AERCO C-More Controls - Manual (Page 29)

C-MORE CONTROL PANEL OPERATION
only at the source end and must be left floating
(not connected) at the unit’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% firing rate. No scaling for
these signals is provided.
5.2.4 B.M.S. (PWM) IN
NOTE
Only BMS Model 168 can utilize pulse width
modulation, not the BMS II Model 5R5-384.
These terminals are used to connect the AERCO
Boiler Management System (BMS Model 168) to
the unit. The BMS Model 168 utilizes a 12
millisecond, ON/OFF duty cycle. This duty cycle is
Pulse Width Modulated (PWM) to control firing
rate. A 0% firing rate = a 5% ON pulse and a
100% firing rate = a 95% ON pulse.
5.2.5 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.
5.2.6 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 245°F), or fire rate (0%
to 100%). This function is enabled in the
Configuration Menu (Table 2-3).
5.2.7 RS485 COMM
These terminals are used for RS485 MODBUS
serial communication between the unit and an
external “Master”, such as a Boiler Management
System or other suitable device.
5.2.8 EXHAUST SWITCH IN
These terminals permit an external exhaust switch
to be connected to the exhaust manifold of the
unit. The exhaust sensor should be a normally
open type switch (such as AERCO Part No.
123463) that closes (trips) at 500°F.
5.2.9 INTERLOCKS
The unit offers two interlock circuits for interfacing
with Energy Management Systems and auxiliary
equipment such as pumps or louvers. These
interlocks are called the Remote Interlock and
Delayed Interlock. The wiring terminals for these
interlocks are located inside the I/O Box. The I/O
Box cover contains a wiring diagram (Figure 5-1)
which shows the terminal strip locations for these
interlocks which are 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 the Remote
Interlock must be in the closed position to allow
the unit to fire.
5.2.9.1 REMOTE INTERLOCK IN
The remote interlock circuit (REMOTE INTL’K IN)
is provided to remotely start (enable) and stop
(disable) the Boiler if desired. The circuit is 24 VAC
and comes factory pre-wired closed (jumpered).
5.2.9.2 DELAYED INTERLOCK IN
The delayed interlock circuit (DELAYED INTL’K IN)
is typically used in conjunction with the auxiliary relay
described in paragraph 5.2.11. 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 unit to fire. If the
delayed interlock is connected to a proving device
that requires time to close (make), a time delay (Aux
Start On Dly) that holds the start sequence of the unit
long enough for a proving switch to make can be
programmed. Should the proving switch not prove
within the programmed time frame, the unit will shut
down. The Aux Start On Dly can be programmed
from 0 to 120 seconds. This option is locate in the
Configuration Menu.
5.2.10 FAULT RELAY
The fault relay is a single pole double throw
(SPDT) relay having a normally open and normally
closed set of relay contacts that are rated for 5
amps at 120 VAC and 5 amps at 30 VDC,
resistive. The relay energizes when any fault
condition occurs and remains energized until the
fault is cleared and the CLEAR button is
depressed.
5.2.11 AUXILIARY RELAY CONTACTS
Each unit is equipped with a single pole double
throw (SPDT) relay that is energized when there is
a demand for heat and de-energized after the
demand for heat is satisfied. The relay is provided
for the control of auxiliary equipment, such as
pumps and louvers, or can be used as a unit
status indictor (firing or not firing). Its contacts are
rated for 120 VAC @ 5 amps resistive. Refer to
Figure 5-1 to locate the AUX RELAY terminals for
wiring connections.
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