Nordyne Single Package Heat Pump R-410A - Manual (Page 9)

9
Figure 8. Power Entry
Low Voltage
High Voltage
Overcurrent Protection
Generally, the best fuse or breaker for any heat
pump is the smallest size that will permit the
equipment to run under normal usage and provide
maximum equipment protection. Properly sized
fuses and breakers also prevent nuisance trips
during unit startup. If a fuse blows or a breaker
trips, always determine the reason. Do not
arbitrarily install a larger fuse or breaker and
do not, in any case, exceed the maximum size
listed on the data label of the unit.
Locating the Thermostat
Locate the thermostat away from drafts and
slamming doors. The thermostat must not be
installed on an outside wall or any other location
where its operation may be adversely affected
by radiant heat from fi replaces, sunlight, or
lighting fi xtures, or convective heat sources such
as supply air registers or electrical appliances.
Mount on an inside wall approximately fi ve feet
from the fl oor.
This heat pump is a two stage Cooling and
Heating appliance that requires a 2-stage
Cooling/Heating thermostat. 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.
Connect the low voltage wires to the respective
terminals on the thermostat base (Figure 9). See
thermostat instruction sheet for more detailed
information.
2-Speed Outdoor Fan Motor
(Select Models)
If the unit utilizes a 2-speed condenser fan motor,
this motor will operate on low speed when in low
cooling/heating, and on high speed when in high
cooling/heating.
Low Pressure Switch
The low pressure switch is factory installed and
located in the suction line internal to the unit. The
switch is designed to protect the compressor if a
loss of charge occurs. Under normal conditions,
the switch is closed.
If the suction pressure falls below 5 psig, then
the switch will open and de-energize the unit. The
switch will close again once the suction pressure
increases above 20 psig. The low pressure
switch interrupts the thermostat inputs to the unit.
Note: When the switch opens and then closes,
there will be a 3 minute short cycling delay before
the unit can energize.
High Pressure Switch
The high pressure switch is factory installed
and located in the compressor discharge line
internal to the unit. The switch is designed to de-
energize the system when very high pressures
occur during abnormal conditions. Under normal
conditions, the switch is closed.
If the discharge pressure rises above 575 psig,
the switch will open and de-energize the unit.
The switch will close again once the discharge
pressure decreases to 460 psig. The high
pressure switch interrupts the thermostat inputs
to the unit. Note: When the switch opens and
then closes, there will be a 3 minute short cycling
delay before the unit can energize.
Defrost Cycle Control
The defrost cycle is controlled by an adaptive
demand defrost board which features:
• Adaptive Demand Defrost algorithm.
• 4 Field selectable defrost termination
temperatures.
• Field selectable delay feature.
• High pressure and low pressure switches.
• Sensing of second stage compressor
demand.
• Test/speed up capability.
• Anti short cycle timer (3 minutes) for
compressor protection.
• On board diagnostics with fl ashing LED
for quicker troubleshooting. See Table 3
(page 11).
The adaptive Demand Defrost controls the
defrost cycle in response to an adaptive demand
algorithm that uses coil temperature and ambient
temperature. It provides user selectable defrost
termination temperatures (50° F - 80° F coil
temperature).