EVAPCO eco-Air Series, User Manual

Page: 26 / 39

26
Controller User Manual
Graph 1
The 5°F and 10°F temperature regulation band samples.
If equipped with a precooling system, the screen shown in Figure 33 will be accessible. The parameters contained in this screen are
used to determine various temperature setpoints that will active the precooling system, along with timers to ensure hysteresis
protection of the system.
Precooling system parameters.
To help prevent the precooling system from freezing, a minimum ambient operating temperature must be satisfied for the precooling
system to be active. If the ambient temperature falls below the minimum specified temperature, the precooling system will deactivate
and will not become active again until the ambient temperature rises above the minimum specified temperature plus the specified
difference. For example, using the values shown in Figure 33, if the precooling system is operating and the ambient temperature falls
below 40.0°F, the precooling system will turn off and will not activate again until the ambient temperature reaches 45.0°F.
Note that
all pipework that is susceptible to freezing must be heat traced in order to avoid damage.
Parameter Description Default
Setpoint The minimum temperature at which the precooling system may
operate. 40.0°F
Differential Determines the ambient temperature above the minimum allowable
temperature setpoint at which the precooling system may activate. 5.0°F
Table 13
A description of the pre-cooling system minimum operating ambient temperatures.
In order to prevent minor fluctuations in the process temperature from quickly cycling the precooling system on and off, an increase
and decrease timer is used. For example, using the values shown in Figure 33 and assuming a process setpoint temperature of
75.0°F, the process temperature must remain above 75.0°F for 15 seconds before the precooling system will activate. Conversely, if
the precooling system is active, the process temperature must remain below 75.0° for 15 seconds before the precooling system
deactivates.
Parameter Description Default
Stage #1
Increase Time
The amount of time that the process temperature must remain above the process setpoint
before the first precooling stage activates. 15 seconds
Stage #1
Decrease Time
The amount of time after the preceding stages have disabled that the process temperature
must remain below the process setpoint before the first precooling stage deactivates. 15 seconds
Stage #2-#4
Increase Time
The amount of time after the previous stage has enabled that the process temperature
must remain above the process setpoint before the precooling stage activates.
15 seconds (pads)
60 seconds (spray)
Stage #2-#4
Decrease Time
The amount of time that the process temperature must remain below the process setpoint
before the precooling stage deactivates. 15 seconds
Figure 33