Bluebox Chiller Controls Upgrade
Job Description: Bluebox Chiller Controls Upgrade
Area: Rex House, London
Issue Identified: Following our recent on-site attendance many control items, such as the PCB (printed circuit board) controllers and main control boards, have become obsolete and non-functional.
Our proposal offered a major cost saving over new equipment and will maximise the efficiency of the existing chillers and will enable ‘open protocol’.
Additional benefits are:
- Effective life cycle extension 2-5 years + (this based on a strict maintenance and treatment plan and subject to new REFCOM alteration plans).
- Reduced energy requirement (circa 5 – 10% + power reduction).
- Refrigeration system and chiller control and mechanical Improvement.
- Minimal building disruption (chiller upgrade was carried out whilst keeping building operational).
Works and Specifications:
- install Carel electronic expansion valve.
- This involved cutting the liquid line pipework and adjusting both the copper pipework and new EEV control wiring.
- Sizing and selection matched the duty range of the TEV.
CONDENSER ASSEMBLIES
- We modulated all condenser fan motors with the inverter pressure controller, which received a 0-10v input from the new chiller controls, based on the desired refrigerant head pressure control. The controller monitor’s the head pressure on both circuits and controls on the higher value. The output from the inverter to each condenser fan motor will pass through a motor starter which will protect the inverter in the event of a motor failure. The greater control of condenser head pressure will increase the efficiency of the chiller and reduce the amount of energy consumption.
CONTROLS UPGRADE
- The existing controls were replaced with new Carel PCO5 units, which represent the most advanced offering available in the field of programmable controllers. The system selected for this application included bespoke strategy, which was created to integrate existing BMS ‘Doorway’ and will offer the most up to date features. These controllers and boards were installed into new customized electrical plates.
- In addition, new sensors and pressure transducers were fitted to each circuit of the chiller and wired back to the control boards in addition to the replacement of all safety devices.
COMMISSIONING
- Following the above works, each circuit was recovered of refrigerant into certified cylinders and pressure tested with oxygen-free dry nitrogen to 10bar. Any leaks identified were repaired.
- Each circuit was then progressively re-pressure tested with all valves open to 10bar. When stable and holding, the high side was isolated from the low side and the pressure in the high side increased to 24bar.
- A minimum 12hr drop test was carried out. Pressures witnessed and signed off by client personnel before and after the test.
- Upon the acceptance of the drop test the nitrogen pressure was vented and the circuits evacuated down to 2torr, with a further 20-minute rise test.
- All data was logged and documented during the commissioning process and a copy of the operational report and Carel PCO5 controller’s configuration was given to the client.
- We also provided onsite training to staff on the PCO5 chiller controller.