Mitsubishi Electric CITY MULTI CMB-WM1016V-AB Installation Manual Download Page 10

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4. Connecting refrigerant pipes and drain pipes

4.1. Connecting refrigerant pipes

1. Be sure to use non-oxidative brazing where necessary. If you do not use non-oxi-

dative brazing, it may clog the pipes.
When brazing the outdoor unit connecting port of HBC controller, supply nitrogen
gas into the pipe between the outdoor unit and HBC controller.

2. After completing pipe connection, support the pipes to ensure that load is not

imparted to the HBC controller’s end connections.

3. When using mechanical couplings, use the ones that meet ISO14903.
4. Support the on-site pipes near the HBC controller at 0.5-meter intervals or less,

and at 2-meter intervals or less in other areas.

Warning:

When installing and moving the unit, do not charge it with refrigerant other
than the refrigerant (R410A or R32) specified on the unit.

- Mixing of a different refrigerant, air, etc. may cause the refrigerant cycle to mal-

function and result in severe damage.

Caution:

•

Use refrigerant piping made of phosphorus deoxidized copper and copper
alloy seamless pipes and tubes. In addition, be sure that the inner and
outer surfaces of the pipes are clean and free of hazardous sulphur,
oxides, dust/dirt, swarf, oils, moisture, or any other contaminants.

- R410A and R32 are high-pressure refrigerants and can cause the existing

piping to burst.

•

Store the piping to be used during installation indoors and keep both ends
of the piping sealed until just before brazing. (Store elbows and other joints
in a plastic bag.)

- If dust, dirt, or water enters the refrigerant cycle, deterioration of the oil and

compressor failure may result.

- Infiltration of a large amount of mineral oil may cause the refrigerant oil to

deteriorate.

•

Do not vent R410A and R32 into the atmosphere.

1. Size of HBC controller’s end connection piping

[Fig. 4.1.2] (P.3)

Note:
•

Be sure to use non-oxidative brazing.

*1. Connection of multiple indoor units with one connection (or joint pipe)

•

Total capacity of connectable indoor units: Less than 80

•

Number of connectable indoor units: Maximum 3 Sets

•

Twinning pipe is field supplied.

*2. PURY-(E)P-400YNW/PURY-(E)M400YNW model or larger requires a

connection of two main-HBC controllers in parallel.

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 controller) completely.
How to handle stop valves is described on each outdoor unit.

Precautions for HBC controller combinations

Refer to [Fig. 4.2.1] for the positioning of twinning pipes.

[Fig. 4.2.1] (P.3)

Slope of twinning pipes (high-pressure side and low-pressure side)
Make sure the slope of the twinning pipes are at an angle within ±15° to the ground.
If the slope exceeds the specified angle, it may cause lack of capacity.

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 (R410A or 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. 4.2.2] (P.3)

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 controller 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.

HBC CONTROLLER

Unit model

Model name

High pressure

side

Low pressure

side

tdoor