Aerco Benchmark G-00-711, User Manual

Page: 12 / 79

INSTALLATION
2-6
Figure 2.11
Control Wiring Terminal Strip
2.6.2 INDOOR/OUTDOOR RESET MODE
This mode of operation increases supply water
temperature as outdoor temperatures decrease.
An outside air temperature sensor (AERCO PN
122790) MUST BE wired to the control wiring
terminals using a twisted shielded pair of 18-22
AWG wire (see Fig. 2.11). The cable shield is
connected only at the terminals provided at the
control wiring terminal strip located at the bottom
left hand corner of the control panel. The sensor
end of the shield must be left free and
ungrounded. There is no polarity in terminating
the sensor wires. When mounting the sensor, it
must be mounted on the north side of the
building in an area where the average outside
air temperature is expected. The sensor must be
shielded from the sun's direct rays, as well as
direct impingement by the elements. If a cover
or shield is used, it must allow free air
circulation. The sensor may be mounted up to
two hundred feet from the unit.
2.6.3 BOILER MANAGEMENT SYSTEM
MODE
When using an AERCO Boiler Management
System Panel, Model 168, the field wiring is
between the BMS Panel and each unit’s control
wiring terminal (see Fig. 2.11). A twisted
shielded pair of 18 to 22 AWG wire must be
utilized for the connections. Connections are
made from the AERCO boiler management
system to terminals 2 and 3 of the boiler's
control terminal wiring strip. Polarity must be
maintained and the shield is to be connected
only at the AERCO boiler management system
and must be left floating at the boiler. For further
wiring instructions see the GF-108, BMS
Operations Guide.
2.6.4 4 to 20mA REMOTE SETPOINT and
DIRECT DRIVE MODES
The BENCHMARK boiler can be controlled with
a 4-20mA signal from an energy management
system or an external controller. The 4-20mA is
linearly mapped to a 40-220
o
F set point or to 0
to 100% input.
All supplied 4-20mA signals must be a floating
(ungrounded) signal. Connections between the
4-20mA source and the unit's control wiring
terminals must be made using a twisted shielded
pair of 18-22 AWG wire such as Belden 9841
(see Fig. 2.11). The shield is connected only at
the terminal provided on the control wiring
terminals. The shield must be left free and
ungrounded at the source end. Polarity must be
maintained when connecting the wires.
2.6.5 COMBINATION MODE
With a Combination Mode unit, field wiring is
between the unit’s control wiring terminals, the
CCP (Combination Control Panel), and the BMS
(Boiler Management System). The wiring must
be done using a shielded twisted pair of 18- 22
AWG wire and polarity must be maintained. For
further instructions and wiring diagrams, consult
the GF-108, Boiler Management System
Operations Guide and the CCP-1 data sheet.
2.7 AUXILLIARY CONTACTS
Each boiler is equipped with a SPDT relay that
is powered when there is a demand for heat.
The relay is provided for the control of auxiliary
equipment such as pumps and louvers. Its
contacts are rated for 120 VAC @ 5 amps (see
figure 2.11 terminals 5,6 and 7 for wiring
location).
2.8 INTERLOCKS
The Benchmark boiler offers two interlock
circuits for interfacing with energy management
systems and auxiliary equipment such as pumps
or louvers (see figure 2.12). These interlocks are
located on the inside of control panel door and
are labeled Enable/Disable and Delayed
Interlock
. Both interlocks, described below, are
factory wired closed and must be closed,
(jumped), to allow the unit to fire.
2.8.1 DELAYED INTERLOCKS
The delayed interlocks are typically used in
conjunction with the auxiliary relay described
above in section 2.7. This interlock circuit is
located in the purge control section of the start