Advanced Microprocessor with Graphics Control Setup
25
4.7.2 Select Options
The following table is a list of features that should match the options installed with your unit and
should not need to change during normal operation.
4.7.3 Calibrate Sensors
The temperature and humidity sensors can be calibrated by selecting this menu item. “SENSOR”
shows the actual sensor reading or raw reading. “CALIBRATED” shows the sensor reading after the
calibration offset has been added. The temperature sensor can be calibrated ±5 degrees Fahrenheit
and the humidity sensor can be calibrated ±10% RH. When calibrating the humidity sensor, the value
shown will always be % RH, even though absolute humidity control may be selected. If absolute
humidity control is selected, the Normal Status Display
will
display the
adjusted
reading and may
not agree with the relative humidity reading displayed while in calibration.
4.7.4 Calibrate Valve Actuator
For systems that use a valve actuator for chilled water or glycol cooling, the actuator timing may be
calibrated or adjusted through this feature. This is the time it takes for the valve to travel from full
closed to full open. It is programmable from 0 to 255 seconds. The factory default time is 165 seconds
and should not be changed unless the actual valve travel time is not correct. The full valve travel time
is used by the control to determine the appropriate valve position. For example, if the valve travel
time is 165 seconds and 50% cooling is being called for, the valve will open for 83 seconds to achieve
50% open. To change the valve travel time, first enter the “CALIBRATE VALVE ACTUATOR” screen.
The display will show the present period used by the control for valve actuator full travel. Press
ENTER and adjust the time using the UP/DOWN arrows. When the correct time is displayed, press
ENTER to store the new time in memory.
4.7.5 Select Control Algorithm
The type of system control method used by the microprocessor can be selected from the front panel.
The default setting is
INTELLIGENT,
which approximates the actions that a human operator would
take to maintain precise, stable control. The control logic uses Artificial Intelligence techniques
including “fuzzy logic” and “expert systems” methods to maintain precise, stable control and increase
reliability by reducing component cycles.
PROPORTIONAL
is a standard control method that uses
one gain factor (temperature sensitivity adjustment).
TUNABLE PID
(Proportional, Integral, and
Derivative) uses three gain factors selected by the operator. PID allows precision tuning, but requires
an experienced operator and seasonal adjustments. Note that if PID is selected, it is used for temper-
ature control while humidity will continue to use Proportional Control. For chilled water units with
the optional Variable Speed Drive, Intelligent is required for proper operation. Refer to
5.0 -
Response by Control Type—Advanced Microprocessor Controls
for more details on types of
control.
Table 10
Select options
Option
Selection
Heating
Yes or No
Humidifier
Yes or No
Dehumidifier
Yes or No
Humidifier Pan
Small or Large
Hot Gas Reheat
Yes or No
Heat Stages*
2 or 3
Dehumidification Stages
1 or 2
*If heat stage is set to 2 on a chilled water unit, the
reheat 3 output is energized on a call for
dehumidification.
