AERCO KC1000 Water Heater July 2011 - Manual (Page 15)

INSTALLATION
2-7
Wiring for these features can be accomplished
in the I/O Box behind the left side panel (Figures
2.10 and 2.11). The I/O Box is common to both
KC1000 water heaters and boilers. While some
of the inputs and outputs are common to both
water heaters and boilers, some are not
applicable to both. These are noted in the
following paragraphs.
GAS SHUT-OFF VALVE
I/O BOX
BLOWER
Figure 2.10
Input/Output (I/O) Box Location
CAUTION!
DO NOT make any connections to the I/O
Box terminals labeled “NOT USED”.
Attempting to do so may cause equipment
damage.
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 moni-
toring 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 is located 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 (Remote Setpoint Mode) of the heater.
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 set-
point 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
PMC Board located inside the Control Box.
Contact the AERCO factory for information on
setting DIP switches.
All supplied signals must be floating (unground-
ed) signals. Connections between the source
and the Heater’s I/O Box must be made using
twisted shielded pair of 18–22 AWG wire such
as Belden 9841(see Figure 2.11). Polarity must
be maintained and the shield must be connected
only at the source end and 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% air/fuel 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 ( 40°F to
240°F), outlet temperature (30°F to 240°F), or
air/fuel valve position (0% to 100% open). 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 serial
communication between the unit and an external
“Master” such as an Energy Management
System or other suitable device.
2.6.8 EXHAUST SWITCH IN
These terminals permit an external exhaust
switch to be connected to the exhaust manifold
of the heater. The exhaust sensor should be a
normally open type switch (such as AERCO P/N
123463) that closes (trips) at 500 o F.
2.6.9 INTERLOCKS
The unit offers two interlock circuits for inter-
facing 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
(Figure 2.11). 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