Simonswood Automation has recently completed a complete upgrade of the HVAC systems running on the pair of Northlink Ferries running between Aberdeen and Shetland/Orkney in association with co-at marine Ltd of Glasgow. The vessels MV Hrossey and MV Hjaltland, both ten years old, had all their heating, ventilation and air conditioning controlled by obsolete equipment which was becoming harder and harder to maintain and the decision was taken to update all equipment to current technology. The challenge was not only to replace all this equipment without compromising the extensive manual backup systems that were in place, but also to install and commission the equipment during the a very tight 2 week dry dock period – a huge undertaking given that the system is controlled by 9 networked PLCs and overseen by dual SCADA systems operating on the bridge and in the engine room.
To allow easy and direct replacement of the existing controllers, Wago System 750 hardware was chosen. This range of hardware not only benefits from flexible and modular programming software, but also features many specialised input and output cards particularly tailored towards buildings management systems. Not only are all the controllers networked over Modbus TCP to allow full operation even during a SCADA blackout, each has a built in web interface to give maintenance personnel full access to the entire system through a simple Internet Explorer window. The SCADA nodes in the Wheelhouse and Engine Room are both running Wonderware InTouch 2012.
The package controls all extraction and air conditioning fans, together with the cold and hot water heating systems. A number of the extraction systems use variable speed fans which are loop controlled to maintain preset pressures – a very important function to ensure evacuation routes are accessible in the event of a fire. Heating and cooling in all areas of each ship is also accurately monitored and controlled together with humidity control in all public areas. To improve system efficiency, enthalpy wheels (a heat recovery device) are also used to recycle the warm exhaust air to reduce the amount of heating required.
As with many of today’s systems, the system benefits from full remote access capabilities meaning that faults can be diagnosed and upgrades performed even when the vessels are at sea, vastly reducing maintenance budgets and ensuring passenger comfort at all times. The system upgrade was one of a number that have been carried out in association with co-at marine Limited and continues the strong links between the two companies in the Marine Industry.