AERCO BMS II BOILER - Manual (Page 59)

PROGRAMMING BMS II
4-9
Entering Load Start Percent (Required Only for Modulex Installations)
If the boiler plant contains Modulex boilers, the LOAD START PCT option in the Calibration Menu must
be entered. This option should be set 2% below the BLR START LEVEL set in the Configuration Menu.
Proceed as follows:
1. Press the MENU key until CONFIGURATION MENU appears in the display.
2. Scroll through the menu using the
▲ or ▼ arrow key until LOAD START PCT appears in the display
along with the current setting for this option (default = 1%).
3. Refer to Appendix I to determine the appropriate BLR START LEVEL for the Modulex Boiler.
4. Press the CHANGE key to change the displayed value. The display will switch to a reverse video
format.
5. Using the
▲ and ▼ arrow keys, set the LOAD START PCT to 2% below the BLR START LEVEL.
6. Press the ENTER key to store the changed percentage. The reverse video display will revert to the
normal VFD display format.
7. The BMS II is now fully programmed for operation in the Outdoor Reset Mode with Modulex Boilers.
4.5 “TEMP AND LOAD” OPTION
The boiler plant, and the System Start Relay, can be programmed to start based on either, or both, an
outdoor temperature and/or load demand criteria. When the SYS START OPTION is set to TEMP ONLY,
the outdoor temperature is the only criteria used to activate the system. In this case the system, and the
System Start Relay, will activate when the outdoor temperature falls below the SYS START TEMP
setting. If no outdoor sensor is installed, the system (and the System Start Relay) will always be activated
in this case. The system will shut down and the System Start Relay deactivated when the outdoor
temperature rises above the SYS START TEMP setting.
If the SYS START OPTION is set to TEMP AND LOAD, the system (and the System Start Relay) will
start when the outdoor temperature is below the SYS START TEMP setting and the load demand
(PERCENT OF LOAD) is at or above the LOAD START PCT (in Calibration Menu). The PERCENT OF
LOAD display in the Operating Menu will show 0% until both of these criteria are satisfied. The system will
shut down and the System Start Relay deactivated if either the outdoor temperature rises above the SYS
START TEMP or the PERCENT OF LOAD falls below the LOAD STOP PCT. If no outdoor sensor is
installed, the system (and the System Start Relay) will activate when the PERCENT OF LOAD is at or
above the LOAD START PCT. The system will shut down when the PERCENT OF LOAD falls below the
LOAD STOP PCT.
4.6 “START ENABLED” OPTION
The BMS II can be used to turn on and prove a device such as a fresh air damper, gas booster or the flow
of a local pump before ramping up the output. With SYS INTLK CONFIG (Configuration Menu) set to
START ENABLED, the BMS II will allow 30 seconds after it activates the System Start Relay before
proving the selected interlock (such as SYS START INTLK) and ramping up the output. The System Start
Relay can activate the device and the dry-contact proving switch of the device, or devices can be wired to
one or both interlocks.