AERCO BMK 3.0 LN Nat. Gas APRIL 2009 - Manual (Page 40)

MODE OF OPERATION
7. Press the CHANGE key. The display will
begin to flash.
8. Use the ▲ and ▼ arrow keys to select the
desired Building Reference Temperature.
9. Press ENTER to save any changes.
10. Next, scroll through the Configuration Menu
until the display shows Reset Ratio.
11. Press the CHANGE key. The display will
begin to flash.
12. Use the ▲ and ▼ arrow keys to select the
Reset Ratio determined in step 5.
13. Press ENTER to save the change.
Refer to paragraph 3.3 for detailed instructions
on menu changing.
5.3 CONSTANT SETPOINT MODE
The 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.
No external sensors are required 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
descriptions of temperature-related functions
and their factory defaults, see Appendices A and
E.
5.3.1 Setting the Setpoint
The setpoint temperature of the unit is
adjustable from 40°F to 240°F. To set the unit
for operation in the Constant Setpoint Mode, the
following menu settings must be made in the
Configuration Menu:
MENU OPTION SETTING
Boiler Mode Constant Setpoint
Internal Setpt Select desired setpoint
using ▲ and ▼ arrow
keys (40°F to 240°F)
Refer to paragraph 3.3 for detailed instructions
on changing menu options.
5.4 REMOTE SETPOINT MODES
The unit’s setpoint can be remotely controlled by
an Energy Management System (EMS) or
Building Automation System (BAS). The Remote
Setpoint can be driven by a current or voltage
signal within the following ranges:
4-20 mA/1-5 Vdc
0-20 mA/0-5 Vdc
The factory default setting for the Remote
Setpoint mode is 4 - 20 mA/1 - 5 Vdc. With this
setting, a 4 to 20 mA/1 to 5 Vdc signal, sent by
an EMS or BAS, is used to change the unit's
setpoint. The 4 mA/1V signal is equal to a 40°F
setpoint while a 20 mA /5V signal is equal to a
240°F setpoint. When a 0 to 20 mA/0 to 5 Vdc
signal is used, 0 mA is equal to a 40°F setpoint.
In addition to the current and voltage signals
described above, the Remote Setpoint mode
can also driven by a RS485 Modbus Network
signal from an EMS or BAS.
The Remote Setpoint modes of operation can be
used to drive single as well as multiple units.
NOTE
If a voltage, rather than current signal is
used to control the remote setpoint, a DIP
switch adjustment must be made on the
PMC Board located in the Control Panel
Assembly. Contact your local AERCO
representative for details.
In order to enable the Remote Setpoint Mode,
the following menu setting must be made in the
Configuration Menu:
MENU OPTION SETTING
Boiler Mode Remote Setpoint
Remote Signal 4-20mA/1-5V,
0-20mA/0-5V, or
Network
Refer to paragraph 3.3 for detailed instructions
on changing menu options.
5-2