User Manual

RECON Water Heaters Installation, Operation & Maintenance Manual
CHAPTER 2 – INSTALLATION
OMM-0103_0A AERCO International, Inc.  100 Oritani Dr.  Blauvelt, NY 10913 Page 35 of 178
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2.12.9 RS485 COMM Terminals
The RS485 communication terminals (+, GND, & -) are used when the RECON Water Heaters
are being controlled by an Energy Management System (EMS) or the C-More Water Heater
Management (WHM) system using Modbus (RS485) communication. The WHM software
required to control up to 8 AERCO RECON Water Heaters is included in the C-More Control
System used with each RECON unit.
2.12.10 RS232 COMM Terminals
These terminals are used only by factory-trained personnel to monitor OnAER communications
via a portable computer.
2.12.11 VFD/BLOWER Terminals
These terminals (0-10 & AGND) send an analog signal to control the blower speed. When any
of the 4-20mA options is selected for the Analog Outputs (section 2.12.8, above), the output
from the VFD/Blower terminals is disabled.
2.12.12 INTERLOCK Terminals
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 (REMOTE INTL’K IN and DELAYED INTL’K IN in
Figure 2-14). Both interlocks, described below, are factory wired in the closed position.
NOTE
Both the Remote Interlock and Delayed Interlock must be in the
closed position for the unit to fire.
2.12.12.1
REMOTE INTL’K Terminals
The remote interlock circuit 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).
2.12.12.2
DELAYED INTL’K Terminals
The delayed interlock is typically used in conjunction with the Auxiliary Relay Contacts,
described in section 2.12.14, below. 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
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 (close) 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
located in the Configuration Menu (Chapter 3).
2.12.13 FAULT RELAY Terminals
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. The
relay energizes when any fault condition occurs and remains energized until the fault is cleared
and the CLEAR button is depressed. The Fault Relay connections are shown in Figure 2-14.