Instruction manual

12
DEHUMIDIFICATION — Dehumidification is done only dur-
ing cooling. Depending on type of equipment used, compressor
speed, fan speed, set point adjustment, and equipment cycling
are modified to provide added dehumidification. A dehumidifi-
cation set point (separate from humidification set point) is avail-
able to the user. It can range from 46% to 98% relative humidity.
When actual humidity is higher than the set point, a
dehumidification demand exists. The thermostat responds by
activating the dry contacts (D1/D2 when enabled in Option 19).
The thermostat may also control the compressor and fan,
depending on equipment type and dehumidification selection
choice. The 3 available selections are described below. A
mandatory 30-second fan off delay will be enforced if there has
been a call for dehumidification during a cooling call. The
amount of extra dehumidification available is very dependent on
the type of equipment. Without a variable-speed fan, the
system’s ability to adjust dehumidification is very limited.
Normal Dehumidification Operation
— When normal dehu-
midification is selected, the compressor will not turn on without
a cooling demand. If dehumidification demand exists while
cooling, dry contact will also be active. This output commands
variable-speed fans to reduce their airflow, which improves wa-
ter removal from the cooled air.
Cool to Dehumidification
— The cool to dehumidification se-
lection tells the system to operate the compressor, within limits,
when there is a dehumidification demand even if there is no
cooling demand. The limits are that the system may overcool up
to 3° F (1.7° C), but no more, while attempting to satisfy a dehu-
midification demand. Within this 3° F (1.7° C) range, there is an
additional balance between overcooling and humidity satisfac-
tion.
When overcooling must occur, the dehumidification set point
is adjusted upward by 2% per degree of overcooling. For exam-
ple, a cooling set point of 76 F (24.4 C) and a dehumidification
set point of 60% is equivalent to a cooling set point of 75 F
(23.9 C) and a dehumidification set point of 62%. This dehumid-
ification set point change is internal to the thermostat and is not
shown on the display.
Dehumidification Off
— Dehumidification can be turned off
completely. This can be done without changing existing set
points.
To Select Dehumidification
— Press the soft key below the de-
humidification icon button to bring up dehumidification selec-
tions. Dehumidification options are only available when in Cool-
ing mode. When system is in AUTO mode, dehumidification
options are available if the last system operation was a call for
cooling.
If FAN is set for continuous operation (Fan On icon dis-
played), then the G output is turned off for 30 seconds at the end
of each cooling cycle as long as dehumidification demand exists.
Like humidification, dehumidification actions are initiated when
humidity is 1% above set point and are terminated when humidi-
ty drops to 4% below set point. This prevents unnecessary tog-
gling of dehumidification actions when humidity is near the set
point.
Holiday — A holiday selection is available specifically for
times when the space will not be occupied for an extended peri-
od. Holiday mode has an automatic hold, meaning that set points
are not affected by the programmed schedule. Holiday mode is
active for a specified period of time. While in Holiday mode, the
system provides temperature and humidity protection for the
space in the selected mode, but not comfort. When Holiday
mode is active, an arrow will be displayed beside “HOLIDAY”
in the upper left corner of the display. Please refer to the Owner’s
Manual for details about configuring the Holiday Schedule.
HOLIDAY SET POINTS — A special set of temperature and
humidity set points are active in Holiday mode. They are adjust-
able by the user and are used exclusively for Holiday mode.
They are remembered from one holiday selection to the next.
See Table 4 for default holiday values.
Table 4 — Holiday Default Values
HOLIDAY HUMIDIFICATION — Normal humidification is
available using holiday set points. Auto humidification is avail-
able, adjusting its set point with outdoor temperature the same as
when occupied. Holiday humidification can be turned off inde-
pendently of occupied humidification. While setting the Holiday
set points, the Holiday humidification set point is accessible by
pressing the soft key below the humidification icon when the
box is around the heating set point.
HOLIDAY DEHUMIDIFICATION — Normal Dehumidifica-
tion, Cool to Dehumidification, and Dehumidification OFF are
all available in Holiday mode. The selection of one of these can
be different from that of occupied mode. Holiday dehumidifica-
tion selection and set points are remembered the next time holi-
day is used. While setting holiday set points, the holiday dehu-
midification set point is accessible by pressing the soft key be-
low the dehumidification icon when the box is around the
cooling set point.
OPERATION
Unoccupied Override —
The OCCUPIED button is
only active:
• during the unoccupied periods
• when hold is active
• when holiday is active
The OCCUPIED button is inactive during occupied periods
(OCC, OCC2, and OCC3).
When the user presses the OCCUPIED button, the set points
change to the occupied settings and temporary hold timer is set
for two hours. The user can adjust the temporary hold timer to
any value in 15-minute increments from15 minutes to the maxi-
mum number of hours specified by the installer in configuration
Option 38.
When the temporary hold timer counts down to zero, the set
points will change to the program schedule settings for that time
of day. If smart recovery conditions are satisfied, the set points
will change from the occupied values to the program schedule
values.
If hold is active, the temporary hold timer is not displayed.
The fan will run according to the setting specified by the installer
in configuration Option 36.
OUTSIDE TEMPERATURE
-20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 F
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
TARGET HUMIDITY
9
8
7
6
5
4
3
21
(-28.9) (-26.1) (-23.3) (-20.5) (-17.8) (-15.0) (-12.2) (-9.4) (-6.7) (-3.9) (-1.1) (1.7) (4.4) (7.2) (10) C
a33-9301
Fig. 14 — Auto Humidification
MODE AUTO SET POINTS
Fan Follows setting of Option 37
Heat Set Point 55 F (12.8 C)
Cool Set Point 85 F (29.4 C)
Humidification Set Point 20%
Dehumidification Set Point 98%