Lennox Merit Series 14HPX Installation Instructions Manual page 20

Table 10. Normal Operating Pressures − Liquid +10 and Vapor +5 PSIG*
Use table 10 as a general guide when performing maintenance checks. This is not a procedure for charging the unit (Refer
to Charging / Checking Charge section). Minor variations in these pressures may be expected due to differences in instal-
lations. Significant differences could mean that the system is not properly charged or that a problem exists with some
component in the system.
14HPX−018
Liquid / Vapor
5F (5C)**
65 (18) 226 / 140
70 (21) 244 / 141
75 (24) 263 / 142
80 (27) 283 / 143
85 (29) 302 / 144
90 (32) 328 / 145
95 (35) 351 / 146
100 (38) 376 / 147
105 (41) 402 / 148
110 (38) 430 / 149
115 (45) 465 / 150
60 (15) 346 / 139
50 (10) 323 / 117
40 (4) 306 / 98
30 (−1) 278 / 84
20 (−7) 273 / 66
*IMPORTANT These are most−popular−match−up pressures. Indoor match up and indoor load cause pressures to vary.
**Temperature of the air entering the outside coil (outdoor ambient temperature).
°F
−40
−35
−30
−25
−20
−15
−10
−5
0
5
10
15
20
25
30
35
40
45
50
55
506377−01 11/09
IMPORTANT
14HPX−024 14HPX−030
Liquid / Vapor Liquid / Vapor
233 / 137 238 / 138
252 / 138 263 / 139
271 / 140 279 / 139
292 / 141 299 / 140
314 / 142 324 / 141
338 / 143 340 / 142
361 / 145 375 / 145
387 / 146 397 / 145
412 / 147 424 / 147
441 / 148 454 / 150
471 / 151 485 / 150
352 / 138 338 / 137
331 / 114 334 / 112
304 / 99 312 / 93
299 / 80 302 / 74
283 / 66 280 / 53
Table 11. HFC−410A Temperature
°C Psig
−40.0 11.6
−37.2 14.9
−34.4 18.5
−31.7 22.5
−28.9 26.9
−26.1 31.7
−23.3 36.8
−20.6 42.5
−17.8 48.6
−15.0 55.2
−12.2 62.3
−9.4 70.0
−6.7 78.3
−3.9 87.3
−1.1 96.8
1.7 107
4.4 118
7.2 130
10.0 142
12.8 155
14HPX−036 14HPX−042
Liquid/ Vapor Liquid / Vapor
Cooling
220 / 138 223 / 125
236 / 140 241 / 130
256 / 141 261 / 134
276 / 142 282 / 138
298 / 143 302 / 139
321 / 144 326 / 140
344 / 144 349 / 141
369 / 146 374 / 142
394 / 147 399 / 143
421 / 148 428 / 145
449 / 149 455 / 146
Heating
350 / 134 373 / 139
331 / 117 363 / 117
313 / 97 348 / 97
298 / 83 336 / 74
284 / 66 322 / 64
Pressure (Psig)
°F
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
150
Page 20
14HPX−048 14HPX−060
Liquid / Vapor Liquid / Vapor
231 / 136 243 / 136
248 / 139 263 / 137
271 / 140 282 / 138
291 / 142 306 / 139
312 / 143 327 / 140
335 / 144 351 / 141
359 / 145 376 / 142
384 / 146 401 / 143
411 / 148 426 / 145
439 / 149 452 / 146
468 / 150 484 / 148
355 / 130 351 / 117
336 / 113 333 / 105
315 / 88 316 / 88
296 / 72 308 / 70
286 / 64 300 / 61
°C Psig
15.6 170
18.3 185
21.1 201
23.9 217
26.7 235
29.4 254
32.2 274
35.0 295
37.8 317
40.6 340
43.3 365
46.1 391
48.9 418
51.7 446
54.4 476
57.2 507
60.0 539
62.8 573
65.6 608