Lennox International Inc. 4HP18LT - Manual (Page 16)

506470-01 Issue 1007
=
_
Outdoor Ambient Temperature °F
Liquid Line Temperature °F
Approach Temperature °F
°
°
°
6. Compare the approach value with those shown in Table
9. If the values do not agree with those provided in Table 8,
add refrigerant to lower the approach temperature or recover
refrigerant from the system to increase the approach
temperature.
Check Charge Using Normal Operating Pressures
Use Table 7 to 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.
Page 16
Table 7
Approach Values for TXV Systems