9
Table 2. Demand Defrost Curve Profiles
JUMPER
POSITION
MINIMUM TIME
BETWEEN
DEFROSTS
(MINUTES)
TERMINATE
TEMPERATURE
(° F)
COMPRESSOR
DELAY
FUNCTION
1
20
40
NO
2
20
40
YES
3
20
75
NO
4
20
75
YES
Star Bushing
Bolt
Nut
Ambient Sensor
Plastic Clip
Nut
Figure 6. Ambient Sensor Mounting
3. Route the ambient sensor through the 7/8” hole in the
corner panel of the unit, and then through the 7/8” hole
in the mounting bracket.
4. Route the sensor through the star bushing. Use the star
bushing to secure the mounting bracket to the unit.
5. Secure the ambient sensor inside the plastic clip and
secure it to the mounting bracket with the screw and
nut provided.
6. Install one spacer next between the plastic clip and
mounting bracket.
7. Bend the mounting bracket into position. Install the
mounting bracket to the unit using the screw in the
corner panel.
4 minutes, unless the coil temperature is above the
selected terminate temperature.
• The system can be manually forced into defrost mode at
any time by shorting the
TEST
terminals on the demand
defrost board together for more than 9 seconds. The
coil temperature sensor does not need to be cold when
the unit is forced into defrost. After the
TEST
input is
shorted, the defrost mode will terminate in 13.7 minutes,
if the coil temperature is above the terminate set-point,
or when the
Y
input is removed, whichever occurs first.
NOTE:
If a demand curve is selected which has a 30
second compressor time delay, the delay is reduced to
10 seconds in TEST mode.
Demand Defrost Control
The demand defrost board controls the defrost cycle
in response to ambient temperature, outdoor coil
temperature and accumulated compressor run time. The
heat pump is allowed to operate in the heating mode
until the combination of outdoor ambient and outdoor
coil temperatures indicate that defrosting is necessary,
based on the programmed defrost curve. There are four
preprogrammed defrost curves on the board.
• A jumper pin is used to switch between the different
curves. The default jumper position is curve 1 and is the
recommended setting for most standard applications.
for additional defrost curves settings.
• The factory default setting does not include a 30 second
compressor delay function and has a 40 ° F defrost
terminate temperature. If additional defrost time is
needed, a higher terminate temperature is available
by selecting a different demand curve.
NOTE:
The 30
second compressor delay occurs when the unit enters
defrost and exits defrost. The delay function is optional
and based on the demand curve selected.
• The standard defrost cycle will terminate after 13 minutes
and 39 seconds or when the coil temperature reaches
its terminate temperature, whichever occurs first.
• The defrost board is equipped with a 5 minute Anti-Short
Cycle Timer (ASCT). The compressor will not turn on
until it reaches the minimum 5 minute off time.
• The control contains a forced - defrost feature, which
places the system into defrost mode every 6 hours and
Thermostat Connections
• This heat pump requires a 2-stage Cooling and 3 stage
heating thermostat if electric heat is field installed. The
heat-cool thermostat prevents simultaneous operation
of the heating and cooling units and is equipped with
an ON-AUTO fan mode that allows the home owner to
operate the indoor blower when only air circulation is
desired.
• The control circuit wiring must comply with the current
provisions of the NEC (ANSI/NFPA 70) and with
applicable local codes having jurisdiction. Thermostat
connections should be made in accordance with the
instructions supplied with the thermostat and the indoor
equipment.
• The low voltage wires must be properly connected to
the units low voltage terminal block.
1. Route 24V control wires through the sealing grommet
) near the power entrance.
2. Connect the control wires to the defrost board and
blower relay wire (
• Several thermostat options are available depending
on the accessories installed with the unit. Select a
thermostat that operates in conjunction with the installed
accessories.
• The thermostat should be mounted about 5 feet above
the floor on an inside wall. DO NOT install the thermostat
on an outside wall or any other location where its
operation may be adversely affected by radiant heat from
fireplaces, sunlight, or lighting fixtures, and convective
heat from warm air registers or electrical appliances.
Refer to the thermostat manufacturer’s instruction sheet
for detailed mounting information.
