AERCO BMS II BOILER - Manual (Page 41)

OPERATION
3-9
HDR LOW LIMIT
The HDR LOW LIMIT menu option sets the minimum temperature setting allowed for the Header Setpt.
This setting also defines the 4 mA temperature equivalent when operating in the Remote Setpoint Mode
using a 4 – 20 mA signal. The setting range is from 40°F to the HDR HIGH LIMIT. (Default = 40°F).
INTERNAL SETPT
The INTERNAL SETPT temperature is the HEADER SETPT used when CONSTANT SETPT is selected
for the HEADER SET MODE or when the BMS II operates in the Failsafe Mode and CONSTANT SETPT
is selected as the FAIL SAFE MODE setting in the Configuration Menu.
RESET RATIO
This menu option is displayed only if the HEADER SET MODE is set to OUTDOOR RESET. The RESET
RATIO option setting defines the ratio of the increase in Header temperature with respect to each degree
decrease in Outdoor temperature starting from the Building Reference Temperature (BLDG REF TEMP).
The Reset Ratio is adjustable from 0.3 to 3.0. (Default = 1.2). The Reset Ratio Charts provided in
Appendix D are suitable for most applications. However, if a special reset schedule is desired, the
calculation method described in Appendix D must be used.
BLDG REF TEMP
The BLDG REF TEMP menu option is only displayed when the HEADER SET MODE is set to
OUTDOOR RESET. This option is used to set the Building Reference Temperature (BLDG REF TEMP)
to the desired value from 40°F to 220°F. (Default = 70°F).
REMOTE SIGNAL
The REMOTE SIGNAL menu option is only displayed when the HEADER SET MODE is set to REMOTE
SETPT. When displayed, this option is used to select the controlling remote signal: to 4 – 20 mA or
MODBUS. (Default = 4-20 mA)
OFFSET ENABLE
The OFFSET ENABLE menu option is used to turn ON, or turn OFF the Setpoint Temperature Offset
feature. (Default = OFF)
Offset Menu Options
The Field Adjust Menu contains a series of menu options which permit an offset schedule to be set up for
a 7-day period (Sunday through Saturday). For each day (Sunday – Saturday), these options include:
• OFFS TEMP [Setpoint Offset Temperature (-50°F to +50°F)]
• ON HOUR (00 to 23)
• ON MINUTE (00 to 59)
• OFF HOUR (00 to 23)
• OFF MINUTE (00 to 59)
Normally, if an Offset Schedule is used, it is controlled automatically using the set-up procedures
described in the paragraph titled “Setting Up An Offset Reset Schedule” However, if desired, the header
offset can be controlled manually by connecting a switch across the SET BACK wiring terminals 13 and
14 as shown in the wiring diagram in Appendix E. If a manual offset is used, refer to the paragraph titled
“Manual Offset”.