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Note:
•

Be sure to use non-oxidative brazing.

4.2. Refrigerant piping work

After connecting the refrigerant pipes of the outdoor units with the outdoor units’ stop
valves remained fully closed, evacuate vacuum from the outdoor units’ stop valve
service ports.
After completing the above, open the outdoor units’ stop valves. This connects the
refrigerant circuit (between outdoor and HBC) completely.
How to handle stop valves is described on each outdoor unit.

Notes:
•

Have a fire extinguisher nearby before brazing work.

•

Provide no-smoking signs at the brazing workplace.

•

After pipe connection, be sure to check that there is no gas leakage, using
a leak detector or soap-and-water solution.

•

Before brazing the refrigerant piping,

always wrap the piping on the main

body, and the thermal insulation piping, with damp cloths to prevent heat
shrinkage and burning the thermal insulation tubing.

Take care to ensure

that the flame does not come into contact with the main body itself.

•

Do not use leak-detection additives.

•

Straight run of pipe connecting twinning pipe is 500 mm or more.

•

Piping work shall be kept to a minimum.

•

The pipes shall be protected from physical damage.

Warning:

Do not mix anything other than the specified refrigerant R32 into the
refrigerating cycle when installing or moving. Mixing air may cause the
refrigerating cycle to reach abnormally high temperature, resulting in burst
pipes.

Caution:

Cut the tip of the outdoor unit piping, remove the gas, and then remove the
brazed cap.

[Fig. 4.2.1] (P.4)

4.3. Insulating pipes

Be sure to add insulation work to piping by covering high-temperature pipe and low-
temperature pipe separately with enough thickness heat-resistant polyethylene
foam, so that no gap is observed in the joint between the HBC and insulating
material, and insulating materials themselves. When insulation work is insufficient,
there is a possibility of condensation. Pay special attention to insulation work in the
ceiling plenum.

[Fig. 4.3.1] (P.4)

•

Insulation materials for the pipes to be added on site must meet the following
specifications:

•

Installation of pipes in a high-temperature high-humidity environment, such as
the top floor of a building, may require the use of insulation materials thicker than
the ones specified in the chart above.

•

When certain specifications presented by the client must be met, ensure that
they also meet the specifications on the chart above.

•

The brazed connections must be covered with insulation, with its seam facing
upward and fastened with the bands.

4.4. Additional refrigerant charge

Notes:
•

Charge refrigerant in a liquid state.

•

Do not use a charging cylinder when charging refrigerant.

- The use of a charging cylinder may change the composition of the refrigerant

and lead to a performance drop.

The table below summarizes the factory-charged amount of refrigerant, the
maximum amount of refrigerant to be added on site, and the maximum total amount
of refrigerant in the system.

Both refrigerant overcharge and undercharge will cause problems. Charge the
system with the proper amount of refrigerant.
Record the added refrigerant amount on the label attached to the control box panel
for future servicing.

Calculation of the amount of additional refrigerant

•

The amount of refrigerant to be added depends on the size and the total
length of the high-pressure piping and liquid piping.

•

Calculate the amount of refrigerant to be charged according to the formula
below.

•

Round up the calculation result to the nearest 0.1 kg (0.1 oz).

•

The refrigerant does not need to be added for the indoor units in a Hybrid
City Multi system.

To outdoor unit

End connection (brazing)

Main-HBC