Maintenance; Outdoor Unit; Indoor Coil; Indoor Unit - Lennox HS25–211 Servise Manual

If weighing facilities are not available or if unit is just
low on charge, the following procedure applies.
The following procedures are intended as a general
guide for use with expansion valve systems only. For
best results, indoor temperature should be between
70 F and 80 F. Outdoor temperature should be 60 F or
above. Slight variations in charging temperature and
pressure should be expected. Large variations may in-
dicate a need for further servicing.
APPROACH METHOD (TXV SYSTEMS)
(Ambient Temperature of 60_F [16_C] or Above)
1– Connect gauge manifold. Connect an upright
HCFC-22 drum to center port of gauge manifold.
IMPORTANT
The following procedure requires accurate read-
ings of ambient (outdoor) temperature, liquid
temperature and liquid pressure for proper charg-
ing. Use a thermometer with accuracy of +2 F and
a pressure gauge with accuracy of +5 PSIG.
2– Record outdoor air (ambient) temperature.
3– Operate indoor and outdoor units in cooling mode.
Allow units to run until system pressures stabilize.
4– Make sure thermometer well is filled with mineral oil
before checking liquid line temperature.
5– Place thermometer in well and read liquid line tem-
perature. Liquid line temperature should be a few de-
grees warmer than the outdoor air temperature.
Table 5 shows how many degrees warmer the liquid
line temperature should be.
Add refrigerant to make the liquid line cooler.
Recover refrigerant to make the liquid line warmer.
6– When unit is properly charged liquid line pressures
should approximate those in table 6.
TABLE 5
APPROACH METHOD – EXPANSION VALVE SYSTEMS
Liquid Line F Warmer Than Outside
Model
HS25–211
HS25–261
HS25–311
HS25–411
HS25–461
HS25–511
HS25–651
HS25–211
OUTDOOR COIL
LIQ. SUC.
ENTERING AIR
+ 10
TEMPERATURE
PSIG PSIG
65 F (TXV)
138
162
75 F (TXV)
85 F (TXV)
189
95 F (TXV) 222
255
105 F (TXV)
(Ambient) Temperature
7+1
7+1
3+1
4+1
5+1
3+1
4+1
NORMAL OPERATING PRESSURES
HS25–261 HS25–311
LIQ. SUC. LIQ.
+ 10 + 10 + 10 + 10
PSIG PSIG PSIG
78 143 73 140
79 167 77 160
80 195 80 186
82 229 82 216
84 263 84 254
Use table 6 as a general guide for performing main-
tenance checks. Table 6 is not a procedure for charg-
ing the system. Minor variations in these pressures
may be expected 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. Used pru-
dently, table 6 could serve as a useful service guide.
D–Oil Charge
Refer toTable 1 on page 5.
VI–MAINTENANCE
At the beginning of each heating or cooling season, the
system should be cleaned as follows:
A–Outdoor Unit
1– Clean and inspect condenser coil. (Coil may be
flushed with a water hose).
2– Visually inspect all connecting lines, joints and
coils for evidence of oil leaks.
If insufficient heating or cooling occurs, the unit
should be gauged and refrigerant charge checked.
B–Indoor Coil
1– Clean coil if necessary.
2– Check connecting lines and coil for oil leaks.
3–Check condensate line and clean if necessary.
C–Indoor Unit
1– Clean or change filters.
2– Adjust blower cooling speed. Check static pressure
drop over coil to determine correct blower CFM. Re-
fer to Lennox Engineering Handbook.
3– Belt Drive Blowers - Check condition/tension.
4– Check all wiring for loose connections.
5– Check for correct voltage at unit.
6– Check amp–draw on blower motor.
Unit nameplate_________Actual_________.
TABLE 6
HS25–411 HS25–461
SUC. LIQ. SUC. LIQ.
+ 10 + 10 + 10 + 10
PSIG PSIG PSIG PSIG
69 136 74 149
74 160 76 176
78 191 78 209
80 225 79 244
81 260 80 275
Page 9
IMPORTANT
IMPORTANT
HS25–511
SUC. LIQ. SUC. LIQ.
+ 10 + 10 + 10 + 10
PSIG PSIG PSIG PSIG
69 138 73 138
72 163 75 164
74 182 76 185
76 222 78 228
78 255 79 260
HS25–651
SUC.
+ 10
PSIG
69
73
74
75
76