Mitsubishi VRF Air Conditioning Repair

We have completed another Mitsubishi VRF repair in Leicester, This system had been confirmed as operating as recently as 4 months prior in heating mode, however when the Hot weather Rolled in it was Cooling which was required. This Medical facility and its patients rely on the system operating correctly to provide comfort heating and cooling. 

Our team of Air Conditioning Engineers Were called in by the facility management team to investigate and remedy the issues with the system, which was not presenting any fault codes to aid in diagnostics. Routine maintenance has been carried out to a high standard so this was not an area of concern. 

Initial Assessment

Upon arrival, we found the Mitsubishi VRF system sitting in an idle state, some controllers were calling for operation in cooling mode, fans were operating and no error codes presented. The centralised controller indicated that most of the rooms inside were calling for cooling mode, apart from 1 room which was calling for heating, as a temporary measure the customer has supplied this room with a mobile Air Conditioning system which was disrupting the signal of the VRF. Once this was disabled the VRF and centralised controller are now calling for 100% cooling mode.

Identifying Technical Issues

Upon inspection of the VRF system we found it attempting to operate in cooling mode, interrogation checks of the Dip switches to the outdoor unit identified multiple areas of abnormality, specifically the temperature of refrigeration leaving temperature from the VRF to the indoor units. Refrigeration pressures were also abnormal and required separate confirmation. The flow direction of refrigerant through the 4 way valve is often easy to confirm when operating correctly, cold in and out of 2 pipes, hot and and out of the other 2, this direction change is the sole operation of the 4 way valve to switch the system into heating mode. In this instance the hot gas was passing through all sections of pipe, with no indication of cold gas. This led to our diagnostic of 4 way valve failure. 

VRF Repair Procedure 

The refrigerant contained within the system has to be recovered and weighed to confirm if the correct quantity is charged. Original installation and commissioning details were available and used to check against the charge of the system. It was found to be lower than the expect charge, in this instance it is necessary to pressure test the entire system and check for areas of refrigerant leak on top of the required replacement 4 Way valve. The 4 way valve is cut in some sections and unbrazed (or sweated off), the pipework is then prepped, cut, cleaned were required. The new valve is placed and protected from heat by a special heat shield putty. During the braze procedure nitrogen must be purged to prevent oxidisation inside the pipework. Once the new valve has been installed and the pressure test has held for a minimum of 24 hours we are satisfied there are no leaks and the system is ready to be re charged with new refrigerant and tested.

Electrical work

During the repair process the power supply is isolated and locked off to prevent accidental power up of a system out of commission. Labels are attached to inform any operatives who and why the isolator is locked off. Following the repair the system is then powered back up and will go into internal checks and provide fault codes if any errors or issues are detected. In this instance the system gave the all clear and testing is ready to begin. 

Testing & Commissioning

Following completion of the 4 way valve replacement and full system recharge VRF, the easiest way to carry out testing was by operating the buildings centralised control, this allows complete operation without individual override, which could impact the test procedure. All areas are calling to operate in cooling modes, we can witness temperature changes in each room and identify any that appear to be sub optimal. With all systems now operating at full capacity the test is concluded and confirmed the repair as a success, we handed control of the Medical facility's systems back to the staff to operate as individual areas require.

Air Source Heat pumps

Heat pump systems come in all shapes and sizes, often these are thought of as replacement for boiler systems by providing hot water to heat radiators etc. Air conditioning systems, whilst primarily considered for cooling, will also provide heating at a cheaper rate than conventional electrical methods, comparable to the cost of a gas boiler. a single room operating a single Heat pump system can be as little as 15 p P/hr to operate. If this approach is then expanded to all rooms of a property the ongoing savings can be tremendous. 

Looking for Commercial Air Conditioning Repairs?

If your air conditioning systems require technical fault identification or service, contact Davenport Cooling Services Limited for professional assistance. Our Engineers are available for 24 hour call out for emergency repairs and service across Leicestershire and the East midlands