Allied Air Enterprises 4HP16LT - Manual (Page 16)

5. Subtract the outdoor ambient temperature from the liquid
line temperture to determine the approach temperature.
506468-01 Page 16
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.
Issue 1004
6. Compare the approach value with those shown in Table
8. 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.
=
_
Outdoor Ambient Temperature °F
Liquid Line Temperature °F
Approach Temperature °F
°
°
°
Table 8
Approach Values for TXV Systems
Approach value is the liquid line temperature minus the outdoor
ambient temperature (±1°F).
Note: For best results, use the same digital thermometer to check
both outdoor ambient and liquid temperatures.