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The following conditions must be true in order for the Heating
Setpoint OA Reset algorithm to run:
•
The
preconditions
for
previously) have been met.
•
The module has a valid Outdoor Air Temperature.
•
Heating Setpoint OA Reset is Enabled.
HEATING CONTROL MODES
The following control modes are available for heating operation.
These modes may be selected by the installing technician, or by an
operator of sufficient access rights using one of the available man
machine interfaces (BACview, Field Assistant, or i-Vu Open
Server). See the Controls Configuration sections for additional
instructions.
Manual Heat
Configuring the Control Mode Selection for Manual Heat places
the control in a heating only configuration. The module will
operate as described in the Heating section while configured for
Manual Heat. The Heating Setpoint OA Reset function is
available provided the associated preconditions (described
previously) are met.
When the Control Mode Selection is set to Manual Heat, the
lockout temperature (OAT, SPT, or T1) is overridden, even when
the input is available. The control will operate as required to
maintain the Hot Water Supply Temperature setpoint, regardless
of the any previously configured lockout temperature.
The following conditions must be true in order for the heating
algorithm to run in the Manual Heat control mode:
•
Control Mode Selection is set to Manual Heat.
•
Heat Enable is set to Enable.
•
Unit is occupied (see Occupancy Section above).
•
Load water temp is below the Hot Water Supply Setpoint.
OAT
Configuring the Control Mode Selection for OAT sets the control
to change modes between heating and cooling automatically
based on the Outdoor Air Temperature (OAT). The control will
compare the OAT to the configured lockout temperatures for
heating and cooling and select the appropriate operating mode. A
valid outdoor air temperature reading (hardware or network) is
required for this mode. Once enabled, equipment control is as
described for heating and cooling.
When conditions require heating, the module will operate as
described in the Heating section. The Outdoor Air Hot Water
Supply setpoint reset function is available provided its associated
preconditions (described previously) are met.
The following conditions must be true in order for the heating
algorithm to run in the OAT control mode:
•
A valid Outdoor Air Temperature is present.
•
Control Mode Selection is set to OAT.
•
Heat Enable is set to Enable.
•
Unit is occupied (see Occupancy Section above).
•
The OAT is less than the Heating lockout temperature
setpoint.
•
Cool mode is not active and the compressor time guard has
expired.
•
The Changeover time guard has elapsed.
•
Load water temp is below the Hot Water Supply Setpoint.
SPT
Configuring the Control Mode Selection for SPT sets the control
to change modes between heating and cooling based on the Space
Temperature sensor located in the space or return air plenum
(SPT). The control will compare the SPT to the configured
lockout temperatures for heating and cooling and select the
appropriate operating mode. A valid space temperature reading
heating
operation
(described
(hardware or network) is required for this mode. Once enabled,
equipment control is as described for heating and cooling.
When conditions require heating, the module will operate as
described in the Heating section. The Outdoor Air Hot Water
Supply setpoint reset function is available provided its associated
preconditions (described previously) are met.
The following conditions must be true in order for the heating
algorithm to run in the SPT control mode:
•
A valid SPT is present.
•
Control Mode Selection is set to SPT.
•
Heat Enable is set to Enable.
•
Unit is occupied (see Occupancy Section above).
•
The SPT is less than the Heating lockout temperature
setpoint.
•
Cool mode is not active and the compressor time guard has
expired.
•
The Changeover time guard has elapsed.
•
Load water temp is below the Hot Water Supply Setpoint.
System T1 Temp
Configuring the Control Mode Selection for System T1 Temp sets
the control to change modes between heating and cooling based
on a network temperature. The control will compare the network
temperature to the configured lockout temperatures for heating
and cooling and select the appropriate operating mode. The
System T1 Temperature network input object must be addressed
to read the desired temperature and communicating for this mode.
Once enabled, equipment control is as described for heating and
cooling.
When conditions require heating, the module will operate as
described in the Heating section. The Outdoor Air Hot Water
Supply setpoint reset function is available provided its associated
preconditions (described previously) are met.
The following conditions must be true in order for the heating
algorithm to run in the System T1 Temp control mode:
•
A valid network T1 Temperature is present.
•
Control Mode Selection is set to T1.
•
Heat Enable is set to Enable.
•
Unit is occupied (see Occupancy Section above).
•
The T1 Temperature is less than the Heating lockout
temperature setpoint.
•
Cool mode is not active and the compressor time guard has
expired.
•
The Changeover time guard has elapsed.
•
Load water temp is below the Hot Water Supply Setpoint.
Demand Limit
The W2W control has the ability to accept a demand limit signal
from the network. The demand limit function provides a means
for W2W controls installed as part of an i-Vu Open system to have
their heating and chilled water setpoints expanded (lowered and
raised respectively) to lower the equipments electricity
consumption. The amount of setpoint adjustment for each of the
three demand levels is user adjustable for both heating and
cooling. The configured demand level values are cumulative, as
such a level 3 demand limit incorporates the reset values of
demand level 1 + demand level 2 + demand level 3.
If both outdoor air setpoint reset and demand level limiting are
active simultaneously, the reset value applied will be the greater of
the two individual reset functions in effect but NOT the
cumulative total of both.
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