8
See the unit wiring label for proper high and low
voltage wiring. Make all electrical connections
in accordance with all applicable codes and
ordinances.
Use a separate branch electrical circuit for this
unit. A means of electrical disconnect must be
located within sight of and readily accessibility
to the unit. Internally mounted circuit breakers
are available as fi eld installed options. These
circuit breakers can be used as an electrical
disconnect.
The unit is shipped from the factory wired for 240
volt transformer operation. For 208 volt operation,
remove the lead from the transformer terminal
marked 240V and connect it to the terminal
marked 208V. For maximum ampacity and over
current protection, see the unit rating plate.
Provide power supply (or supplies) for the unit in
accordance with the unit wiring diagram, and the
unit rating plate. Connect the line-voltage leads
to the corresponding terminals on the contactor
(or the circuit breaker when the fi eld installed
circuit breaker kits are used) inside the control
compartment. Use only copper wire for the line
voltage power supply to this unit. Use proper code
agency listed conduit and a conduit connector
for connecting the supply wires to the unit and
for obtaining proper grounding. Grounding may
also be accomplished by using the grounding
lug provided in the control box.
WARNING:
The unit cabinet must have and
uninterrupted or unbroken electrical
ground to minimize personal injury if
an electrical fault should occur. This
ground may consist of electrical wire
or approved conduit when installed in
accordance with existing national or
local codes.
Selecting Proper Airfl ow for Variable Speed
Units —
Variable speed packaged heat pump units
are equipped with a microprocessor-controlled
variable speed motor that is pre-programmed to
deliver optimum airfl ow in a variety of conditions
and system confi gurations. The packaged heat
pump units respond directly to the thermostat
inputs, as well as the optional humidistat (Page
11) (If installed) and bonnet switch (Page 11) (if
installed). During normal operation, the motor will
gradually change speeds during start-up, shut
down, when thermostat inputs change, and when
the duct static pressure changes (vents closed or
opened, fi lter clogging, etc.). The packaged heat
pump unit is confi gured by setting the selector
switches and removing jumper connectors as
directed below.
IMPORTANT! This packaged
heat pump unit has been designed to give
the installer maximum fl exibility to optimize
system performance, effi ciency, and comfort.
Because there are so many different ways
to set up the packaged heat pump unit it is
important to read and follow these directions
carefully.
Selecting the Basic Cooling/Heat Pump
Airfl ow
—
The basic cooling/heat-pump airfl ow
is selected by setting switches 1 through 4
on the thermostat input board located on the
blower. All airfl ows for other modes of operation
(except electric heat) are determined by this
basic setting.
Table 1 shows the basic airfl ow values versus the
airfl ow selector switch settings. Table 1 also shows
the range of basic air fl ow settings recommended
for each nominal system capacity.
NOTE:
The CFM values listed in the tables are
not dependent on duct static pressure. The motor
automatically compensates for changes in duct
static pressure (within the limits of the motor).
For maximum capacity and energy effi ciency,
select an airfl ow at or near the top of the
range for that nominal capacity. For maximum
dehumidifi cation, select an airfl ow near the
middle or bottom of the range for that nominal
capacity. Additional information on humidity
control can be found in the sections labeled
“Humidistat” and “Delay Setting”.
NOTE:
If coil icing is observed, the basic cooling/
heat-pump airfl ow selected may be too low.
Double-check to be sure the setting selected is
within the range shown in Table 1. Also check
to be sure the system is properly charged (see
charging charts). If icing continues to occur, raise
the selected airfl ow one or two steps.
When operating in the heat pump mode, a higher
basic airfl ow setting will increase the energy
effi ciency and capacity but will also decrease
the supply air temperature. The optional Bonnet
Control Switch may be added to increase the
supply air temperature in the heat-pump mode
when the supply air temperature is below a
comfortable level. For more details see the
section labeled “Bonnet Control Switch”.
