AERCO BMS 168 - Manual (Page 43)

Section 5 ______________________________
Programming
the BMS Mode
of Operation
__
Prior to programming, the BMS must be
mounted and all required wiring completed.
In addition, all connections should be
checked for accuracy. The BMS is now
ready to be programmed for the desired
mode of operation of the boiler plant. The
steps for programming will vary somewhat,
depending on whether the Indoor/Outdoor
Reset, Remote Setpoint or Constant
Setpoint operating mode is selected.
5.1 I
NDOOR
/O
UTDOOR
R
ESET
M
ODE
The Indoor/Outdoor Reset mode is based
on outside air temperature. The header
supply water temperature will vary up or
down in accordance with outside air
temperature. This mode requires that, as a
minimum, a System Start Temperature
(SYS.START RELAY), Building Reference
Temperature (BLDG REF. TEMP) and
Reset Ratio be programmed into the BMS.
This data is based on the degree days for
your geographic area. An outdoor air sensor
MUST be installed when operating in this
mode (refer to paragraph 3.3.2).
5.1.1 Selecting Indoor/Outdoor Reset
Mode
To select Indoor/Outdoor Reset mode,
perform the following steps:
1. Press the CONFIG SYS key to enter the
System Configuration mode. The
CONFIG SYS key LED will illuminate.
2. Place SYSTEM CONFIGURATION
OVERLAY on the BMS front panel.
3. Press the HDR SET MODE key once.
HEADER SET MODE is displayed with
the present mode selection.
4. While observing the display, toggle the
HDR SET MODE using the ▲ or ▼ key to
IN/OUTDOOR RESET.
5. Press the CONFIG SYS key to exit the
System Configuration mode. The key
LED will go off.
6. Remove the SYSTEM CONFIGURA-
TION OVERLAY from the front panel.
5.1.2 Entering System Start
Temperature
The system start temperature is the outside
temperature at which the boiler plant begins
to operate. AERCO presets the system start
temperature at 70°F. However, temper-
atures from 32 to 120°F can be selected
using the ▲ and ▼ arrow keys on the
keypad. Proceed as follows to enter the
system start temperature:
1. Press FIELD ADJ mode key. Verify that
the FIELD ADJ key LED illuminates.
2. Press the SYS START TEMP key.
3. Using the ▲ and ▼arrow keys, select
the desired Start Temperature for the
boiler plant.
5.1.3 Determining Reset Schedule
There are two possible variables that must
be considered when determining reset
schedule; reset ratio and building reference
temperature. There are two methods for
determining reset ratio. The first method
uses the charts in Appendix B. This method
is suitable for most installations. However, if
a special reset schedule is desired for
reheat or other purposes, the calculation
method must be used. In this method, both
reset ratio and building reference
temperature must be calculated. See
Appendix B for further instructions
concerning both of these methods.
5-1