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1-13. Example of Tubing Size Selection and Refrigerant Charge Amount
Additional refrigerant charging
Based on the values in Tables 1-3, 4, 5, 7, 10-1 and 10-2, 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)
=
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
or
Unit of account (
g
)
Required additional
refrigerant charge (
g
)
=
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
(a) : Liquid tubing
Total length of ø7/8" (ft.) or (m)
(d) : Liquid tubing
Total length of ø1/2" (ft.) or (m)
(b) : Liquid tubing
Total length of ø3/4" (ft.) or (m)
(e) : Liquid tubing
Total length of ø3/8" (ft.) or (m)
(c) : Liquid tubing
Total length of ø5/8" (ft.) or (m)
(f) : Liquid tubing
Total length of ø1/4" (ft.) or (m)
●
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 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.
CAUTION
CAUTION
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
For type 96
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 “|”.
Balance tube
Use a flathead screwdriver and
open by turning the part with the
screw groove to the right, from “–”
to “|”.
Balance tube
Use a flathead screwdriver and
open by turning the part with the
screw groove to the right, from “–”
to “|”.
Gas tube
Use a flathead screwdriver and
open by turning the part with the
screw groove to the right, from “–”
to “|”.
Gas tube
Use a flathead screwdriver and
open by turning the part with the
screw groove to the right, from “–”
to “|”.
Gas tube
Use a flathead screwdriver and
open by turning the part with the
screw groove to the right, from “–”
to “|”.
Liquid tube
Use a hex wrench
(width 5/32 inch (4mm))
and turn to the left to
open.
Liquid tube
Use a hex wrench
(width 5/32 inch (4mm))
and turn to the left to
open.
Liquid tube
Use a hex wrench
(width 5/32 inch (4mm))
and turn to the left to
open.
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