035-16408-001 Rev. B (101)
Unitary Products Group
11
RECORDING TOTAL SYSTEM CHARGE
The factory charge in the outdoor unit is listed on tabular data
sheet and includes enough charge for the unit, matched
evaporator and 15 feet of lines. Installations over 15 feet long
and some indoor coil matches may require some additional
charge.
The “TOTAL SYSTEM CHARGE” must be permanently
stamped on the unit data plate.
Refer to the tabular data sheet and determine the system
charges as follows:
1.
Determine the condensing unit charge.
2.
Determine indoor coil adjustment charge.
3.
Calculate the additional charge for line lengths greater
than 15 feet using refrigerant line adder (oz./ft.).
4.
Total system charge = Item 1 + Item 2 + Item 3.
5.
Permanently stamp the unit data plate with the total
amount of refrigerant in the system.
SYSTEM FUNCTIONS
This
condensing unit with a TS
ä
compressor is designed to
provide maximum efficiency and comfort to the user. This unit
has a control with many unique features that are described
below.
FIRST AND SECOND STAGE COMPRESSOR
MODES
The TS
ä
compressor is a single two cylinder-reciprocating
compressor. The first stage mode operates only one cylinder
producing a part load capacity and high operating efficien-
cies. The system is sized so that over 80% of the cooling
requirements are met by this mode. The operating time for
first stage will be slightly longer than with a single speed com-
pressor system. The high efficient operation offsets the
longer run time for a total energy reduction. The second
stage mode operates both cylinders for full capacity to meet
peak cooling demands.
To operate one cylinder, the compressor motor runs in the
reverse direction of the two cylinder (full capacity) mode. This
is accomplished by reversing the motor run and start wind-
ings through the control circuitry.
All units come factory equipped with Hard Start components
sized and optimized for one and two cylinder operation. Since
all installations must be with a TXV valve and the switching
time from first to second stage is 5 seconds, hard start com-
ponents are mandatory. The Hard Start components are
wired across the compressor run capacitor and not the com-
pressor start windings.
DEHUMIDIFICATION
The product is designed to run longer on first stage than a
regular single speed compressor system. This additional run
time provides for better dehumidification and consistent room
temperatures. However, there may be installation environ-
ments that the humidity levels are unacceptable. In this case
the addition of a humidity control will resolve these issues.
A humidistat installed with a variable speed air handler or fur-
nace reduces the airflow of the blower by 15% of the pro-
grammed speed during the dehumidification mode. This
lower airflow reduces the evaporator temperature increasing
the latent capacity. The humidistat for these variable speed
systems opens the humidistat contacts on humidity rise. They
are wired to the control system per figure 4.
A dehumidistat installed with a single speed or 2-speed air
handler or furnace will force the system into second stage
mode to increase the latent capacity. It is critical that the low
speed blower operation is set as low to the recommended air-
flow to limit the number of times the unit will run second stage
only for dehumidification purposes. The dehumidistats for
these systems close the dehumidistat contacts on humidity
rise. They are wired to the control system per Figures 5
through 7.
COOLING OPERATION
The condensing unit requires a two stage cooling indoor
room thermostat to operate correctly. The outdoor unit control
has a fault signal output (X/L) that can light a fault light on a
thermostat if that feature is available with the thermostat
used.
With a call for first stage cooling (Y1), the outdoor fan and the
first stage of the compressor are energized following the
completion of a five-minute anti-short cycle timer. Simulta-
neously, the indoor blower is energized (see indoor blower
operation section).
With a call for second stage cooling (Y2), while the unit is
operating in the first stage mode, the contactor opens de-
energizing the outdoor fan and the compressor. The control
will switch the control circuit and five seconds later will ener-
gize the contactor starting the outdoor fan and the compres-
sor in the second stage mode. Additionally, the control
outputs a 24v signal (at Y2 OUT) to control the indoor blower
at the correct CFM.
If there is a call for second stage cooling (Y2) prior to the unit
operating the first stage (i.e. if call occurs during the five
minute anti-short cycle period), then the control will switch the
control circuit and will energize the contactor starting the out-
door fan and the compressor in the second stage mode.
Additionally, the control outputs a 24v signal (at Y2 OUT) to
control the indoor blower at the correct CFM.
When the second stage of the room thermostat is satisfied
only, the unit will continue to operate in the second stage
mode.
When the first stage of the room thermostat is satisfied, the
control will de-energize the contactor stopping the outdoor
fan and the compressor.
If the room thermostat calls for second stage cooling (Y2) on
two consecutive cooling cycles, the next call for cooling for
either first (Y1) or second (Y2) stage will energize the unit in
the second stage mode. The above mode will be reset to per-
mit start up on first stage with only a Y1 call when the second
stage operational cycle runs less than 15 minutes. This mode
can also be reset when servicing the equipment by removing
24 V to the control.
