R407C CCU Technical Manual MCAC-UTSM-2012-05
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5. Piping between outdoor unit and indoor unit
5.1 Preparation before Installation
Check the height difference between the indoor unit and the outdoor unit, and check the length and number of
bends of the refrigerant pipeline, which must meet the following requirements:
Max. Height difference....30m (If the height difference is greater than 5m, it is better to put the outdoor unit
above the indoor unit).
Max. Pipeline length.........50m.
Max. Number of bends....15.
In the piping process, do not let the air, dust or foreign substance intrudes into the pipeline system.
Start piping only after fixing the indoor and outdoor units.
Keep dry when piping. Do not let moist intrude into the pipeline system.
5.2 Procedure of Connecting Pipes
5.2.1 Measure the required length of the connective pipe, and make the pipes in the following procedure:
Connect the indoor unit first, and then connect the outdoor unit.
The pipe bend should be handled carefully, without damaging the pipe.
The valve of the outdoor unit should be closed completely.
Every time when connecting the pipe, screw off the nut at the valve, and connect the flared pipe (within 5 minutes).
If the nut is put away for a long time after being screwed off the valve, dust and other foreign substance may
intrude into the pipeline system and lead to fault. Before connecting the pipe, use the refrigerant to expel air out of
the pipe.
After complete piping, expel air as instructed in the “Expel air” section.
After expelling the air, screw up the nut at the maintenance orifice.
The bend angle shall not exceed 90°.
The bend shall be preferably in the middle of the pipe length, and higher bend radiuses are preferred. Do not
bend the flexible pipe for over 3 times.
Bend the thin-wall connective pipe
When bending the pipe, cut out a notch of the desired size at the bend of the adiabatic pipe, and then expose the
pipe (wrap the pipe with the wrapping tape after bending it).
The radio of the elbow pipe should be as large as possible to prevent flattening or crush.
Use the pipe bender to make close elbow pipe.
Use purchased copper pipe
When the cooper pipe is purchased from the market, be sure to use the heat insulation materials of the same type
(with a thickness of over 9mm).
5.2.2 Lay the pipelines
Drill a hole on the wall, and put the hole sheath and hole cover through the wall.
Place the connective pipe together with the indoor & outdoor connection wires. Use wrapping tape to tie them
tight. Do not let air penetrate into it lest condensation and drips of moist.
Pull the connective wrapped connective pipe from outdoor through the sheath which gets through the wall, and
lead it into the room. Lay out the pipelines carefully to avoid damage.
5.2.3 Make a vacuum of connective pipeline.
5.2.4 After the above steps are completed, the spool of the valve of the outdoor unit should be completely open,
and the refrigerant pipeline of the indoor unit and the outdoor unit should be smooth.
5.2.5. Use leak detector or soap water detect leak carefully to prevent leakage.
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