PAGE 6
Pub. No. 11-BC08D1-7
INSTALLER'S GUIDE
American Standard has always recommended installing approved
matched indoor and outdoor systems.
All American Standard split systems are AHRI rated with only
TXV indoor systems.
The benefits of installing approved indoor and outdoor split
systems are maximum efficiency, optimum performance and the
best overall system reliability.
The following charging methods are therefore prescribed for
systems with indoor TXV’s.
1. Subcooling (in the cooling mode) is the only recommended
method of charging above 55°F outdoor ambient temperatures.
2. For best results - the indoor temperature should be kept
between 70°F to 80°F. Add system heat if needed.
3. At startup, or whenever charge is removed or added, the
system must be operated for a minimum 20 minutes to stabilize
before accurate measurements can be made.
4. Measure Liquid Line Temperature and Refrigerant Pressure
at service valve.
5. Determine total refrigerant line length, and height (lift) if
indoor section is above the condenser.
6. Determine the Design Subcool Charging Temperature from
the unit nameplate.
7. Locate this value in the appropriate column of the Subcool-
ing Charging Table. Locate your liquid line temperature in the
left column of the table, and the intersecting liquid line pressure
under your nameplate subcool value column. Add refrigerant to
raise the pressure to match the table, or remove refrigerant to
lower the pressure. Again, wait for 20 minutes for the system
conditions to stabilize before adjusting charge again.
8. When system is correctly charged, you can refer to System
Pressure Curves (in Service Facts) to verify typical perfor-
mance.
SUbcooLING cHARGING IN cooLING AbovE 55°f oD AMbIENT
R-410A SUbcooLING cHARGING TAbLE
LIQUID
TEMP. (°F)
DESIGN SUBCOOLING VALUES (°F)
8
10
12
14
LIQUID LINE PRESSURE (psi)
55
179
185
191
198
60
195
201
208
215
65
211
218
225
232
70
229
236
243
251
75
247
255
263
271
80
267
275
283
291
85
287
296
304
313
90
309
318
327
336
95
331
341
351
360
100
355
365
376
386
105
381
391
402
413
110
407
418
429
441
115
435
446
458
470
120
464
476
488
501
125
495
507
520
533
From Dwg. D154557P01 Rev. 1
1. The Subcool Charging Method in cooling is not recommended
below 55°F outdoor ambient.
2. The only recommended method of charging at outdoor am-
bients below 55°F, is to weigh in the charge in the heating
mode.
3. Use Nameplate charge plus standard charge adders for line
length.
SUbcooLING cHARGING bELow 55°f oD AMbIENT - IN HEATING oNLy
SUBCOOL CHARGING TABLE CORRECTIONS FOR LINE LENGTH AND RISE
60
50
40
30
25
Add 10 psig to Subcool Charging Table Pressure
20
15
Use Design Subcool Value from Table
10
0
Subtract 10 psig from S.C. Table Pressure
10
20
25
30
40
60
80
TOTAL REFRIGERANT LINE LENGTH (FEET)
REFRIGERANT
LINE LIFT (FEET)
4. Check liquid line temperature and pressure (at the OD
valves) to obtain a minimum of 10°F subcooling.
5. Add charge if a minimum of 10°F subcooling is not obtained
with the nameplate charge plus line length correction.
6. It is important to return in the spring or summer to accurately
charge the system in the cooling mode at outdoor ambients
above 55°F.
