®
035-14511-000 REV B (1299)
12
Unitary Products Group
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 premium Stealth
condensing unit with a TS
compres-
sor 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
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 sys-
tems opens the humidistat contacts on humidity rise.
They
are wired to the control system per figure 7.
A dehumidistat installed with a single speed or 2-speed air han-
dler 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 airflow to
limit the number of time the unit will run second stage only for
dehumidification purposes. The dehumidistats for these sys-
tems close the dehumidistat contacts on humidity rise. They
are wired to the control system per figures 8 through 10.
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 thermo-
stat 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-
TABLE 1: R-22 SATURATION TEMPERATURE
ST
1
P
2
90
168
91
171
92
174
93
176
94
179
ST
P
95
182
96
185
97
187
98
190
99
193
ST
P
100
196
101
199
102
202
103
205
104
208
ST
P
105
211
106
214
107
217
108
220
109
223
ST
P
110
226
111
229
112
233
113
236
114
239
ST
P
115
243
116
246
117
250
118
253
119
256
ST
P
120
260
121
263
122
267
123
271
124
274
ST
P
125
278
126
282
127
285
128
289
129
293
ST
P
130
297
131
301
132
305
133
309
134
313
1.
ST = Saturated Temperature
2.
P = Pressure
