Lennox 10ACE Series Installation Instructions Manual page 9

Charge Using Approach Method (TXV Systems)
− Outdoor Temperature >65°F (18°C)
The following procedure is intended as a general guide and
is for use on expansion valve (TXV) systems only. For best
results, indoor temperature should be 70°F (21°C) to 80°F
(26°C). Monitor system pressures while charging.
1. Record outdoor ambient temperature using a digital
thermometer.
2. Attach high pressure gauge set and operate unit for
several minutes to allow system pressures to stabilize.
3. Compare stabilized pressures with those provided in
table 7, Normal Operating Pressures."
IMPORTANT
Use table 7 to help perform maintenance checks.
Table 7 is not a procedure for charging the system.
Minor variations in these pressures may be due to
differences in installations. Significant deviations
could mean that the system is not properly charged
or that a problem exists with some component in the
system.
Pressures higher than those listed indicate that the
system is overcharged. Pressures lower than those
listed indicate that the system is undercharged.
Verify adjusted charge using the approach method.
NOTE − For best results, use the same digital ther-
mometer to check both outdoor ambient and liquid
temperatures.
4. Check the liquid line temperature. The difference be-
tween the ambient and liquid temperatures should
match values given in table 6. Loss of charge results
in low capacity and efficiency.
5. If the values do not agree with the those in table 6, add
refrigerant to lower the approach temperature, or re-
cover refrigerant from the system to increase the ap-
proach temperature.
10ACE Model
Temp. °F (°C)
Approach Value is the Liquid Line Temperature minus Outdoor Ambi-
ent Temperature [ºF (ºC) + 1ºF (0.5ºC)]
Normal Operating Pressures*
10ACE−024
Temp5F Temp5F
(5C)** Liq. Suc.
Expansion Valve
65 (18) 163 70
75 (24) 193 71
85 (29) 225 72
95 (35) 260 73
105 (41) 298 74
110 (43) 318 75
115 (45) 338 75
Fixed Orifice
65 (18) 165 63
75 (24) 194 67
85 (29) 224 70
95 (35) 257 73
105 (41) 293 76
110 (43) 313 78
115 (45) 332 79
* Values shown are typical pressures (in. psig +2psig); indoor unit
match up, indoor air quality equipment, and indoor load will cause
the pressures to vary.
** Temperature of the air entering the outside coil.
Page 9
Table 6
Approach Values
−024 −036 −048
18 (10) 11 (6) 8 (4.5)
Table 7
10ACE−036 10ACE−048
Liq. Suc. Liq. Suc.
162 70 159 71
187 74 188 72
219 75 220 73
253 77 251 76
291 79 290 77
310 80 309 78
329 81 328 79
168 67 163 68
195 71 190 71
224 75 220 74
255 78 251 77
289 82 288 79
305 83 307 80
324 84 325 82
−060
13 (7)
10ACE−060
Liq. Suc.
170 74
201 76
234 77
270 79
309 79
331 80
351 81
189 72
203 74
233 77
265 79
301 82
319 83
339 84
10ACE SERIES