MODE OF OPERATION
5-2
5.2 CONSTANT SETPOINT MODE
Constant setpoint mode is used when a fixed
header temperature is desired. Common uses of
this mode of operation include water source heat
pump loops, and indirect heat exchangers for
potable hot water systems or processes.
There are no external sensors necessary to
operate in this mode. While it is necessary to set
the desired setpoint temperature it is not
necessary to change any other temperature-
related functions. The unit is factory preset with
settings that work well in most applications. Prior
to changing any temperature-related
parameters, other than the setpoint, it is
suggested that an AERCO representative be
contacted. For a complete listing of factory
defaults and a description of temperature related
functions see Appendices A and E.
5.2.1 SETTING THE SETPOINT
The setpoint of the unit is adjustable from 40 to
200 degrees. To adjust the setpoint do the
following:
1. While in the Primary menu, scroll through it
until "Setp" is displayed.
2. Use the
⇑
and
⇓
arrow keys to set the
desired setpoint.
3. Press enter to accept any changes.
4. The unit is now ready to run.
5.3 4 -20mA REMOTE SETPOINT MODE
In this mode of operation, a 4-20mA signal, sent
by an energy management system, is used to
change the unit's setpoint. The 4mA signal is
equal to a 40-degree setpoint while a 20mA
signal is equal to a 220 -degree setpoint. This
mode of operation can be used to drive single as
well as multiple units.
An external interface board, located in the
control box, is used for this mode. The board is
factory configured and converts the 4 -20mA
signal to an RS-485 signal. The RS-485 signal is
in then used to communicate with the
temperature controller. The temperature must
have the following functions set as shown to
properly operate in the 4 - 20mA remote setpoint
mode.
MENU
FUNCTION
SETTING
Secondary
Lore
Re
Secondary
FUNC
Cont
Primary
Auto
ON
While it is possible to change the settings of
temperature related functions, the unit is factory
preset with settings that work well in most
applications. It is suggested that an AERCO
representative be contacted prior to changing
any temperature related function settings. For a
complete listing of factory defaults and a
description of temperature related functions see
Appendices A and E.
5.3.1 4-20mA REMOTE SETPOINT FIELD
WIRING
The only wiring necessary is the 4-20mA
external control wiring from the source, to
terminals 11 and 12 at the control box control-
wiring terminals. The signal must be floating
(ungrounded), and the wire used must be a two
wire shielded cable of 18 to 22 AWG. Polarity
must be observed and the shield must be
connected to terminal 1 at the control wiring
terminals. The source end of the shield must be
left floating and not connected. When driving
multiple units, each unit’s wiring must conform to
the above.
5.3.2 4-20mA REMOTE SETPOINT
STARTUP
Since this mode of operation is factory preset
and the setpoint is being externally controlled,
no startup instructions are necessary
.
To
operate the unit in manual mode, the
temperature controller must be taken out of
REMOTE and set to LOCAL, and Auto must be
set to OFF.
To set the unit to manual mode do the following:
1. Access the temperature controller’s
secondary menu.
2. Scroll through the menu until "lore" is
displayed.
3. Use the
⇑
and
⇓
arrow keys to set the
temperature controller to local. Press
ENTER to accept the change. The yellow
REM light, on the temperature controller,
should extinguish.
4. Access the Primary menu and scroll through
until “Auto” is displayed.
Summary of Contents for Benchmark G-00-711
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