Valent Controls IOM 50 IOM-C1-0616
Part Number 474626
Supply Fan Reaction Speed
Determines how fast the supply fan will react to
a change in duct pressure or space pressure
(depending on unit configuration). Allows some
PID tuning should the supply fan “hunt.”
Supply Fan Speed
Displays the speed of the supply fan as a
percentage of design speed. The rooftop unit
includes a variable frequency drive (VFD) for the
supply fan motor. In constant volume operation,
the speed of the fan remains constant at the
defined speed (50-100%, adjustable). At 100%,
the fan speed is equal to the design frequency,
in Hz. The speed of the supply fan may be
slowed for constant volume operation by
adjusting the supply fan speed in the controller
(50-100%). The minimum speed must not be
less than 50% of the design flow to ensure
proper heating and cooling operation.
For space static or variable air volume (VAV)
applications, the speed of the fan is
automatically determined by the controller (50-
100%). This is wired to AO4 on the DDC1 I/O
module.
Supply Fan Status
Reflects the status of the differential pressure
switch for the supply fan (U8 on the DDC1 I/O
module). When the input contacts are closed,
the supply fan is running. When the input
contacts are open, the supply fan is off.
Supply Setpoint Calculated
If the system does not have a space
temperature sensor, or if one is installed and the
point Force Supply is set to True, then the unit
will control the supply air temperature to this
setpoint.
Supply Temperature
The supply air temperature is measured by the
field-installed (factory provided) sensor located
in the supply duct immediately downstream of
the rooftop unit. The sensor is an IOU Type III
thermistor that is wired to U1on the DDC1 I/O
module.
System Enable
Must be On for normal unit operation. When
system enable is Off, the unit is completely
disabled and will not operate.
Timed Override Duration
When the override button on the space sensor is
pressed, this is the amount of time that the unit
will be placed into occupied mode. When the
override expires, the unit returns to its prior state
or Auto.
Unit Schedule
This is a 24-hour standalone schedule that is
programmable from either the LCD interface or
the Universal Maintenance Tool software.
Occupied and Unoccupied time can be set with
minute increments. Defaults to 24/7 Occupied
operation.
Unoccupied Outdoor Air Damper Minimum
During unoccupied operation, this is the position
of the outdoor air damper on recirculation units,
as a percentage of fully open (100%).
Unoccupied Space Cooling Setpoint
This is the temperature at which cooling is
enabled during unoccupied operation.
Unoccupied Space Heating Setpoint
This is the temperature at which heating is
enabled during unoccupied operation.
Unoccupied Space Relative Humidity Setpoint
This is the Relative Humidity at which
dehumidification is enabled during unoccupied
operation.
Unoccupied Supply Fan Offset
This is the speed at which the supply fan VFD
will run when unoccupied, as a percentage of full
speed (100%). When the unit is started in night
heating, cooling, or dehumidification, the supply
fan runs at this reduced speed. If the supply fan
is controlling to maintain a duct or space static
pressure, CO2, or is configured for a remote fan
input, the fan speed is not reduced.
Water Source Heat Pump Cold Start Duration
This defines the duration of cold start mode,
where the compressors will ramp into full
operation to allow the unit to start in very cold
weather.
Water Source Heat Pump Cold Start Enable
Temperature
Cold start mode is enabled when the outdoor air
temperature is equal to or less than this setpoint.
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