iWorx® MPU2
505-009, Effective: June 30, 2015
19
© 2015 Taco Electronic Solutions, Inc.
• Alarm Conditions (IAQ Mode, Heat Failed On)
• Supply Air Temperature
Occupancy Mode
A remote device on the network (such as an LCI) provides the current occupancy mode. There are two modes of occu-
pancy: occupied and unoccupied.
In addition, the current occupancy mode is periodically retrieved from each of the zone controllers. If at least one zone
controller is currently in occupancy extension mode the occupancy mode is overridden to the occupied state.
The current occupancy mode can affect the operation of the economizer, fan and bypass damper.
Additionally the heating and cooling setpoints may be reset based on the greatest zone demand.
Setpoint Calculations
The supply air heating and cooling setpoints are programmable values. The effective setpoint is a calculated value
based on the current operating mode. The effective setpoint is set to the heating setpoint when the operational mode is
heating. It is set to the cooling setpoint when the operational mode is cooling.
Supply Air Setpoint Reset Curve
If the
Supply Temperature Setpoint Reset Curve
is enabled, the MPU2 keeps track of the differential between each
zone's space temperature and its temperature setpoint. The MPU2 selects the zone with the greatest differential and
uses that
Temperature Differential
to adjust the
Supply Temperature Setpoint
.
If the
Temperature Differential
is less than the
Temperature Differential Minimum
, then the
Supply Temperature Set-
point Low
will be used. If the
Temperature Differential
is greater than the
Temperature Differential Maximum
, then the
Supply Temperature Setpoint High
is used.
When the
Temperature Differential
is between the
Temperature Differential Maximum
and
Temperature Differential
Minimum
, the
Supply Temperature Setpoint
is linearly interpolated between the
Supply Setpoint High
and
Supply Set-
point Low
.
