Hitachi Outdoor Unit Set-Free FSXNK

BrandHitachi Model NoSet-Free FSXNK

Outdoor Unit|Set-Free FSXNK



Energy saving
Capable of impressively low noise levels with noise reduction preference mode (option)

Flexibility of Installation
Compact and light design and flexible refrigerant piping

Comfort and Reliability
Capable of impressively low noise levels with noise reduction preference mode (option)

Control by Network System

Off coil temperature control

Capable of Heat Recovery and 2-pipe Heat Pump Operations


New Type DC Inverter Scroll Compressor

Improved Intermediate Pressure Performance

The intermediate pressure performance is drastically improved by using a release valve and optimizing orbiting scroll lifting force in the improved new compression mechanism. Therefore, intermediate pressure performance is largely improved for energy-saving.

Relese Valve adoption prevents over compression

Orbiting scroll lifting force optimization has archieved leakage loss reduction


Capacity Control by 1 Hz

Performance is greatly improved by the high efficiency DC inverter compressor and 100% load compressor, and loss-less energy saving operation is achieved (depending on the building).


Self-demand Control

A newly developed self-demand function has largely improved energy-saving effects.
Since the current is self-detected and demand control performed automatically, no signal wiring work is required. Conventional demand control using demand signals is also available, and you can select various operations as required.


Compact and Light Design

Transportation and Handling using Elevator

The elevator can be used to transport the base unit separately.

Improvement of Workability

The piping connection work is newly available from the refrigerant piping outlet
(right bottom side of the front cover) in addition to three directions (front, rear or bottom) from the bottom base.

A new piping outlet is provided on the lower right side of the front cover and so the piping connection kit can be installed at the lower position.
This makes an easy and clear installation of the piping from multiple outdoor units possible.

More Flexible Refrigerant Piping Work

Improved flexibility of design by increasing the total pipe length to 1,000 m max.

ï¼»1ï¼½Max. piping length 165m*1
ï¼»2ï¼½Between first branch and indoor unit 90m or less*2
ï¼»3ï¼½Height difference between highest and lowest indoor units 30m or less
ï¼»4ï¼½Height difference between outdoor and indoor units 50m*3
Sales on order 90m or less*2*4
ï¼»5ï¼½Max. length between branch from indoor units 40m


For 100m or more, the pipe diameter will be one size larger.
There’re restrictions for connectable indoor units and refrigerant amount.
Please refer to technical manual for details.
In case the outdoor unit is installed at a higher level than indoor units.
If the outdoor unit is installed lower than indoor units, the maximum height difference is 40m.
In case the outdoor unit is installed at a higher level than indoor units, and only when it is a base unit.

Rotational Operation*1 to Distribute Load of Outdoor Units

Regulating the operation time of each outdoor unit leads to load reduction on compressor.*2 During multiple unit operation, the same rotation frequency of inverter compressor results in an equivalent load on each compressor. Therefore, outdoor unit endurance is improved.


At least 2 outdoor units are required for this function.
Comparison between rotation operation function and non-rotation operation function based on the same system.

Backup Operation Function for Emergency

The Backup Operation Function prevents the system from coming to a complete stop when outdoor unit failure occurs.*1 Emergency operation starts with the remote control switch after an alarm.*3


At least 2 outdoor units are required for this function.
Emergency operation can be performed within 8 hours after unit stoppage. After 8 hours pass from unit stoppage, emergency operation can not be performed.
Emergency operation can be performed when the specified alarm code occurs. Refer to “Alarm Code for Emergency Operation”.

Noise Reduction Preference Mode (Optional Function)

With the new Noise Reduction Preference Mode, the sound pressure level for a particular time zone can be set based upon the usage environment.*1 Therefore, the operation/management of air conditioners is facilitated in areas where the noise level at night time is restricted by laws and regulations.


The range of performance and operation is restricted, because the rotation frequency of the compressor and outdoor fan is forcibly decreased.

Automatic Simple Judgement System for Refrigerant Amount

Use this automatic judgement function to check whether or not the refrigerant amount is sufficient in one refrigerant cycle.

Factor for Judgement

The appropriate refrigerant amount is calculated based upon the following data.


Refrigerant over-charging is not detected. Over-charging can be detected by gradually adding refrigerant from the under-charged state at test run or when refrigerant leakage occurs.
This function does not provide automatic refrigerant charging.
The adjustment (estimate) is changed according to the operation condition
(the number of operating units and temperature).

High External Static Pressure

The outdoor units provide external static pressure up to 60Pa by setting at site for installation on each floor of the building.