262673-UIM-B-0707
Unitary Products Group
5
SECTION IV: LOW VOLTAGE CONTROL
CONNECTIONS
The 24 volt power supply is provided by an internally wired low voltage
transformer which is standard on all models. See the unit wiring label.
Field supplied low voltage wiring can exit the unit on the top right hand
corner or the right hand side panel. Refer to Figure 3.
Remove desired knockout and pierce foil faced insulation to allow wir-
ing to pass through. Use as small of a hole as possible to minimize air
leakage.
Install a 7/8” plastic bushing in the selected hole and keep low voltage
wiring as short as possible inside the control box.
To further minimize air leakage, seal the wiring entry point at the outside
of the unit.
The field wiring is to be connected at the screw terminals of the control
board. Refer to Figure 8.
NOTE:
All wiring must comply with local and national electrical code
requirements. Read and heed all unit caution labels.
The low voltage connections may be connected to the screw terminals
or the quick connect terminals. The screw terminals and the quick con-
nect terminals are physically connected on the control board.
HUMIDITY SWITCH INPUT
The air handler control is designed to work with a humidity control that
closes when the humidity is below the set-point. The control is open
when the humidity is above the set-point. This humidity control may be
referred to as a humidistat or a dehumidistat.
The humidity switch controls both humidification and de-humidification
operation of the control. The control provides humidification using the
HUM OUT relay output and de-humidification by lowering the blower
speed. This is accomplished using the LOW FAN output and a field
installed two-speed fan relay kit for non-variable speed models and the
de-humidification input of the motor for variable speed models. The
humidity switch should be connected to the R and HUM terminals of the
control. See Figure 8.
SECTION V: REQUIRED CONTROL
SET-UP
IMPORTANT:
The following steps must be taken at the time of installa-
tion to insure proper system operation.
1.
Consult system wiring diagram to determine proper thermostat
wiring for your system.
2.
HEAT ENABLE jumper must be set to NO HEAT position.
3.
If a humidstat is installed, change HUM STAT jumper from NO to
YES.
4.
Set the MODE jumper to A/C (Air Conditioner) or HP (Heat Pump)
position depending on the outdoor unit included with the system.
FUNCTIONALITY AND OPERATION
Jumper Positions
Refer to Figure 5 for details of control board showing component loca-
tions.
Heat Enable Jumper
The jumper must be in the NO HEAT position. This unit cannot be used
with heat.
With the jumper in the NO HEAT position, the control will not energize
the heat relay outputs or sense the limit switch input.
If the jumper is not present, the control will operate as if the jumper is in
the HEAT position. If the jumper is not present and a heat kit is not
present, the control will sense an open limit condition and the blower
will run continuously.
FIGURE 5:
Control Board
HEAT ENABLE
JUMPER
HUM OUT
RELAY OUTPUT
EAC
RELAY OUTPUT
LOW FAN
RELAY OUTPUT
SPARE JUMPER
HUM STAT JUMPER
MODE JUMPER
FUSE
TABLE 2:
Low Voltage Connections
Terminal
Signal
Comment
R
24 VAC power (fused)
G
Continuous Fan operation
Y/Y2
Second or full stage
compressor operation
Y1
First stage compressor
operation
Not used with outdoor units
having one stage compressors.
W2
Second stage heat operation
W1
First stage heat operation
O
Reversing valve operation
24 VAC will be present at this
terminal when the MODE
jumper is in the AC position.
This is normal.
HUM
Humidity switch input
24 VAC will be present at this
terminal when the HUM STAT
jumper is in the NO position.
This is normal.
X/L
Connection point for
heat pump fault indicator
This terminal is a connection
point only and does not affect
air handler control operation.
COM
24 VAC common
