Lennox 13ACX Installation And Service Procedure page 35

FOR COMPLETE CHARGING DETAILS, REFER TO THE OUTDOOR UNIT INSTALLATION INSTUCTION.
AIRFLOW CHECK - Both airflow and refrigerant charge must be monitored
for a proper system set‐up. It may be necessary to alternately check and
adjust the airflow and the refrigerant charge.
NOTE - Be sure that filters and indoor and outdoor coils are clean before testing.
To determine temperature drop across indoor coil (Delta-T), measure the entering air dry
bulb (DB) and wet bulb (WB) temperatures at the indoor coil. Find Delta-T in table 1. Measure
coil's leaving air DB and subtract that value from entering air DB. The measured difference
should be within +3ºF (+1.8ºC) of table value; if too low, decrease the indoor fan speed (refer
to indoor unit for information). If the Delta-T is too high, increase the indoor fan speed. Repeat
charging procedure and Delta-T (air flow adjustment) procedure until both are correct.
Example:
assume entering air DB - 72, WB - 64, leaving DB - 53. Therefore, Delta-T should
be 15 (per table); delta across coil is 72 - 53 or 19 (which is 4ºF higher than table value); action
necessary: increase fan speed.
Table 1. Evaporator Coil Delta-T
Dry bulb 80 24 24 24 23 23 22 22 22 20 19 18 17 16 15
temperature 78 23 23 23 22 22 21 21 20 19 18 17 16 15 14
of air 76 22 22 22 21 21 20 19 19 18 17 16 15 14 13
entering 74 21 21 21 20 19 19 18 17 16 16 15 14 13 12
indoor 72 20 20 19 18 17 17 16 15 15 14 13 12 11 10
coil (ºF) 70 19 19 18 18 17 17 16 15 15 14 13 12 11 10
ºF 57 58 59 60 61 62 63 64 65 66 67 68 69 70
[ Wet bulb temperature of air entering indoor coil
Table 2. Superheat (SH) Value
40 15 18 20 23 26 29 32 34 38 41 43 46 48 51
45 13 16 18 21 24 27 30 33 36 39 41 44 46 49
50 11 14 16 19 22 25 28 31 34 37 39 42 44 47
Dry bulb 55 9 12 14 17 20 23 27 30 33 36 38 40 42 44
temperature 66 7 10 12 15 18 21 24 27 30 33 35 38 40 43
of ambient 65 ‐ 6 10 13 16 19 21 24 27 30 33 36 38 41
air entering 70 ‐ ‐ 7 10 13 16 19 21 24 27 30 33 36 39
outdoor 75 ‐ ‐ ‐ 6
unit (ºF) 80 ‐ ‐ ‐ ‐
85 ‐ ‐ ‐ ‐
90 ‐ ‐ ‐ ‐
95 ‐ ‐ ‐ ‐
100 ‐ ‐ ‐ ‐
105 ‐ ‐ ‐ ‐
110 ‐ ‐ ‐ ‐
115 ‐ ‐ ‐ ‐
ºF 50 52 54 56 58 60 62 64 66 68 70 72 74 76
[ Wet bulb temperature of air entering indoor coil
11/07
*2P1107*
CHARGING INFORMATION
RFC System - +5ºF
9 12 15 18 21 24 28 31 34 37
5 8 12 15 18 21 25 28 31 35
‐ ‐ 8 11 15 19 22 26 30 33
‐ ‐ 5 9 13 16 20 24 27 31
‐ ‐ ‐ 6 10 14 18 22 25 29
‐ ‐ ‐ ‐ 8 12 16 21 24 28
‐ ‐ ‐ ‐ 5 9 13 17 22 26
‐ ‐ ‐ ‐ ‐ 6 11 15 20 25
‐ ‐ ‐ ‐ ‐ ‐ 8 14 18 24
Model -18
Table 3. Normal Operating Pressures
2
°F(°C) TXV System - Liquid Line (+10 psig) / Vapor Line (+5 psig)
65 (18) 233 / 132
70 (21) 251 / 133
75 (24) 265 / 133
80 (27) 292 / 135
85 (29) 314 / 136
90 (32) 338 / 137
95 (35) 362 / 138
100 (38) 388 / 140
105 (41) 415 / 141
110 (43) 444 / 142
115 (45) 475 / 143
2
°F(°C) Fixed Orifice (RFC) - Liquid Line (+10 psig) / Vapor Line (+5 psig)
65 (18) 233 / 121
70 (21) 250 / 124
75 (24) 270 / 128
]
80 (27) 291 / 131
85 (29) 313 / 134
90 (32) 335 / 136
95 (35) 359 / 138
100 (38) 383 / 140
105 (41) 409 / 142
110 (43) 436 / 145
115 (46) 464 / 147
Table 4. Approach (APP) Values
All 4 (2.2)
Table 5. Subcooling (SC) Values
All 10 (5.6)
1 Typical pressures; indoor evaporator match up, indoor air quantity, and evaporator load will cause
the pressures to vary.
2 Temperature of air entering outside coil.
3 Approach = Liquid Line Temp. minus Outdoor Ambient Temperature
4 Subcooling = Saturation Temp. minus Liquid Line Temp Temperature
]
-24 -30 -36
1
244 / 137 248 / 127 263 / 135 250 / 135
263 / 138 263 / 131 281 / 138 268 / 137
285 / 139 284 / 132 302 / 140 288 / 138
307 / 140 307 / 134 325 / 142 310 / 139
329 / 141 330 / 135 349 / 142 332 / 140
354 / 142 355 / 136 375 / 143 356 / 140
379 / 143 380 / 137 404 / 144 381 / 141
404 / 144 407 / 138 433 / 145 406 / 143
438 / 145 434 / 139 462 / 147 432 / 143
464 / 147 465 / 141 494 / 149 459 / 145
495 / 148 497 / 142 527 / 150 490 / 145
246 / 126 245 / 123 261 / 134 250 / 135
265 / 129 265 / 126 281 / 136 268 / 137
286 / 132 286 / 129 301 / 138 288 / 138
307 /135 308 / 132 324 / 140 310 / 139
330 / 137 331 / 135 346 / 142 332 / 140
353 / 140 355 / 138 371 / 144 356 / 140
378 / 142 380 / 140 396 / 146 381 / 141
402 / 143 405 / 142 422 / 148 406 / 143
428 / 145 431 / 144 448 / 150 432 / 143
456 / 147 458 / 146 477 / 151 459 / 145
486 / 149 487 / 148 506 / 153 490 / 145
3
-
TXV System - ºF (ºC) +1ºF (0.5ºC)
8 (4.4) 8 (4.4) 11 (6.1) 10 (5.6)
4
-
TXV System - ºF (ºC) +1ºF (0.5ºC)
10 (5.6) 9 (5.0) 12 (6.7) 8 (4.4)
401288S
*P401288S*
-42 -48 -60
240 / 130 242 / 130
257 / 131 266 / 131
278 / 132 286 / 132
299 / 133 309 / 133
323 / 134 332 / 134
344 / 135 357 / 135
369 / 136 381 / 136
394 / 137 407 / 137
418 / 139 433 / 138
446 / 140 459 / 140
477 / 141 488 / 141
248 / 127 255 / 126
266 / 130 274 / 128
284 / 132 294 / 131
305 / 134 317 / 134
325 / 137 339 / 136
347 / 139 362 / 138
371 / 141 386 / 140
394 / 143 413 / 142
418 / 144 435 / 144
445 / 146 462 / 146
472 / 147 490 / 148
6 (3.3) 9 (5.0)
10 (5.6) 7 (3.9)