Data Aire dap4 User Manual page 41

MENU J – FACTORY SETTINGS (factory level) continued
Note: The Fan Delta Tuning PID screen is only displayed on IRDX models when
fan mode is set to modulate to maintain Delta Temp.
The dap4 uses a selectable stepped method or proportional, integral and
derivative algorithm (P, P+I or PID) to maintain the delta temperature to the delta
temperature set point (Shown in the set points menu). The difference between the
delta set point and the actual measured delta temperature is called the error.
Delta Temp: This is the display of the delta temperature, which is the difference
between the Return and Discharge air temperatures.
Control: Selection of the algorithm used: Stepped, Proportional (P), Proportional
and Integral (P+I) and Proportional Integral Derivative (PID). Note: Stepped control
is similar to Proportional control except changes in fan speed are made up of ten
steps rather than much finer increments.
Band: This setting determines the sensitivity of the algorithm. The smaller the
band, the more the algorithm will try to correct the error. If the band setting is too
low, the system will oscillate by being over-responsive. If the band setting is
too high, fan speed may lack responsiveness. Ideally, the band setting
should be as low as possible without causing oscillation. Range of adjustment
is 1.0 to 99.0°F with a default of 50.0°F.
Integration Time: (Only shown when control set to P+I or PID). Used to slowly
shift the fan speed level as a result of error. The h ighe r Integral time setting,
the slower the fan speed level will be shifted. If the Integral time is set too low
the f a n sp e e d level could ch a n g e quickly, causing oscillation. A setting of 0s
(default) puts the algorithm in a proportional only mode. Range of adjustment is 0
to 999s.
Derivative Time: (Only shown when control set to PID). Causes a sudden change
in fan speed to correct the error as a result of a quick change in measured air flow.
Typically, the derivative setting is about a sixth of the Integral time setting.
Fan Modulation: Indicates the percentage of fan speed demand.
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