY
120 VAC, 5A, RES
AUX RELAY
120 VAC, 5A, RES
G
RELAY CONTACTS:
120 VAC, 30 VDC
5 AMPS RESISTIVE
DANGER
120 VAC USED
IN THIS BOX
NOT USED
NOT USED
NC
COM
NO
NC
COM
NO
NOT USED
Figure 2-11. I/O Box Terminal Strip