The brief
When construction stopped, the indoor units, refrigerant pipework, drainage and control networks had already been installed in the building. After almost seven years out of service, we needed to determine which parts of this infrastructure could be safely reused and which required restoration or replacement
Complete removal would have meant losing a substantial part of the investment already made. We therefore proposed comprehensive diagnostics, restoration of the networks and selection of compatible equipment, rather than starting from scratch
What the diagnostics revealed
During the period out of service, some of the pipework had suffered mechanical damage during other construction work. Some sections had developed leaks, allowing ambient air, moisture, dust and construction debris to enter the pipework
There was another problem: the indoor unit manufacturer had discontinued supply of this equipment, while the new outdoor units belonged to a different generation of systems
Compatibility of old and new units
We checked which current outdoor units could operate with the installed indoor units and supported the required communication protocol. Compatibility was established through both documentation reviews and practical tests with different control systems
As a result, we selected a solution that allowed all the indoor units to be retained and connected to new outdoor equipment
Restoring the refrigerant pipework
The existing pipework could not simply be connected to the new equipment. A dedicated restoration procedure was developed for it
Defect inspection
Locating damaged sections and leaking joints
Cleaning
Removing dust, moisture and foreign contaminants
Drying
Preparing the pipework after prolonged exposure to ambient air
Evacuation
Multi-stage treatment with residual moisture monitoring
Pressure testing
Leak testing with high-pressure nitrogen
Retesting
A new test cycle after each defect was repaired
A month under pressure
After restoration, the system was filled with nitrogen and left under high pressure for almost a month. This duration made it possible to detect even minor leaks that might not have shown up during a short test
Each defect found required opening up ceilings, locating the damage, rebrazing and carrying out another pressure test cycle. Installation of the outdoor units began only after all circuits had been confirmed leak-tight
Protecting the new equipment
Even after cleaning, there was still a risk of fine contaminants entering the compressors of the new outdoor units. To protect the equipment, we provided additional refrigerant filtration assemblies that also operated in reverse-flow mode
This reduced the risks during initial start-up and protected the system’s most expensive components
Start-up
Once testing was complete, eight new outdoor units with a total cooling capacity of 400 kW were installed. We then commissioned the system, configured the controls, checked all indoor units and tested operation in different modes
Result
The VRF system was fully commissioned without replacing the installed indoor units or removing the entire refrigerant pipework network. The client retained a substantial part of the previous investment and avoided extensive alterations to the building
The main achievement of this project went beyond simply starting the equipment. We verified the technical suitability of the existing infrastructure, restored its serviceability and safely integrated the old part of the system with new equipment
A complex engineering system does not always need to be removed. The first step is to establish exactly which parts can be safely retained