Lennox International Inc. 4HP18LT - Manual (Page 15)

506470-01 Issue 1007
5. Compare the subcooling value with those shown in Table
7. If subcooling is greater than shown, recover some
refrigerant. If subcooling is less than shown, add some
refrigerant.
Charge Using Approach Method (TXV System) - Outdoor
Temperatures 65°F or Above
The following procedure is intended as a general guide and
is for use on expansion valve systems only. For best results,
indoor temperature should be 70°F to 80°F. Monitor system
pressures while charging.
1. Record outdoor ambient temperature usig 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
8. Minor variations in these pressures may be expected
due to differences in installations. Significant differences
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.
4. Use the same digital thermometer to check liquid line
temperature.
5. Subtract the outdoor ambient temperature from the liquid
line temperture to determine the approach temperature.
Page 15
Table 6
Subcooling Values
Table 5
R410A Temperature/Pressure Chart
T e m p .
(F
P re s s u re
P s ig
T e m p .
(F
P re s s u re
P s ig
T e m p .
(F
P re s s u re
P s ig
3 2 1 0 0 .8 7 4 2 1 4 .0 1 1 6 3 9 6 .0
3 3 1 0 2 .9 7 5 2 1 7 .4 1 1 7 4 0 1 .3
3 4 1 0 5 .0 7 6 2 2 0 .9 1 1 8 4 0 6 .7
3 5 1 0 7 .1 7 7 2 2 4 .4 1 1 9 4 1 2 .2
3 6 1 0 9 .2 7 8 2 2 8 .0 1 2 0 4 1 7 .7
3 7 1 1 1 .4 7 9 2 3 1 .6 1 2 1 4 2 3 .2
3 8 1 1 3 .6 8 0 2 3 5 .3 1 2 2 4 2 8 .8
3 9 1 1 5 .8 8 1 2 3 9 .0 1 2 3 4 3 4 .5
4 0 1 1 8 .0 8 2 2 4 2 .7 1 2 4 4 4 0 .2
4 1 1 2 0 .3 8 3 2 4 6 .5 1 2 5 4 4 5 .9
4 2 1 2 2 .6 8 4 2 5 0 .3 1 2 6 4 5 1 .8
4 3 1 2 5 .0 8 5 2 5 4 .1 1 2 7 4 5 7 .6
4 4 1 2 7 .3 8 6 2 5 8 .0 1 2 8 4 6 3 .5
4 5 1 2 9 .7 8 7 2 6 2 .0 1 2 9 4 6 9 .5
4 6 1 3 2 .2 8 8 2 6 6 .0 1 3 0 4 7 5 .6
4 7 1 3 4 .6 8 9 2 7 0 .0 1 3 1 4 8 1 .6
4 8 1 3 7 .1 9 0 2 7 4 .1 1 3 2 4 8 7 .8
4 9 1 3 9 .6 9 1 2 7 8 .2 1 3 3 4 9 4 .0
5 0 1 4 2 .2 9 2 2 8 2 .3 1 3 4 5 0 0 .2
5 1 1 4 4 .8 9 3 2 8 6 .5 1 3 5 5 0 6 .5
5 2 1 4 7 .4 9 4 2 9 0 .3 1 3 6 5 1 2 .9
5 3 1 5 0 .1 9 5 2 9 5 .1 1 3 7 5 1 9 .3
5 4 1 5 2 .8 9 6 2 9 9 .4 1 3 8 5 2 5 .8
5 5 1 5 5 .5 9 7 3 0 3 .8 1 3 9 5 3 2 .4
5 6 1 5 8 .2 9 8 3 0 8 .2 1 4 0 5 3 9 .0
5 7 1 6 1 .0 9 9 3 1 2 .7 1 4 1 5 4 5 .6
5 8 1 6 3 .9 1 0 0 3 1 7 .2 1 4 2 5 5 2 .3
5 9 1 6 6 .7 1 0 1 3 2 1 .8 1 4 3 5 5 9 .1
6 0 1 6 9 .6 1 0 2 3 2 6 .4 1 4 4 5 6 5 .9
6 1 1 7 2 .6 1 0 3 3 3 1 .0 1 4 5 5 7 2 .8
6 2 1 7 5 .5 1 0 4 3 3 5 .7 1 4 6 5 7 9 .8
6 3 1 7 8 .5 1 0 5 3 4 0 .5 1 4 7 5 8 6 .8
6 4 1 8 1 .6 1 0 6 3 4 5 .3 1 4 8 5 9 3 .8
6 5 1 8 4 .3 1 0 7 3 5 0 .1 1 4 9 6 0 1 .0
6 6 1 8 7 .7 1 0 8 3 5 5 .0 1 5 0 6 0 8 .1
6 7 1 9 0 .9 1 0 9 3 6 0 .0 1 5 1 6 1 5 .4
6 8 1 9 4 .1 1 1 0 3 6 5 .0 1 5 2 6 2 2 .7
6 9 1 9 7 .3 1 1 1 3 7 0 .0 1 5 3 6 3 0 .1
7 0 2 0 0 .6 1 1 2 3 7 5 .1 1 5 4 6 3 7 .5
7 1 2 0 3 .9 1 1 3 3 8 0 .2 1 5 5 6 4 5 .0
7 2 2 0 7 .2 1 1 4 3 8 5 .4
7 3 2 1 0 .6 1 1 5 3 9 0 .7
7 2 2 0 7 .2 1 1 4 3 8 5 .4
7 3 2 1 0 .6 1 1 5 3 9 0 .7