T/H Offset Scaling; Auto Flush Cycle - Black Box CRCW-12 User Manual

4.5.5.6.3 T/H Offset Scaling

The Service>Options>T/H Offset Multiplier screen allows you to enter a multiplier to scale both the temperature and humidity cut-
in/cut-out offsets. The multipliers are factored to the system offset values set in the Service menu (Sections 4.5.5.1 and 4.5.5.2).
Temp. Cut-in Offset= 2.0°F;
Humidity Cut-in Offset= -5.0%;
EXAMPLE 1: Temperature Offset Multiplier
With the default cut-in offset for temperature at 2.0° F, a multiplier of 1.0 x 2° F = 2° F. This means the unit will begin operating
in the cooling mode at 74.0° F (Setpoint 72.0° F + Offset 2° F). Conversely, with the default cut-out offset at 0.3° F, the cooling
mode will turn off at 72.3° F.
EXAMPLE 2: Temperature Offset Multiplier
If 2.0 is entered, the offset for temperature is multiplied by 2.0. (2.0 x 2° F= 4° F). This means the unit will begin operating in the
cooling mode at 76.0° F (Setpoint 72.0° F + Offset 4° F).
Conversely, the cooling mode will turn off at 72.6° F.
(Setpoint 72.0°F + [2.0 x Cut-out Offset 0.3°F]).
72.0° F + 0.6° F = 72.6° F
EXAMPLE 3: Humidity Offset Multiplier
With the default cut-in offset for humidity at -5%, if a multiplier of 0.7 is entered, M.0.7 x -5% = -3.5%. This means the
humidifier will begin operating at 41.5% RH (Setpoint 45.0% + Offset -3.5%). Conversely, with the default cut-out offset at -2%
the humidification mode will turn off at 43.6% RH.

4.5.5.6.4 Auto Flush Cycle

The Service>Options/Flush Cycle screen may be used to enable a periodic flushing of the CW coils with the control valve open at
100%. This is used to remove any sediment that may have collected.
If enabled, you may set a minimum valve opening threshold below which a periodic flush cycle is required. That is, if the control
valve position ever exceeds the percentage entered since the last flush cycle, the scheduled flush cycle will be skipped and a new
interval will begin. If the valve does not reach the minimum open position entered, a flush cycle will occur when the interval since
the last flush cycle expires. The interval between flushes may vary from 1 hour to 720 hours (30 days). The duration of the flush
cycle may be varied from 30 to 300 seconds. The number of flushes displayed at the bottom of the screen is the total number of
flush cycles since the A/C unit was initialized.
Figure 4-58. T/H Offset Scaling screen.
Default Cut-in/Cut-out Offsets
Cut-out Offset= 0.3°F
Cut-out Offset= -2.0%
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Chapter 4: E2 Controller
Page 71