Panasonic U-72MF2U9 Technical Data Manual page 34

2. System Design
2-2. Example of Tubing Size Selection and Refrigerant Charge Amount
Additional refrigerant charging
Based on the values in Tables 2, 3, 4, 6, 9 and 10, use the liquid tubing size and length, and calculate the amount of additional
refrigerant charge using the formula below.
Unit of account (oz)
Required additional
refrigerant charge (oz)
or
g
Unit of account ( )
Required additional
refrigerant charge (g)
1
(a) : Liquid tubing
(b) : Liquid tubing
(c) : Liquid tubing
(d) : Liquid tubing
(e) : Liquid tubing
2
(f) : Liquid tubing
Charging procedure
Be sure to charge with R410A refrigerant in liquid form.
1. After performing a vacuum, charge with refrigerant from the liquid tubing side.
At this time, all valves must be in the "fully closed" position.
2. If it was not possible to charge the designated amount, operate the system in Cooling mode while charging with refrigerant from the gas
3
tubing side. (This is performed at the time of the test run. For this, all valves must be in the "fully open" position. However, if only one
outdoor unit is installed, a balance tube is not used. Therefore, leave the valves fully closed.)
Charge with R410A refrigerant in liquid form.
With R410A refrigerant, charge while adjusting the amount being fed a little at a time in order to prevent liquid refrigerant from backing up.
After charging is completed, turn all valves to the "fully open" position.
Replace the tubing covers as they were before.
4
CAUTION
5
6
7
Suction tube
8
Use a flathead
screwdriver and open
by turning the part with
the screw groove to the
right, from " –" to " | ".
9
Necessary Amount of Additional Refrigerant Charge Per Outdoor Unit
=
+ 3.93 × (a) + 2.78 × (b) + 1.99 × (c) + 1.38 × (d) + 0.602 × (e) + 0.279 × (f)
+ Necessary amount of additional refrigerant charge for all indoor unit cooling capacity
+ 0.763 × (A) + 0.441 × (B) + 0.333 × (C) + 0.226 × (D) + 0.129 × (E)
Necessary Amount of Additional Refrigerant Charge Per Outdoor Unit
+ 366 × (a) + 259 × (b) + 185 × (c) + 128 × (d) + 56 × (e) + 26 × (f)
=
+ Necessary amount of additional refrigerant charge for all indoor unit cooling capacity
+ 71 × (A) + 41 × (B) + 31 × (C) + 21 × (D) + 12 × (E)
Total length of ø7/8" (ft.) or (m)
Total length of ø3/4" (ft.) or (m)
Total length of ø5/8" (ft.) or (m)
Total length of ø1/2" (ft.) or (m)
Total length of ø3/8" (ft.) or (m)
Total length of ø1/4" (ft.) or (m)
1. R410A additional charging absolutely must be done through liquid charging.
2. The R410A refrigerant cylinder has a gray base color, and the top part is pink.
3. The R410A refrigerant cylinder includes a siphon tube. Check that the siphon tube is present.
(This is indicated on the label at the top of the cylinder.)
4. Due to differences in the refrigerant, pressure, and refrigerant oil involved in installation, it is
not possible in some cases to use the same tools for R22 and for R410A.
For type 72
Discharge tube
(For type 72/96)
Use a hex wrench (width
15/64 inch (6mm)) and
turn to the left to open.
(A) : Discharge tubing Total length of ø1-1/8" (ft.) or (m)
(B) : Discharge tubing Total length of ø7/8" (ft.) or (m)
(C) : Discharge tubing Total length of ø3/4" (ft.) or (m)
(D) : Discharge tubing Total length of ø5/8" (ft.) or (m)
(E) : Discharge tubing Total length of ø1/2" (ft.) or (m)
For type 96
Liquid tube
(For type 120/144) Use a hex wrench (width
Use a flathead 5/32 inch (4mm)) and
screwdriver and open turn to the left to open.
by turning the part with
the screw groove to the
right, from " –" to " | ".
16
2 - 18
Design of 3WAY VRF SYSTEM
For type 120/144
Balance tube
Use a flathead
screwdriver and open
by turning the part with
the screw groove to the
right, from " –" to " | ".