Friedrich FPHMR18A3A Service Manual page 53

Outdoor Units
Additional Refrigerant Charge
Although refrigerant has been charged into this unit, additional refrigerant charge may be required according to the piping length.
The additional refrigerant precharge quantity should be determined and charged into the system according to the following
procedure.
For configurations containing a mix of 7‑18k indoor units:
1. Determine the Length of 1/4" Liquid line set used in the Installation (L).
2. Use table 433.1 to determine how much additional refrigerant is required.
For configurations includng 24k units
1. Determine the Length of 1/4" Liquid line set used in the Installation. (L1)
2. Determine the Length of 3/8" Liquid line set used in the Installation. (L2)
3. Use table 433.1 to determine how much additional refrigerant is required.
X is the additonal refrigerant required for servicing according to the installation piping length.
If X is less than zero, no additional refrigerant is required.
Record the additional refrigerant quantity in order to facilate future maintenance and servicing activities.
Outdoor Indoor Unit
Unit Configuration
18k 7k‑18k
24k 7k‑18k
36k 7k‑18k
7k‑24k
42k 7k‑18k
7k‑24k
53
INSTALLATION
Pre‑Charged (CF) Correction
Refigerant weight Factor for 3/8 line
before shipping set (Only used with
24k indoor units)
63.49 oz. N/A
81.13 oz N/A
105.82 oz N/A
105.82 oz 15.68
120 oz N/A
120 oz 20
Table 433.1 ( Determining Additional Required Refrigerant)
(P) pre‑charged 1/4" Additional refrigerant charge
line set length required (in ounces)
50 X = (L‑P) * .16
75 X = (L‑P) * .16
100 X = (L‑P) * .16
100 X = (L1 * .16) +(L2 *.38) ‑ CF
125 X = (L‑P) * .16
125 X = (L1 * .16) +(L2 *.38) ‑ CF