AERCO KC Series Equipped with C-More version 3.04 - Manual (Page 17)

INSTALLATION
2-7
2.6.1 OUTDOOR AIR SENSOR IN
Not applicable to Water Heaters.
2.6.2 AUX SENSOR IN
The AUX SENSOR IN terminals can be used to
add an additional temperature sensor for
monitoring purposes. This input is always
enabled and is a view only input that can be
seen in the operating menu. The sensor must be
wired to the AUX SENSOR IN and SENSOR
COMMON and must be similar to AERCO
BALCO wire sensor P/N 12449. A resistance
chart for this sensor can be found in Appendix C.
2.6.3 ANALOG IN
The ANALOG IN + and – terminals are used
when an external signal is used to change the
setpoint of the water heater when operating in
the Remote Setpoint Mode.
Either a 4 to 20 mA / 1 to 5 VDC or a 0 to 20 mA/
0 to 5 VDC signal may be used to vary the
setpoint or air/fuel valve position. The factory
default setting is for 4 to 20 mA / 1 to 5 VDC,
however this may be changed to 0 to 20 mA / 0
to 5 VDC using the Configuration Menu
described in Section 3. If voltage rather than
current is selected as the drive signal, a DIP
switch must be set on the CPU Board located
inside the Control Box. Contact the AERCO
factory for information on setting DIP switches.
All supplied signals must be floating
(ungrounded) signals. Connections between the
source and the Heater’s I/O Box must be made
using twisted shielded pair wire of 18 –22
AWG,,such as Belden 9841(see Fig. 2.10).
Polarity must be maintained and the shield must
be connected only at the source end. It must be
left floating (not connected) at the Heater’s I/O
Box.
Whether using voltage or current for the drive
signal, they are linearly mapped to a 40°F to
240°F setpoint or a 0% to 100% valve position.
No scaling for these signals is provided
2.6.4 B.M.S. (PWM) IN
Not applicable to Water Heaters.
2.6.5 SHIELD
The SHIELD terminals are used to terminate any
shields used on sensor wires connected to the
unit. Shields must only be connected to these
terminals.
2.6.6 mA OUT
These terminals provide a 4 to 20 mA output that
can be used to monitor setpoint ( to 220°F),
outlet temperature ( to 245°F), or valve position
(0% to 100%). This function is enabled in the
Configuration Menu (Section 3, Table 3.4).
2.6.7 RS-485 COMM
These terminals are used for RS-485 MODBUS
serial communication between the unit and an
external “Master”, such as an Energy Manage-
ment System.
2.6.8 EXHAUST SWITCH IN
These terminals permit an external exhaust
switch to be connected to the exhaust manifold
of the boiler. The exhaust sensor should be a
normally open type switch (such as AERCO P/N
123463) that closes (trips) at 500°F.
2.6.9 INTERLOCKS
The unit offers two interlock circuits for
interfacing with Energy Management Systems
and auxiliary equipment such as pumps or
louvers or other accessories. These interlocks
are called the Remote Interlock and Delayed
Interlock (Fig. 2.10). The wiring terminals for
these interlocks are located inside the I/O Box
on the left side of the unit. The I/O Box cover
contains a wiring diagram which shows the
terminal strip locations for these interlocks
labeled REMOTE INTL’K IN and DELAYED
INTL’K IN. Both interlocks, described below, are
factory wired in the closed position.
NOTE:
Both the Delayed Interlock and Remote
Interlock must be in the closed position to
allow the unit to fire.
2.6.9.1 REMOTE INTERLOCK IN
The remote interlock circuit (REMOTE INTL’K
IN) is provided to remotely start (enable) and
stop (disable) the unit if desired. The circuit is
24 VAC and comes factory pre-wired closed
(jumped).
2.6.9.2 DELAYED INTERLOCK
The delayed interlock circuit (DELAYED INTL’K
IN) is typically used in conjunction with the
auxiliary relay described in paragraph 2.6.11.
This interlock circuit is located in the purge
section of the start string. It can be connected to
the proving device (end switch, flow switch etc.)
of an auxiliary piece of equipment started by the
unit’s auxiliary relay. The delayed interlock must
be closed for the heater to fire. If the delayed
interlock is connected to a proving device that