Job Description: Liebert Close Control Units Upgrade
Area: 3M Centre, Bracknell
Issue Identified: The framework, evaporators, and condensers on the existing Liebert Close Control Units were in good condition, however many control items, such as the PCB boards (printed circuit boards) and main control boards, had become obsolete or failed due to age and condition.
Our proposal offered a major cost saving over new equipment, it will considerably increase the life of the existing units.
Additional benefits are:
- Refrigeration system & chiller control improvement.
- Minimal building disruption (unit upgrade carried out one at a time).
- Carel updated new style controllers with Carel Key Link. This enables software copies for a future board replacement.
- Accurate time and date alarm log with historical system saving.
- Ease of use interface to reduce specialist call out requirements due to poor alarm log and confusing one button interface.
- Compatibility we remove monitoring Tera, BMS and open protocol interfaces.
Works carried out:
- The refrigerant was recovered into certified storage cylinders for charge confirmation.
- A pressure test was undertaken and witnessed by a representative of the client, before and after the 24-hour test period.
Close control UPGRADE/CONVERSION:
Liebert software:
Due to the nature of the works and obsolete parts the software used within the installation was custom written off site. This is not standard software. The writing of all Carel 1Tool Software was undertaken using existing unit parameters.
CONDENSER ASSEMBLIES:
We modulated all condenser fan motors with existing fan speed controllers, which received a 0-10v input from the new unit controllers, which was based on the desired refrigerant head pressure control.
CONTROLS UPGRADE:
The existing Liebert controls were replaced with new Carel PCO3-5 units, which represent the most advanced offering available in the field of programmable controllers. These controllers and boards were installed into the existing electrical panels.
In addition, new sensors were fitted to each circuit of the chiller and wired back to the control boards.
A new style Carel controller navigator was installed to enable navigation via parameters.
COMMISSIONING:
Upon the acceptance of the drop test, the nitrogen pressure was vented, and the circuits evacuated down to 2 torr, with a further 20-minute rise test.
Each circuit was then charged with existing R407C refrigerant and test ran.
All data was logged and documented during the commissioning process and a copy of the operational report and Carel PCO controller’s configuration was given to the client.
Included:
– The de/recommissioning of refrigerant circuits with virgin refrigerant.
– Pressure testing and evacuation to manufacturers specifications.
– Full system logging and analysis.