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V− OPTIONAL HUMIDITY CONTROL (A20)
COVER
VERTICAL SLIDE CONTROL
(control setpoint)
SLIDE
(ON CIRCUIT BOARD)
TERMINAL BLOCK
HINGES
BASE SECTION
INDICATING LIGHTS
Efficiency
Plus
PARTS IDENTIFICATION
NOTE−TO REMOVE COVER, HOLD BASE SECTION
AND GENTLY PULL THE COVER OUT AT THE BOT-
TOM AND PIVOT IT UP AND AWAY FROM BASE.
FIGURE 11
CONTROL WIRE ENTRY
HUMIDITY SENSOR
A−CCB1
Optional Comfort Control Board (CCB1) A20 may be
installed adjacent to the indoor thermostat (figure 11). The
control monitors indoor humidity conditions and creates a
dehumidification demand in response to indoor humidity
just as the thermostat creates a cooling demand in
response to indoor temperature. The CCB1 works in
combination with the indoor thermostat to adjust
compressor speed and indoor blower speed. Although the
control provides a dehumidification demand, only the
thermostat can directly control compressor operation. The
CCB1 cannot call for a compressor cycle by itself.
Principles of Cooling with Drier Air
The humidity comfort range for humans is between 40%
and 60% relative humidity (RH). A vertical slide on the
control allows the humidity setpoint to be adjusted within
that comfort range. 50% RH is the recommended initial
setpoint until personal comfort level is established. The
personal comfort level will vary with humidity as with
temperature. For example, if air at 75
°
F and 50% RH is
changed to 60% RH, the air will feel" much warmer.
Likewise, if the air is reduced to 40% RH, it will feel" much
cooler.
Even when inactive, the body evaporates a large amount of
moisture away from the skin. This evaporation produces a
cooling effect (during wintertime this phenomenon is called
wind-chill"). Dry air is capable of absorbing more moisture
away from the skin thereby increasing the cooling effect.
When the CCB1 senses that the indoor humidity level is
above the control setpoint, the control places the
CBX32MV and outdoor unit in a dehumidification mode .
To produce drier air, the CBX32MV will slow down the
speed of the air crossing the indoor coil. Because the air is
moving much slower than normal, the indoor coil is allowed
more time to remove moisture from the air (a higher
percentage of the air passing over the coil is cooled to its
dew point removing more moisture). At the same time the
two-speed outdoor unit will switch to high-speed to produce
a colder indoor coil. The colder indoor coil and slower
moving air combine to produce drier supply air.
NOTE−The indoor blower speed is reduced in order to
slow the air speed across the indoor coil. The supply air
exiting the unit may not feel as forceful. This is normal.
Remember that when the unit is in dehumidification
mode, the comfort level is increased because the unit is
producing cooler, drier air.
The exact sequence of operation to produce cooler, drier air
is described in the following section.
Operation
The CCB1 operates only during cooling mode. During
normal cooling operation, when there is no indoor humidity
demand, the unit operates as a straight two-speed cooling
system. First stage thermostat demand energizes the
compressor and indoor blower on low speed. Increased
cooling demand energizes the compressor and indoor
blower on high speed.
The control is equipped with a row of orange LED lights on
its face which indicate the amount of relative humidity
demand present. When one or more LEDs are lit, the
control signals the CBX32MV to begin dehumidification
mode. Tables 10 and 11 shows system response to
thermostat and CCB1 demand.
Calibration Precautions
Extreme care should be taken to avoid exposing the CCB1
to fumes from household chemicals. The humidity sensing
element in the CCB1 is a precise component which can be
damaged or the calibration changed by household
chemicals and cleaning agents. Make sure all household
chemicals are stored in a different room in the building.
Also, use only mild diluted soapy water when cleaning the
CCB1 cover or the area surrounding the CCB1. The
sensing element cannot be field calibrated. The CCB1
contains no field repairable parts and must be replaced
when damaged in this manner.
Agents which can damage the CCB1 include alcohol,
benzene, chlorine and chlorine based solutions, acetone
(nail polish remover), bug sprays and other household
cleaners.
Calibration can also be adversely affected by the
placement of the CCB1 with respect to the indoor
thermostat, exterior doors and windows and supply air
registers. Most thermostats have anticipation resistors
