501054-UIM-A-0909
Johnson Controls Unitary Products
7
DEHUMIDIFICATION CONTROL
A dehumidification control accessory 2HU06700124 may be used with
variable speed air handlers or furnaces in high humidity areas. This
control works with the variable speed indoor unit to provide cooling at a
reduced air flow, lowering evaporator temperature and increasing latent
capacity. The humidistat in this control opens the humidistat contacts on
humidity rise. To install, refer to instructions packaged with the acces-
sory and Figures 10 - 15. Prior to the installation of the dehumidification
control, the jumper across the HUMIDISTAT terminals on the indoor
variable speed air handler or furnace CFM selection board must be
removed.
During cooling, if the relative humidity in the space is higher than the
desired set point of the dehumidification control, the variable speed
blower motor will operate at lower speed until the dehumidification con-
trol is satisfied. A 40-60% relative humidity level is recommended to
achieve optimum comfort.
If a dehumidification control is installed, it is recommended that a mini-
mum air flow of 325 cfm/ton be supplied at all times.
CFM SELECTION BOARD SETTINGS
For proper system operation the CFM Selection Board jumpers must be
set properly.
Refer to the Tabular Data Sheet for the recommended air flow settings
for each size condensing unit.
Set the cooling speed per the instructions for the air handler or furnace
by selecting the correct COOL and ADJ taps. Verify the airflow using
the LED display on the CFM selection board.
The HUMIDISTAT jumper must also be removed if a dehumidistat is
installed.
If installed as a communicating system (outdoor, indoor and thermo-
stat), the system will automatically adjust to the optimal airflow settings.
These parameters can also be modified using the communicating ther-
mostat. Refer to the communicating thermostat owner’s manual for this
procedure. Manual setting of the airflow jumpers on the ID equipment
is not necessary with the communicating thermostat.
FIGURE 7:
CFM Selection Board
HEA
T
DELA
Y
COOL
ADJUST
A
B
C
D
A
B
C
D
LED
2
FIGURE 8:
Communicating HP with Communicating Air Handler or
Furnace
FIGURE 9:
Communicating HP with Non-Communicating Air Handler
or Furnace using Communicating Interface Control
R
C
Y1
Y2
Touch Control
Communicating
Control
Air Handler/Furnace
Communicating
Control
Heat Pump
Communicating
Control
GND
or C
GND
or C
B-
R
A+
GND
or C
GND
or C
B-
R
A+
GND
or C
GND
or C
B-
R
A+
R
C
Y1
Y2
HUM
W2
DHUM
W
G
C
R
O
Y
Y2
HUM
W2
DHUM
W
G
C
R
O
Y
Y2
Touch Control
Communicating
Control
Communicating
Indoor
Interface Control
Non-Communicating
Indoor Unit
Heat Pump
Communicating
Control
Wire per
non-comm.
installation
manual
Assume that
connections
are from
thermostat
GND
or C
GND
or C
B-
R
A+
GND
or C
GND
or C
B-
R
A+
GND
or C
GND
or C
B-
R
A+