UM-15094500-AA0
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BACnet controlled
– In this control scheme, the built-in thermostat algorithm can be
bypassed, and the thermostat can be controlled over the BACnet network with
commands from the supervisor device. The logic executing in the supervisor (such as
Niagara or Sedona logic) can control the thermostat over the BACnet network. To put
the thermostat in BACnet network control mode, use the Lock [
AV18
] object bit 9:
Control DOs by thermostat algorithm “0” (default) or BACnet supervisor “1” (add
decimal=512).
Cool Only
and
Heat Only
modes
(nullified/disabled in firmware)
are control types listed
in the BACnet object and Engineering Menu object but are not available for use.
Control type is only configurable by the installer using Engineering Mode Menu or
BACnet supervisor. The installer must decide the control type suitable for the
application, set it to a static value, or program the BACnet supervisor to change the
control type automatically. The default control type is set to Cooling or heating
with
Auto Changeover. Manual Changeover can be used to prevent excessive automatic
changeover between cooling and heating system modes.
Algorithm
•
A PID adaptive control algorithm is applied to minimize overshoot, in addition to
proportional band (Stage Width) and derivative (Differential) calculation.
•
When the thermostat is active (either the heating or cooling stage is on), a
“Working (
)” icon will be shown on the LCD. Stage 1 will show icon (
).
Stage 2 will show icon (
) 3rd stage heat will show icon (
).
System Mode
•
The default control type, multi-staged cooling and heating with automatic
changeover, allows the thermostat to operate as stand-alone. Manual
Changeover allows restriction of mode selection to Cool only or Heat only where
necessary. Control Type can be selected in (
tyPe
) or [
MSV7
].
•
For manual changeover control, cooling or heating system modes can be selected
by pressing the MODE button or using a BACnet command to object [
MSV1
]. In
application where user control needs to be limited, the lock button function can
be used to disable MODE button.
•
Occupied Cooling [
AV0
] and Heating [
AV3
] set points and Unoccupied Cooling
[
AV8
] and Heating [
AV9
] setpoints can be set individually. Minimum deadband
[
AV7
] can be programmed as well.
Short On/Off (Minimum On/Off time) and Maximum cycles per Hour
•
There are short on/off (minimum off time and minimum on time of stage
engagement) and maximum cycles per hour protection for cooling and heating
mode(E29, E31, E54, E55; AV24, AV26, AV46, AV47).
•
Short on/off time (in seconds) will check minimum on time and minimum off time