Mitsubishi Heavy Industries SRK20ZIX-S Service Manual page 31

Model 40, 50, 60
This unit contains factory charged refrigerant covering 15m of refrigerant piping and additional refrigerant charge on the installation site is not required for
an installation with up to 15m refrigerant piping.
When refrigerant piping exceeds 15m, additionally charge an amount calculated from the pipe length and the above table for the portion in excess of 15m.
If an existing pipe system is used, a required refrigerant charge volume will vary depending on the liquid pipe size. For further information, please see
"5. UTILIZATION OF EXISTING PIPING."
Formula to calculate the volume of additional refrigerant required
Additional charge volume (kg) = { Main length (m) – Factory charged volume 15 (m) } x 0.02 (kg/m)
For an installation measuring 15 m or shorter in pipe length, please charge the refrigerant volume charged for shipment at the factory, when you recharge refrigerant after servicing etc.
(2) Charging refrigerant
Since R410A refrigerant must be charged in the liquid phase, you should charge it, keeping the container cylinder upside down or using a refrigerant cylinder equipped with a siphon tube.
Charge refrigerant always from the liquid side service port with the operation valve shut. When you find it difficult to charge a required amount, fully open the outdoor unit valves on both liquid and gas sides and charge refrigerant
from the gas (suction) side service port, while running the unit in the cooling mode. In doing so, care must be taken so that refrigerant may be discharged from the cylinder in the liquid phase all the time. When the cylinder valve
is throttled down or a dedicated conversion tool to change liquid-phase refrigerant into mist is used to protect the compressor, however, adjust charge conditions so that refrigerant will gasify upon entering the unit.
In charging refrigerant, always charge a calculated volume by using a scale to measure the charge volume.
When refrigerant is charged with the unit being run, complete a charge operation within 30 minutes. Running the unit with an insufficient quantity of refrigerant for a long time can cause a compressor failure.
NOTE
Put down the refrigerant volume calculated from the pipe length onto the caution label attached on the back side of the service panel.
8) Heating and condensation prevention
(1) Dress refrigerant pipes (both gas and liquid pipes) for heat insulation and prevention of dew condensation.
- Improper heat insulation/anti-dew dressing can result in a water leak or dripping causing damage to household effects, etc.
(2) Use a heat insulating material that can withstand 120
deterioration.
- All gas pipes must be securely heat insulated in order to prevent damage from dripping water that comes from the condensation formed on them during a cooling operation
or personal injury from burns because their surface can reach quite a high temperature due to discharged gas flowing inside during a heating operation.
- Wrap indoor units' flare joints with heat insulating parts (pipe cover) for heat insulation (both gas and liquid pipes).
- Give heat insulation to both gas and liquid side pipes. Bundle a heat insulating material and a pipe tightly together so that no gaps may be left between them and wrap them
together with a connecting cable by a dressing tape.
- Both gas and liquid pipes need to be dressed with 20 mm or thicker heat insulation materials above the ceiling where relative humidity exceeds 70%.
3. DRAIN PIPING WORK
Execute drain piping by using a drain elbow and drain
grommets supplied separately as optional parts, where
water drained from the outdoor unit is a problem.
Where you are likely to have several days of sub-zero
temperatures in a row, do not use a drain elbow and
drain grommets. (There is a risk of drain water
freezing inside and blocking the drain.)
per meter of refrigerant piping (liquid pipe 6.35) for shipment at the factory (kg)
0.02
or a higher temperature. Poor heat insulating capacity can cause heat insulation problems or cable
Drain elbow
covered without additional refrigerant charge
1.40 15
*When an additional charge volume calculation result is negative,
it is not necessary to charge refrigerant additionally.
CAUTION
Do not put a grommet
on this hole.
This is a supplementary
drain hole to discharge
drain water, when a large
quantity of it is gathered.
Drain hose
Grommet To be procured on the installer's part
Band (accessory)
Pipe cover (accessory)
Wires for connecting indoor
Exterior tape
and outdoor units
Gas piping
Liquid piping
Insulation
When condensed water needs to be
led to a drain, etc., install the unit on
a flat base (supplied separately as an
optional part) or concrete blocks.
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