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applications, this is an improvement over using an external
humidistat, which only supplies humidity when auxiliary heat
is on.
2. Fan Humidify Mode—This configuration allows a humidity
demand to turn on the fan and the humidifier together, even if
there is no heat demand. It is particularly useful when a
furnace is oversized, resulting in short heating cycles. It allows
the humidifier to run longer, supplying more humidity to the
home. Note that fan hours will increase, using more electric-
ity. Also, the humidifier delivers less moisture to cooler air
than it does to heated air.
3. Auto Humidify—This feature is designed to eliminate the
problem of sweating windows in very cold weather. When
selected, the set point is reduced by 1 percent for every drop
of 2°F. in outdoor temperatures between 50°F. and 0°F. The
set point may be changed at any time. It will continue to track
outdoor temperature from the new set point and the current
outdoor temperature. The adjusted set point range is still
limited between 10% and 45% relative humidity. To use this
feature, the outdoor temperature sensor MUST be attached. If
not, an E3 error message will be displayed.
4. Auto and Fan Humidify—The two choices of Auto Humidify
nd Fan Humidify are combined in this selection.
5. Humidify Off—The humidify function can be turned off
completely. This does not require changing existing set points.
To exit humidity setup mode, press END button, or if no buttons
are pressed for 3 minutes, the User Interface will save and exit this
mode, returning to normal operation.
Table 1—Displays of Available Humidify Modes
SELECTION
MODE DISPLAY FAN DISPLAY HUMIDIFY DISPLAY
Normal Humidity
Blank
Fan Humidity
Blank
Auto Humidity
Auto
Auto and Fan
Auto
Humidify Off
Blank
HSP = Humidity Set Point
OF = Off
Dehumidification Description
Comfort Zone II -B contains a rich set of capabilities for the
enhancement and control of dehumidification, particularly when
used with a variable speed (ICM) blower. Depending on the type
of equipment used, compressor speed, blower speed, set point
adjustment, and equipment cycling are modified to provide added
dehumidification.
A dehumidification set point(separate from the humidification set
point) can be set to a value between 50 percent and 90 percent
humidity or can be turned off. When the humidity rises above this
set point by 2 percent, the dehumidify output is turned off. When
the humidity falls to 2 percent below this set point, the dehumidify
output turns on, supplying 24vac at its output. This output can be
used to control any 24-vac device which decreases humidity when
its control signal is removed.
When a variable speed blower with a dehumidify input is used
with the system, the dehumidify output can be connected to its
dehumidify input. This connection provides reduced cooling air
flow while dehumidification is needed yielding better moisture
removal from cooling air.
If the system has a 2-speed compressor (as selected by Equipment
Controller DIP switch No. 2) and a PSC blower (as selected by
User Interface Option No. 5), a dehumidify demand will make
Blank
HSP Value
Fan
HSP Value
Blank
HSP Value
Fan
HSP Value
Blank
OF
compressor operate at high speed only for any cooling demand.
High speed provides better water removal than low speed when a
2-speed compressor is used with PSC blower.
Another selection provides humidity control by operating the
cooling system when cooling is not required. If the humidity rises
above the dehumidification set point, a special dehumidification
routine is executed. As long as zone temperatures are not more
than 3°F below their cooling set points, a dehumidify demand will
turn on the cooling equipment but will limit its ON time to no more
than 10 minutes at a time.
Finally, OUT zones are used to their maximum capability. When
a zone is set to OUT it can be used to help remove humidity by
cooling it as much as possible. When there is a dehumidify demand
and a zone set to OUT, its damper is fully opened, and it can be
cooled down to as low as 70°F. If it reaches 70°F its damper will
close.
When all zones are set to OUT the house is in vacation mode. The
cooling equipment will come on either to maintain the house
below 85°F or to maintain the dehumidify set point by cooling the
house down to as low as 70°F. This is a valuable feature for
unoccupied homes in hot and damp climates.
Dehumidification Setup
IMPORTANT: It may be advisable to configure the dehumidify
control as part of the system installation process. Following is a
brief description of the dehumidify setup process. It is also covered
more thoroughly in the Owner's Manual.
There are 4 selections for dehumidification in the cooling mode:
1. Normal Dehumidify
2. Cool to Dehumidify
3. Vacation Dehumidify
4. OFF
To make a dehumidification selection or change the dehumidify
(dh) set point, a 2-button keypad press is required. Press SET
TIME/TEMP and FAN buttons simultaneously (indicated on
keypad by the RH symbol) to enter humidity mode. Either hu
(humidify) or dh (dehumidify) will appear on the clock display.
Use the SET TIME/TEMP button to select dh (dehumidify). The
actual humidity now appears in the large display, the dehumidify
set point appears in the cool set point display, and the small
triangle icon below the set point is turned on when the dehumidify
output is active. The UP and DOWN buttons now adjust the
dehumidify set point. The MODE button scrolls through the
available dehumidification modes. These are described below.
Table 2 shows the display indication for each of the dehumidifi-
cation modes below. Note special instructions for the Vacation
Dehumidify mode.
1. Dehumidify Off—This is used to disable dehumidification. It
is indicated on the display by OF in the dehumidify set point
location.
2. Normal Dehumidify Mode—this is the factory default. When
normal dehumidify is selected, the compressor will not turn on
without a cooling demand. If a dehumidify demand exists
while cooling, the dehumidify output will be active (24vac
removed from DHUM terminal of Equipment Controller). A
variable speed blower will respond by reducing its airflow by
20%. If the fan is set for continuous operation (fan mode =
ON) the fan will turn off for 5 minutes at the end of each
cooling cycle to allow condensate draining and prevent
re-evaporation. For this to work properly, the blower off delay
of the equipment itself must be defeated. In this mode, the
dehumidify set point appears and can be set to any value
between 50 and 90% relative humidity.
14
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