AERCO Control System (ACS) - Manual (Page 58)

MC2: 04/23/13 Page 58 of 144
GF-131
AERCO Control System (ACS)
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, New York 10913 • Phone: 800-526-0288
Installation, Operation, and Maintenance Manual
OMM-0081_0D
3.10.2 BOOST MAX TIMER
This setting is the maximum amount of time that the boost input should be continually activated.
It should be assumed that the switch is broken if the boost input remains activated longer than
the time entered in this setting.
If Interlock 2 remains activated for longer than the BOOST MAX TIMER setting, the boost will be
de-activated and the fault message “BOOST DISABLED” will be displayed and the fault relay
activated. The fault message may be cleared by cycling the boost input (Interlock 2) or by
pressing the “clear” key. The default setting for this is OFF.
3.11 TUNING MENU
The TUNING MENU options are used to select PID (Proportional Integral Derivative) control
functions incorporated in the ACS. These functions govern temperature control and response of
the ‘ACS to the boiler system. Since each system is different, these PID controls can tune the
ACS to the characteristics of your specific installation. The factory defaults preset by AERCO
work well for most applications. In instances when there is a large error between the setpoint
and the actual supply water temperature, the ACS may appear to require PID tuning. However,
it is best to observe ACS operation over a period of time prior to making any PID changes.
Contact AERCO, or an AERCO representative, prior to making any PID setting changes.
The TUNING MENU options include Proportional Bandwidth, Integral Gain, Derivative Gain and
Header Temperature Deadband.
3.11.1 PROPORTIONAL BND
The Proportional Bandwidth (degrees) represents the immediate response to a setpoint error.
This value is the temperature deviation from setpoint for which a 100% output change is
desired. This is a part of the PID output calculation in the ACS.
For instance, proportional band of 50°F is chosen. The header temperature setpoint is 180°F
and the actual incoming supply water temperature is 130°F. This is a 50°error and the following
is true:
Temp. Error X 100 = Firing Rate in %
Prop Bandwidth
Therefore:
50 X 100% = Firing Rate
50
1 X 100 = 100 % Firing Rate
With an error of 30° and a bandwidth of 50, the following would be true:
30/50 X 100 = .6 X 100 = 60% Firing Rate.
3.11.2 INTEGRAL GAIN
The Integral Gain (repeats/min) responds to the setpoint error over time. Integral references the
proportional band error signal and sums itself with respect to the period of time the error exists.
Based on the previous example, if the integral gain is 0.15 repeats/minute at a firing rate of 60%
and a temperature error exists for one minute, then the following is true:
(0.15 reps/min.) x (60% firing rate) = 9% actual firing rate
60% firing rate +9% firing rate = 69% firing rate
Temp. Error
Prop Bandwidth