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1
Service
BMS Set Point at Minimum Volts
This parameter is visible only when the BMS Mode is set to
SETPOINT. The value of this parameter determines the set
point when the voltage on the 0 - 10V BMS input is equal to
or less than the BMS Volts at Minimum parameter value.
BMS Set Point at Maximum Volts
This parameter is visible only when BMS Mode is set to
SETPOINT. The value of this parameter determines the set
point when the voltage on the 0 - 10V BMS input is equal to
or more than the BMS Volts at Maximum parameter value.
BMS Volts to Enable
When BMS is set to ACTIVE, the boiler may be enabled
either through the ENABLE input, or by the voltage on the
0 - 10V BMS input (see BMS Tstat Enable Mode below). If
enabled through the voltage on the 0 - 10V BMS input, the
value of this parameter determines the voltage at which the
boiler becomes enabled.
Differential to Stop BMS Demand
When BMS is set to ACTIVE, and the boiler is enabled
through the voltage on the 0 - 10V BMS input, the voltage
must go below the BMS Volts to Enable value by this amount
in order to end the demand.
BMS Tstat Enable Mode
In order to use the ENABLE input to enable the boiler, this
parameter must be set to ACTIVE. To use the voltage on the
0 - 10V BMS input to enable the boiler, this parameter must
be set to INACTIVE.
22
BAS
BAS Active / Inactive
The boiler is capable of being monitored and/or controlled
by a Building Automation System (BAS) through either a
ModBus RTU or BACnet MS/TP communication system.
In addition, it can communicate through a BACnet TCP/IP
system with the use of an optional gateway. See the Crest
ModBus Manual (100161012) for details on the points that
are available. If the boiler is to be monitored by the BAS
system, the BAS Active / Inactive parameter should be set to
INACTIVE. If the boiler is to be controlled through a BAS
system, the BAS Active / Inactive parameter must be set to
ACTIVE.
BAS Out of Order Timer
When the boiler is being controlled by the BAS system,
the commands it sends to the boiler must be refreshed
periodically. If the boiler does not receive a command for
too long, the boiler will revert to its local readings (e.g.,
enable input, temperatures, etc. ) until a new command is
received from the BAS system. For most commands, this
timeout is fixed at 10 minutes. Certain commands (0 - 10V
BMS voltage, system supply temperature, system return
temperature, and tank temperature) can change quickly, so
they need to be refreshed more often. The timeout for these
commands is controlled by the BAS Out of Order Timer.
Service Manual
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