Oil Charge; Heat Pump Unit; Maintenance - Lennox HP21 Unit Information

ent temperature is the approach temperature.
Approach temperature should match the values
shown in table 16. Add refrigerant to reduce approach
temperature and remove refrigerant to increase ap-
proach temperature.
TABLE 16
Model
HP21−411/413, HP21−36−230/233
HP21−511/513, HP21−48−230/233
HP21−651/653, HP21−60−230/233
FIGURE 22
OUTDOOR TEMPERATURE BELOW 60°F
(steps 6 through 8)
6− It is not recommended that the system be charged be-
low 60°F. If charging below 60°F is required, the most
reliable method is to weigh in the charge listed on the
unit nameplate. This amount (table 14) will be correct
for a system with a line set of 25 feet. If line set is longer
or shorter than 25 feet, add or remove refrigerant as
shown in table 15.
7− If ambient temperature is less than 60°F (10°C), sys-
tem should be charged using the subcooling method.
Air flow will need to be restricted to achieve pressures
in the 200−250 psig range (See figure 22.) These high-
er pressures are necessary for checking the
subcooling temperature. Block equal sections of air in-
take panels, moving obstructions sideways as shown
until liquid pressure rises above 200 psig.
8− Read liquid line pressure from gauge and convert to
condensing temperature using standard R−22 temper-
ature/pressure conversion chart (or conversion scale
on gauge.) The difference between the liquid line tem-
perature and the
subcooling (subcooling = conversion temperature mi-
nus liquid line temperature).
temperature should approximate the values given in
table 17. Add refrigerant to increase subcooling and re-
move refrigerant to reduce subcooling.
TABLE 17
Model
HP21−410/510/650/36/48/60
Liquid Temp Minus Am-
°
bient Temp. ( F)
9 + 2
7 + 2
10 + 2
BLOCKING
OUTDOOR
COIL
OUTDOOR COIL SHOULD
BE BLOCKED ONE SIDE
AT A TIME WITH CARD−
BOARD OR PLASTIC
SHEET UNTIL PROPER
TESTING PRESSURES
ARE REACHED.
CARDBOARD OR
PLASTIC SHEET
conversion temperature
The subcooling
°
Subcooling F
10 + 3
9− When unit is properly charged, liquid line pressures
should approximate those given in table 18.
D−Oil Charge
Factory oil charge in all HP21 series units is 70 fl. oz. Re-
placement oil charge is 66 fl.oz.
NORMAL OPERATING PRESSURES
OUTDOOR
COIL
ENTERING
MODE
TEMP.
COOLING
EXPANSION
VALVE
ONLY
105
HEATING
ALL UNITS
NOTE − Liquid line pressure in heating mode may vary more than +10
PSIG depending on unit matchup. All pressures are with unit operating
on high speed. Indoor return air 80°F for cooling.
V−Maintenance
At the beginning of each heating or cooling season, the
system should be cleaned as follows:
A−Heat Pump Unit
1− Clean and inspect outdoor coil. (Coil may be flushed
with a water hose.)
2− Rotate fan to check for frozen bearings or binding.
Outdoor fan motor is prelubricated and sealed with
plugs. No further lubrication is required.
3− Visually inspect all connecting lines, joints and coils for
evidence of oil leaks.
4− Check all factory and field−installed wiring for loose
connections.
5− Check voltage supply at disconnect (unit not operat-
ing.) Voltage must be within range listed on unit rating
plate. If not, do not start equipment until the power
company has been consulted and the voltage condi-
is
tion corrected.
Check for correct voltage at unit (unit operating).
6− Check fan motor amp-draw.
Unit nameplate_________Actual_________.
7− Check compressor amp-draw.
Unit nameplate_________Actual_________.
NOTE − If insufficient heating or cooling occurs, the unit
should be gauged and refrigerant charge checked.
Page 25
ALL UNITS
(step 9)
TABLE 18
HP21−411
HP21−511
HP21−413
HP21−513
HP21−48−233 HP21−36−230
HP21−36−230
HP21−36−233 HP21−48−230
LIQ. SUC. LIQ. SUC.
AIR
+ 10 + 5 + 10
PSIG PSIG PSIG PSIG
°
75 F 175 74 177
°
85 F
208 76 190
°
95 F
245 78 228
°
F
277 80 266
°
20 F
180 33 160
°
30 F
191 40 171
°
40 F
206 49 184
°
50 F
225 59 204
HP21−651
HP21−653
HP21−36−233
LIQ.
SUC.
+ 5
+ 5 + 10
PSIG PSIG
80 182 76
84 213 79
86 242 80
88 276 82
32 175 31
40 185 38
50 206 47
62 227 57