7.1 Before Installation
7.1.1 Scope of this manual
This manual describes the procedures for handling, installing and connecting 1UH071-250 units.
Since maximum working pressure is 4.15 MPa or 41.5 bar, pipes of larger wall thickness may be required. Refer to
paragraph " .2. Selection of piping material" on page 10.
Insulation resistance of the compressor
If after installation, refrigerant accumulates in the compressor, the insulation resistance can drop, but if it is at least
1MΩ, then the machine will not break down. Turn the power on and leave it on for 6h. Then, check if the insulation
resistance of the compressor has risen or not.
The compressor will heat up and evaporate any refrigerant in the compressor
Check the following if the ground-fault circuit interrupter is triggered:
Make sure that the interrupter is compatible with high frequencies.
This unit has an inverter, so an interrupter capable of handling high frequencies is needed to prevent malfunction
of the interrupter itself.
7.1.3 Precautions for R410A
• The refrigerant requires strict cautions for keeping the system clean, dry and tight.
- Clean and dry
Foreign materials (including mineral oils or moisture) should be prevented from getting mixed into the system.
• Read "9. Precautions on refrigerant piping" on page 10 carefully and follow these procedures correctly.
• Since R410A is a mixed refrigerant, the required additional refrigerant must be charged in its liquid state. (If the
refrigerant is in state of gas, its composition changes and the system will not work properly).
• The connected indoor units must be indoor units designed exclusively for R410A.
• For installation of the indoor unit (s) , refer to the indoor unit installation manual.
• Illustrations show 1UH140P1ERK outdoor unit type. Other types also follow this installation manual.
• This outdoor unit requires the pipe branching kit (optional) when used as the outdoor unit for the simultaneous
operation system. Refer to catalogues for details.
• Never operate the unit with a damaged or disconnected discharge thermistor and suction thermistor, burning of
the compressor may occur.
• Be sure to confirm the model name and the serial no. of the outer (front) plates when attaching/detaching the
plates to avoid mistakes.
• When closing the service panels, take care that the tightening torque does not exceed 4.1 N.M.